Relay Catalysis for Selective Aerobic Oxidative Esterification of Primary Alcohols with Methanol
利用继承催化剂实现一氧化氧化醇与甲醇的选择性酯化
- Yibo Yu 于一波Yibo YuResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Yibo Yu
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- Jie Lin 杰琳Jie Lin 杰琳Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. China
复旦大学化学系分子识别与合成研究中心,中国上海 200433 号 220 号邯郸路More by Jie Lin 更多由林杰 - ,
- Anni Qin 安妮秦Anni QinResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Anni Qin
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- Huanan Wang 华南王Huanan WangResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Huanan Wang
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- Jie Wang 杰王Jie WangResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Jie Wang
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- Weiyi Wang 王伟一Weiyi WangResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Weiyi Wang
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- Guolin Wu 吴国林Guolin WuResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Guolin Wu
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- Qian Zhang 前章Qian ZhangResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Qian Zhang
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- Hui Qian* 回钱Hui Qian*E-mail: qian_hui@fudan.edu.cnResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaMore by Hui Qian
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- Shengming Ma* 生命吗*Shengming Ma*E-mail: masm@sioc.ac.cnResearch Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai 200433, P. R. ChinaState Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, P. R. ChinaMore by Shengming Ma
Abstract 摘要

Esters are bulk and fine chemicals and ubiquitous in polymers, bioactive compounds, and natural products. Their traditional synthetic approach is the esterification of carboxylic acids or their activated derivatives with alcohols. Herein, a bimetallic relay catalytic protocol was developed for the aerobic esterification of one alcohol in the presence of a slowly oxidizing alcohol, which has been identified as methanol. A concise synthesis of phlomic acid was executed to demonstrate the practicality and potential of this reaction.
酯是大宗和精细化学品,在聚合物、生物活性化合物和天然产物中无处不在。它们的传统合成方法是羧酸或其活化衍生物与醇的酯化反应。在此,开发了一种双金属继电催化协议,用于在缓慢氧化的醇(已确定为甲醇)存在下进行一种醇的空气酯化反应。执行了富洛酸的简明合成,以展示该反应的实用性和潜力。
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Due to the global concern of natural resources and the environment, (1) more and more attention has been paid to enforce sustainable development of the whole society, thus, there is a great demand of the development of green production technology for the commodity chemicals and functional molecules. (2) Traditional oxidation reactions are an essential reaction for both the academic laboratory and industry, requiring at least stoichiometric amounts of oxidants, causing serious environmental burden. For this reason, catalytic aerobic oxidations, which use oxygen as the oxidant, have been actively pursued. The catalytic aerobic oxidations of primary alcohols, especially catalysis by transition metals such as Pd, (3a,b) Au, (3c,d) Ru, (3e,f) Cu, (3g,h) Fe, (3i,j) etc., affording aldehydes or carboxylic acids have been well developed (Figure 1B). (4) On the other hand, carboxylic acid esters are one of essential chemicals due to their widespread existence in bulk and fine chemicals, polymers, natural products, and drug molecules. (5a) For some typical examples of methyl esters, see Figure 1A. The traditional approach is esterification of carboxylic acids and their derivatives, such as acyl halides, anhydrides, etc., with alcohols (Figure 1C). (5) Dehydrogenative cross-coupling of alcohols to esters at high temperature is also a very useful strategy. (6) The more ideal approach would be the aerobic oxidative esterification of the primary alcohol in the presence of another alcohol, but the accompanying challenges are (1) the selectivity issues referring to diversified oxidation byproducts including aldehydes and carboxylic acids and (2) the selectivity issues forming four esters C1–C4 via both cross-esterification and self-esterification (Figure 1D). (7−10) We proposed a concept of relay catalysis (11) with catalytic recipes A and B (Figure 1E). The catalytic recipe A could recognize the difference of the two primary alcohols, which oxidize one to aldehyde and leave the other one untouched. Then the catalytic recipe B is responsible for the 1,2-addition of the in situ formed aldehyde with the unreacted alcohol to form the semiacetal and its subsequent oxidation to the target ester. Thus, the goal is to identify the suitable relay catalysis and the slowly oxidizing alcohol. Here we report our successful development of such a bimetallic protocol of Fe and Bi for the highly selective aerobic oxidative cross esterification of alcohols with MeOH, which was identified as the very slowly oxidizing primary alcohol, with the help of a catalytic amount of TEMPO (Figure 1F).
由于全球对自然资源和环境的关注,(1)越来越多的关注被付诸于整个社会的可持续发展,因此,对商品化学品和功能分子的绿色生产技术的发展有着巨大需求。 (2)传统的氧化反应对于学术实验室和工业都是必不可少的反应,需要至少化学计量的氧化剂,造成严重的环境负担。因此,利用氧气作为氧化剂的催化空气氧化反应一直受到积极追求。特别是过渡金属如 Pd(3a,b),Au(3c,d),Ru(3e,f),Cu(3g,h),Fe(3i,j)等的催化空气氧化一级醇,得到醛或羧酸已经得到很好的发展(图 1B)。 (4)另一方面,由于羧酸酯在大宗和精细化学品、聚合物、天然产物和药物分子中的广泛存在,它们是必不可少的化学品之一。 (5a)有关甲酯的一些典型示例,请参见图 1A。 传统方法是酯化羧酸及其衍生物,如酰卤、酐等,与醇发生反应(图 1C)。(5) 在高温下醇的脱氢交叉偶联生成酯也是一种非常有用的策略。(6) 更理想的方法是在另一种醇的存在下,通过空气氧化酯化一级醇,但伴随的挑战是(1) 选择性问题,包括醛和羧酸等多样化氧化副产物,以及(2) 选择性问题,形成四种酯 C1-C4,既通过交叉酯化又通过自身酯化(图 1D)。(7-10) 我们提出了一个中继催化的概念(11),使用催化配方 A 和 B(图 1E)。催化配方 A 能够识别两种一级醇的差异,将其中一种氧化为醛,而另一种则不受影响。然后,催化配方 B 负责将原位生成的醛与未反应的醇进行 1,2-加成反应,形成半缩醛,随后氧化为目标酯。 因此,目标是确定适合的中继催化和缓慢氧化的醇。在这里,我们报告了我们成功开发的 Fe 和 Bi 的双金属协同催化协议,用于高选择性的醇与 MeOH 的氧化交叉酯化反应,MeOH 被确定为非常缓慢氧化的初级醇,在 TEMPO 的催化剂量的帮助下(图 1F)。
Figure 1 图 1

Figure 1. Approaches for the synthesis of esters. (A) Selected important methyl esters. (B) The state of the art of aerobic oxidation of primary alcohols. (C) Traditional approaches for the synthesis of esters. (D) The challenges for the esterification of two alcohols. (E) The concept of relay catalysis for selective aerobic esterification. (F) This work: aerobic cross esterification of primary alcohols with methanol.
图 1. 酯合成方法。(A) 选择重要的甲酯。(B) 一级醇的空气氧化的最新技术。(C) 酯合成的传统方法。(D) 两种醇酯化的挑战。(E) 选择性空气酯化的中继催化概念。(F) 本研究:一级醇与甲醇的空气交叉酯化。
Based on our hypothesis, the oxidative esterification of cetyl alcohol 1a with a series of different alcohols was conducted (Table 1). After tedious screening, BiCl3 has been identified as the potential cocatalyst together with Fe(NO3)3·9H2O and TEMPO for such a target transformation. (12) As reported, the reaction of 1a with benzyl alcohol 2a afforded the corresponding aldehydes 3a/8a (7) and the self-esterification product 5a/10a (9,10) (Table 1, entry 1); with n-BuOH, 51% of palmitaldehyde 3a and 32% of butyraldehyde 8b (7h) were obtained with 11% of recovery of 1a. Disappointingly, due to the overlap of signals for esters 6ab, 5a, and 11ba, the specific yield of cross-esterification product 6ab was not able to be determined, and only the combined yield of three esters 6ab, 5a, and 11ba was available (Table 1, entry 2, for detail, see Supporting Information). Interestingly, with n-propanol, we surely observed the formation of the cross-esterification product 6ac (Table 1, entry 3); with ethanol, the yield of the cross-esterification product 6ad was improved to 14% (Table 1, entry 4). Surprisingly, the reaction with methanol afforded 6ae in 83% yield highly selectively (Table 1, entry 5). As a comparison, 49% of alcohol 1a was recovered and 45% of acetone 8f was detected when the sterically more hindered i-propanol was applied instead of methanol (Table 1, entry 6). Thus, methanol was identified as the slowly oxidizing alcohol for the target transformation. (13,14) For more detailed optimizations on the reaction of 1a in the presence of methanol, see the Supporting Information (Table S2–8).
根据我们的假设,已进行了十六醇 1a 与一系列不同醇类的氧化酯化反应(表 1)。经过繁琐的筛选,已确定 BiCl0 作为潜在的辅助催化剂,与 Fe(NO1)2·9H3O 和 TEMPO 一起用于这种目标转化。(12)据报道,1a 与苄醇 2a 的反应产生了相应的醛 3a/8a(7)和自酯化产物 5a/10a(9,10)(表 1,入口 1);与正丁醇反应,得到了 51%的棕榈醛 3a 和 32%的丁醛 8b(7h),回收了 11%的 1a。令人失望的是,由于酯 6ab、5a 和 11ba 的信号重叠,无法确定交叉酯化产物 6ab 的特异产率,只能获得三种酯 6ab、5a 和 11ba 的综合产率(表 1,入口 2,详见支持信息)。有趣的是,用正丙醇,我们确实观察到了交叉酯化产物 6ac 的形成(表 1,入口 3);用乙醇,交叉酯化产物 6ad 的产率提高到 14%(表 1,入口 4)。 出乎意料的是,与甲醇反应高度选择性地得到了 6ae,收率为 83%(表 1,第 5 项)。作为对比,当使用受空间位阻影响更大的异丙醇代替甲醇时,醇 1a 的 49%被回收,检测到了乙酮 8f 的 45%(表 1,第 6 项)。因此,甲醇被确定为目标转化中氧化速度较慢的醇。(13,14)有关在甲醇存在下对 1a 反应的更详细优化,请参阅支持信息(表 S2–8)。
表 1. 缓慢氧化醇的鉴定 a


The reaction was conducted with 1a (1.0 mmol), R′CH2OH (5.0 mmol), Fe(NO3)3·9H2O (6 mol %), nitroxyl (5 mol %), and Lewis acid (10 mol %) in 3 mL of solvent at T °C for 48 h with an O2 balloon. The NMR yield and recovery were determined by 1H NMR analysis using dibromomethane as the internal standard.
a 反应在 1a(1.0 mmol)、R′CH 2 OH(5.0 mmol)、Fe(NO 3 ) 3 ·9H 2 O(6 mol %)、亚硝基(5 mol %)和 Lewis 酸(10 mol %)在 3 mL 溶剂中,在 T °C 下进行 48 小时,使用 O 2 气球。NMR 收率和回收率通过使用二溴甲烷作为内部标准进行 1 H NMR 分析来确定。
Combined yield of 6ab, 5a, and 11ba based on alcohol 1a.
基于酒精 1a,6ab、5a 和 11ba 的综合产量。
Combined yield of 5a and 11ca based on alcohol 1a.
基于酒精 1a 的 5a 和 11ca 的综合产量。
ND = not determined.
d ND = 未确定。
With the optimized reaction conditions in hand, we explored the generality of this method for the aerobic synthesis of methyl carboxylates from different primary alcohols (Scheme 1). Nonfunctionalized aliphatic alcohols and 3-cyclohexylpropanol performed well, with methyl esters 6ae–6de being isolated in 73–75% yields. Aliphatic alcohols with different carbon chains containing phenyl also worked, providing 6ee–6he in up to 79% yields. Additionally, 3-arylpropanols incorporating either electron-withdrawing or electron-donating groups, such as cyano, nitro, trifluoromethyl, chloro, and methoxy, were all smoothly oxidized to corresponding products 6ie–6me in moderate yields with these functional groups untouched. It was worth noting that the yield of 6ie was increased from 48% to 54% with a slightly lower concentration. In addition, a variety of functional groups in alkyl alcohols, such as various ethers, highly reactive functionalities toward methanol, including bromo, iodo, MsO, TsO, amides, and even diverse esters, were well tolerated, affording 6ne–6ze in moderate to good yields.
有了优化的反应条件,我们探索了这种方法在不同一级醇(方案 1)中用于空气合成甲基羧酸酯的普适性。非官能化的脂肪族醇和 3-环己基丙醇表现良好,得到的甲酯 6ae-6de 的收率为 73-75%。含有苯基的不同碳链的脂肪族醇也有效,提供 6ee-6he,收率高达 79%。此外,含有电子吸引或电子供给基团的 3-芳基丙醇,如氰基、硝基、三氟甲基、氯和甲氧基,都顺利氧化为相应产物 6ie-6me,收率适中,这些官能团保持不变。值得注意的是,通过略低的浓度,6ie 的产率从 48%增加到 54%。此外,烷基醇中的各种官能团,如各种醚、对甲醇高度反应的官能团,包括溴、碘、MsO、TsO、酰胺,甚至多样的酯,都能很好地耐受,产率适中至良好,得到 6ne-6ze。
Scheme 1 方案 1

方案 1. 基底范围 a
aThe reaction was conducted with 1 (1.0 mmol), MeOH (5.0 mmol), Fe(NO3)3·9H2O (6 mol %), TEMPO (5 mol %), and BiCl3 (10 mol %) in 3 mL of DCE at 50 °C for 48 h with an O2 balloon.
反应在 50°C 下进行,使用 1(1.0 毫摩尔)、MeOH(5.0 毫摩尔)、Fe(NO3)3·9H2O(6 摩尔%)、TEMPO(5 摩尔%)和 BiCl3(10 摩尔%)在 3 毫升 DCE 中进行,使用 O2 气球反应 48 小时。
b4 mL of DCE were used.
使用了 4 毫升 DCE。
cThe reaction time was 60 h, 47% isolated yield.
反应时间为 60 小时,分离收率为 47%。
dNMR yield under standard conditions.
d 标准条件下的 NMR 收率。
e8 mol % each of Fe(NO3)3·9H2O and TEMPO were used.
使用了 Fe(NO3)3·9H2O 和 TEMPO 各 8 摩尔%。
f4 mmol of MeOH were used.
使用了 4 毫摩尔的甲醇。
g8 mol % of Fe(NO3)3·9H2O was used.
使用了 8 摩尔%的 Fe(NO3)3·9H2O。
h5 mmol scale reaction.
5 毫摩尔比例的反应。
i10 mol % of TEMPO was used.
使用了 10 摩尔%的 TEMPO。
jNMR yield of the aldehydes in parentheses determined by 1H NMR analysis using dibromomethane as the internal standard.
用二溴甲烷作为内标准,通过 1 H NMR 分析确定括号中醛的 NMR 收率。
kNMR yield of the acetal determined by 1H NMR analysis using dibromomethane as the internal standard.
使用二溴甲烷作为内标,通过 1 H NMR 分析确定缩醛的 k NMR 收率。
The C═C bond was readily accommodated, providing 6Ae and 6Be smoothly. In addition, both terminal and internal C–C triple bonds were compatible, providing the corresponding methyl esters 6Ce–6He in satisfactory yields. The corresponding aldehyde and acetal were also formed in 17% NMR yield, respectively, under standard conditions, accounting for the lower yield for 6Ge. Notably, methyl oct-2-ynoate 6He, which is commonly used as flavoring agents to prepare cucumber, banana, strawberry, peach, etc., was obtained easily from the corresponding alcohol 1H under the standard conditions in 64% yield. The reactions of branched alcohols 1I and 1J with methanol were much slower, affording the methyl esters 6Ie and 6Je in 44% and 33% yield, respectively, together with the related aldehydes 3I and 3J, which could be attributed to the increased steric hindrance. By applying the present protocol following enantioselective allenation of alkynes reaction (EATA), (12d,15) a three-step concise synthesis of phlomic acid isolated from Phlomis in 1997 (16) has been realized successfully. First, a 5 mmol scale reaction afforded methyl hept-6-ynoate 6Ce in 65% isolated yield, which underwent EATA reaction with dodecaldehyde 3c in the presence of (S)-dimethylprolinol (S)-12. Pholmic acid (Ra)-13 was obtained by hydrolysis in the presence of KOH in 59% total yield with 97% ee.
C═C 键容易适应,顺利提供 6Ae 和 6Be。此外,末端和内部的 C–C 三键也是兼容的,提供了相应的甲酸甲酯 6Ce–6He,收率令人满意。相应的醛和缩醛在标准条件下分别以 17%的 NMR 收率形成,解释了 6Ge 的较低收率。值得注意的是,常用作调味剂以制备黄瓜、香蕉、草莓、桃子等的甲基辛-2-炔酸甲酯 6He,可在标准条件下从相应的醇 1H 中轻松获得,收率为 64%。支链醇 1I 和 1J 与甲醇的反应速度要慢得多,分别以 44%和 33%的收率提供了甲酸甲酯 6Ie 和 6Je,以及相关的醛 3I 和 3J,这可能归因于增加的立体位阻。通过应用当前的协议,遵循烯丙基选择性炔烃反应(EATA),成功实现了从 1997 年 Phlomis 中分离的 phlomic 酸的三步简洁合成。 首先,5 mmol 的反应产生了甲酸庚-6-炔酸甲酯 6Ce,收率为 65%,随后在(S)-二甲基丙氨醇(S)-12 存在下,与十二醛 3c 发生了 EATA 反应。在 KOH 存在下水解后,得到了酚酸(R a )-13,总产率为 59%,ee 值为 97%。
In conclusion, we have successfully developed a BiCl3 and iron nitrate cocatalyzed selective oxidative esterification of primary alcohols in the presence of methanol with molecular oxygen as an environmentally benign oxidant with the help of TEMPO. A wide range of alcohols bearing various highly reactive functional groups, such as halogens, ethers, esters, amide, C═C, C≡C, etc., may be converted to the corresponding methyl esters in moderate to high yields. A highly concise three-step enantioselective synthesis of phlomic acid has been achieved by using the current protocol as the key step. Further studies are being actively pursued in our laboratory.
总之,我们成功地开发了一种 BiCl 3 和硝酸铁共催化的选择性氧化酯化初级醇的方法,在甲醇存在下,以分子氧作为环境友好的氧化剂,在 TEMPO 的帮助下。各种含有各种高度反应性官能团的醇,如卤素、醚、酯、酰胺、C═C、C≡C 等,可以在中等到高收率下转化为相应的甲酯。通过使用当前方案作为关键步骤,已经实现了对 phlomic 酸的高度简洁的三步对映选择性合成。我们实验室正在积极进行进一步的研究。
Data Availability 数据可用性
The data underlying this study are available in the published article and its Supporting Information
该研究的数据可在已发表的文章及其支持信息中获得
Supporting Information 支持信息
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.orglett.4c01059.
支持信息可免费获取,网址为 https://pubs.acs.org/doi/10.1021/acs.orglett.4c01059。
Optimizations, experimental procedures, and NMR spectra for obtained compounds (PDF)
获得化合物的优化、实验程序和 NMR 光谱(PDF)
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Acknowledgments
Financial support from National Key R&D Program of China (Grant No. 2022YFA1503200) and National Natural Science Foundation of China (Grant No. 21988101) are greatly appreciated.
This article references 16 other publications.
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For selected seminal reports on aerobic oxidation of alcohols via transition-metal catalysis, see the following articles. With Pd catalysts:
(a) Blackburn, T. F.; Schwartz, J. Homogeneous catalytic oxidation of secondary alcohols to ketones by molecular oxygen under mild conditions. J. Chem. Soc., Chem. Commun. 1977, 157, DOI: 10.1039/c39770000157Google ScholarThere is no corresponding record for this reference.(b) Fiege, H.; Wedemeyer, K. Activation of Oxidations with Oxygen on Platinum Metals Using the Example of the Conversion of 2-Phenoxyethanols to Phenoxyacetic Acids. Angew. Chem., Int. Ed. Engl. 1981, 20, 783, DOI: 10.1002/anie.198107831Google ScholarThere is no corresponding record for this reference.With Au catalysts:
(c) Milone, C.; Ingoglia, R.; Neri, G.; Pistone, A.; Galvagno, S. Gold catalysts for the liquid phase oxidation of o-hydroxybenzyl alcohol. Appl. Catal., A 2001, 211, 251, DOI: 10.1016/S0926-860X(00)00875-9Google Scholar3chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXisVWisLc%253D&md5=36d39c244b309ddc162e3155d7b39260Gold catalysts for the liquid phase oxidation of o-hydroxybenzyl alcoholMilone, C.; Ingoglia, R.; Neri, G.; Pistone, A.; Galvagno, S.Applied Catalysis, A: General (2001), 211 (2), 251-257CODEN: ACAGE4; ISSN:0926-860X. (Elsevier Science B.V.)Gold on iron oxide catalysts have been investigated in the liq. phase oxidn. of o-hydroxybenzyl alc. (salicylic alc.) under mild conditions. The presence of gold strongly enhances the catalytic activity of iron oxide, which is practically inactive under the same reaction conditions. The liq. phase oxidn. of salicylic alc. follows a first order reaction rate law with respect to the org. substrate. The order of reaction with respect to the oxygen partial pressure is close to zero. The catalytic activity increases with the gold loading. The oxidn. of salicylic alc. on the catalysts with low gold loading leads to the formation of salicylic aldehyde as the main reaction product. A small amt. of salicylic acid was also obtained. On the catalysts with higher gold loading a progressive decrease of the yield to salicylic aldehyde with the conversion level occurs. When the reaction is carried out using benzene as solvent, the salicylic aldehyde is the end products on all the catalysts investigated regardless of the gold content.(d) Prati, L.; Rossi, M. Gold on carbon as a new catalyst for selective liquid phase oxidation of diols. J. Catal. 1998, 176, 552, DOI: 10.1006/jcat.1998.2078Google Scholar3dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXjvFemsr0%253D&md5=f4f0bd7c492a3e299039327b621a7a84Gold on carbon as a new catalyst for selective liquid phase oxidation of diolsPrati, Laura; Rossi, MicheleJournal of Catalysis (1998), 176 (2), 552-560CODEN: JCTLA5; ISSN:0021-9517. (Academic Press)Catalytic oxidn. of vicinal diols to α-hydroxy carboxylates with O in alk. soln. was performed by using Au-based catalysts. The influence of support and prepn. method on both activity and selectivity was studied. Under mild conditions, high selectivities were achieved toward monooxygenation of ethylene glycol and propylene glycol with high diol conversion. The racemization of optically active propylene glycol during its oxidn. as well as isotopic H-D exchange expts. allowed us to deduce features of the mechanism. The recycling of Au/C catalyst revealed its good resistance toward deactivation.With Ru catalysts:
(e) Matsumoto, M.; Ito, S. Ruthenium-catalysed oxidation of allyl alcohols by molecular oxygen. J. Chem. Soc., Chem. Commun. 1981, 907, DOI: 10.1039/c39810000907Google ScholarThere is no corresponding record for this reference.(f) Murahashi, S.; Naota, T.; Hirai, N. Aerobic oxidation of alcohols with ruthenium-cobalt bimetallic catalyst in the presence of aldehydes. J. Org. Chem. 1993, 58, 7318, DOI: 10.1021/jo00078a002Google Scholar3fhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXhs1aqs7Y%253D&md5=ff17b7a32d9093577132e9c5e74bf3feAerobic oxidation of alcohols with ruthenium-cobalt bimetallic catalyst in the presence of aldehydesMurahashi, Shunichi; Naota, Takeshi; Hirai, NaruhisaJournal of Organic Chemistry (1993), 58 (26), 7318-19CODEN: JOCEAH; ISSN:0022-3263.Aerobic oxidn. of alcs. proceeds highly efficiently at room temp. Thus, various aliph. and arom. alcs. can be oxidized with mol. O in the presence of a 1:1 mixt. of RuCl3 and Co(OAc)2 catalyst and an aldehyde at room temp. under O2 atmosphere (1 atm) to give the corresponding ketones. Similar treatment of primary alcs. gives the corresponding carboxylic acids. This reaction is highly convenient because of its simple operation, mild reaction conditions, and high efficiency. The reaction can be rationalized by assuming 2 sequential pathways; first, formation of peracids by cobalt-mediated radical chain reaction of aldehydes with mol. O, second, Ru-catalyzed oxidn. of alcs. with the peracids thus formed.With Cu catalysts:
(g) Semmelhack, M. F.; Schmid, C. R.; Cortes, D. A.; Chou, C. S. Oxidation of alcohols to aldehydes with oxygen and cupric ion, mediated by nitrosonium ion. J. Am. Chem. Soc. 1984, 106, 3374, DOI: 10.1021/ja00323a064Google Scholar3ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2cXitVylsbc%253D&md5=5d64f572e776e56a17fe1d8022df097aOxidation of alcohols to aldehydes with oxygen and cupric ion, mediated by nitrosonium ionSemmelhack, M. F.; Schmid, Christopher R.; Cortes, David A.; Chou, Chuen S.Journal of the American Chemical Society (1984), 106 (11), 3374-6CODEN: JACSAT; ISSN:0002-7863.Reaction of CuCl2 with the readily available free radical 2,2,6,6-tetramethylpiperidin-1-oxy (TEMPO) produces cuprous ion and the corresponding nitrosonium ion. In this redox system, using CaH2 to scavenge acid as it forms, primary satd., allylic, and benzylic alcs. are converted to aldehydes in high yield at 25°. For the more reactive substrates, allylic and benzylic alcs., the oxidn. can be operated in an efficient catalytic cycle, using O as the oxidizing agent with CuCl and TEMPO present in 2-10 mol %. In this case, no net formation of acid occurs and no base is needed. Representative allylic and benzylic alcs. give the aldehydes in 85-97% yield. Strong preference for primary over secondary allylic alcs. is demonstrated by the lack of reactivity of 2-cyclohexenol and by selective oxidn. of 1,8-nonanediol to 8-hydroxynonanal.(h) Yu, Y.; Zhai, D.; Zhou, Z.; Jiang, S.; Qian, H.; Ma, S. Copper-catalyzed aerobic oxidation of primary alcohols to carboxylic acids. Chem. Commun. 2023, 59, 5281, DOI: 10.1039/D3CC00963GGoogle ScholarThere is no corresponding record for this reference.With Fe catalysts:
(i) Martín, S. E.; Suárez, D. o. F. Catalytic aerobic oxidation of alcohols by Fe(NO3)3–FeBr3. Tetrahedron Lett. 2002, 43, 4475, DOI: 10.1016/S0040-4039(02)00829-8Google ScholarThere is no corresponding record for this reference.(j) Naik, R.; Joshi, P.; Deshpande, R. K. Polymer encapsulation of metallophthalocyanines: efficient catalysts for aerobic oxidation of alcohols. Catal. Commun. 2004, 5, 195, DOI: 10.1016/j.catcom.2004.02.002Google Scholar3jhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhvV2jt7c%253D&md5=79c4c4b54ecdde65d758322f2a0bd673Polymer encapsulation of metallophthalocyanines: efficient catalysts for aerobic oxidation of alcoholsNaik, Rajan; Joshi, Padmakar; Deshpande, Rajesh K.Catalysis Communications (2004), 5 (4), 195-198CODEN: CCAOAC; ISSN:1566-7367. (Elsevier Science B.V.)Metallophthalocynines (MPcs) of iron, cobalt and copper have been successfully encapsulated for the first time on polystyrene matrix, rendering them highly dispersible in common org. solvents. These catalysts were characterized by diffuse reflectance UV-Vis spectra as well as FT-IR spectroscopy. The encapsulated metallophthalocyanines (MCMPcs) were found to be stable and more active than their unencapsulated counterparts. These encapsulated catalysts showed enhanced activity for aerobic oxidn. of alcs. mimicking cytochrome P 450 dependent mono oxygenases. These catalysts not only have high turnover frequencies but could be recovered quant. by simple filtration and reused without loss of activity. Phenethyl alc., benzoin, mandelic acid, and benzyl alc. were oxidized by O in the presence of polystyrene-microencapsulated metallophthalocynines of iron, cobalt, or copper, and KOH in toluene at reflux to acetophenone, benzil, benzoylformic acid, and benzoic acid, resp., in 90-96% yields. - 4
For selected books on oxidation of alcohols, see:
(a) Tojo, G.; Fernández, M. Oxidation of alcohols to aldehydes and ketones: A guide to current common practice; Springer: New York, 2006.Google ScholarThere is no corresponding record for this reference.(b) Tojo, G.; Fernández, M. Oxidation of primary alcohols to carboxylic acids: A guide to current common practice; Springer: New York, 2007.Google ScholarThere is no corresponding record for this reference.For selected recent reviews on aerobic oxidation of alcohols, see:
(c) Parmeggiani, C.; Matassini, C.; Cardona, F. A step forward towards sustainable aerobic alcohol oxidation: new and revised catalysts based on transition metals on solid supports. Green Chem. 2017, 19, 2030, DOI: 10.1039/C7GC00406KGoogle Scholar4chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXkvF2ku7o%253D&md5=49810f57b564f65650ac9364ad86fad6A step forward towards sustainable aerobic alcohol oxidation: new and revised catalysts based on transition metals on solid supportsParmeggiani, C.; Matassini, Camilla; Cardona, F.Green Chemistry (2017), 19 (9), 2030-2050CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. T. He oxidn. of alcs. is a reaction under continuous investigation, due to the importance of oxidn. products and the necessity to perform it in a more sustainable way with respect to traditional procedures. In particular, the combination of a metal catalyst with mol. oxygen or air represents one of the best alternatives in this field. New catalysts are continuously proposed in the literature, and it is not often easy to compare their performances owing to the great amt. of examples reported. Heterogeneous catalysts represent the best soln. to heavy metal contamination of the products, provided that leaching has not occurred. Moreover, they ideally should be recovered without deactivation and reused after reaction. The employment of air or oxygen in non-flammable solvents (ideally, water) is also highly appreciated, for safety reasons. We have tried in this review to focus on some very recent reports on solid supported transition metal catalysts that strive to follow these principles thus performing oxidn. in a more sustainable way while guaranteeing an acceptable substrate scope for synthetic utility.(d) Hazra, S.; Malik, E.; Nair, A.; Tiwari, V.; Dolui, P.; Elias, A. J. Catalytic Oxidation of Alcohols and Amines to Value-Added Chemicals using Water as the Solvent. Chem.─Asian J. 2020, 15, 1916, DOI: 10.1002/asia.202000299Google ScholarThere is no corresponding record for this reference.(e) An, G.; Zhang, X.; Zhang, C.; Gao, H.; Liu, S.; Qin, G.; Qi, H.; Kasemchainan, J.; Zhang, J.; Wang, G. Metal-organic-framework-based materials as green catalysts for alcohol oxidation. Chin. J. Catal. 2023, 50, 126, DOI: 10.1016/S1872-2067(23)64451-1Google Scholar4ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXhs1ynsb3F&md5=b1996f0df41a2f3edd6ce3baf34533ddMetal-organic-framework-based materials as green catalysts for alcohol oxidationAn, Guoqing; Zhang, Xiaowei; Zhang, Canyang; Gao, Hongyi; Liu, Siqi; Qin, Geng; Qi, Hui; Kasemchainan, Jitti; Zhang, Jianwei; Wang, GeChinese Journal of Catalysis (2023), 50 (), 126-174CODEN: CJCHCI; ISSN:1872-2067. (Elsevier B.V.)A review. The selective oxidn. of alcs. is widely regarded as one of the most important reactions in org. synthesis. Although efficient and environmentally friendly catalysts for alc. oxidn. are highly desirable, their development remains an enormous challenge. Metal-org. framework (MOF)-based catalysts have demonstrated great potential in the catalytic oxidn. of alcs. and have remarkably progressed in the past few decades owing to their advantages of large surface area, tunable porous structure, abundant accessible active sites, and ease of reuse and recycling. In this review, recent representative results of the catalytic oxidn. of alcs. by MOF-based materials are summarized and classified according to the type of material and reaction, such as pristine MOFs, MOF composites, and MOF derivs. for traditional thermal catalysis, photo-assisted catalysis, and electro-assisted catalysis. Each catalytic system is described in detail from multiple aspects, including the materials synthesis process, catalytic performance, alc. oxidn. mechanisms, and material stability. Thus, the aims of this review are to identify potentially efficient, green, and reusable MOF-based catalytic systems and to provide new insights for the further development of catalytic alc. oxidn. to obtain the target orgs. - 5(a) Otera, J.; Nishikido, J. Esterification: Method, Reactions, and Applications; Wiley-VCH: Weinheim, 2010.Google ScholarThere is no corresponding record for this reference.(b) Carey, F. A.; Sundbery, R. G. Advanced Organic Chemistry, Part B: Reactions and Synthsis, 5th ed.; Springer: New York, 2007.Google ScholarThere is no corresponding record for this reference.(c) Ekoue-Kovi, K.; Wolf, C. One-Pot Oxidative Esterification and Amidation of Aldehydes. Chem.─Eur. J. 2008, 14, 6302, DOI: 10.1002/chem.200800353Google Scholar5chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXps1Cjtr0%253D&md5=d7b22e7a57ae650b6afe0f740531acd1One-pot oxidative esterification and amidation of aldehydesEkoue-Kovi, Kekeli; Wolf, ChristianChemistry - A European Journal (2008), 14 (21), 6302-6315CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. During recent years, the direct transformation of aldehydes into esters or amides developed into a vigorous research area and powerful one-pot oxidative esterification and amidation procedures were reported. Several concepts that are often complementary in substrate scope, functional group tolerance, and reaction outcome have emerged, thus providing a wide range of alternatives to classical ester and amide synthesis via carboxylic acid intermediates.(d) Tang, S.; Yuan, J.; Liu, C.; Lei, A. Direct oxidative esterification of alcohols. Dalton Trans. 2014, 43, 13460, DOI: 10.1039/C4DT01133CGoogle Scholar5dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1WjsrbJ&md5=7d815ab54a52d282ce1d52d9f15e7087Direct oxidative esterification of alcoholsTang, Shan; Yuan, Jiwen; Liu, Chao; Lei, AiwenDalton Transactions (2014), 43 (36), 13460-13470CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)A review. Esterification is a fundamental transformation in chem. Traditional esterification only largely occurs between carboxylic acid derivs. and alcs., and often involves multistep processes. Developments in the transition-metal-catalyzed and metal-free direct esterification of alcs. under oxidative conditions has opened a door to the efficient, sustainable and environmentally friendly synthesis of esters from readily available materials. This Perspective gives an overview which covers the recent development of this emerging field.
- 6
For a seminal report on dehydrogenative esterification of primary alcohols, see:
Zhang, J.; Leitus, G.; Ben-David, Y.; Milstein, D. Facile Conversion of Alcohols into Esters and Dihydrogen Catalyzed by New Ruthenium Complexes. J. Am. Chem. Soc. 2005, 127, 10840, DOI: 10.1021/ja052862bGoogle Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmt1ansLk%253D&md5=364eb680398a2c200d0d2e15eb245a53Facile Conversion of Alcohols into Esters and Dihydrogen Catalyzed by New Ruthenium ComplexesZhang, Jing; Leitus, Gregory; Ben-David, Yehoshoa; Milstein, DavidJournal of the American Chemical Society (2005), 127 (31), 10840-10841CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)An efficient, environmentally benign method for the prepn. of esters from alcs. under mild, neutral conditions without the need for carboxylic acid derivs. and condensing agents was developed. Catalyst design, based on new Ru(II) hydrido carbonyl complexes incorporating electron-rich bis(phosphinomethyl)pyridine (PNP) and aminomethylphosphinomethylpyridine (PNN) ligands resulted in Ru(PNP/PNN)(CO)Cl(H) and Ru(PNN)(CO)H the latter of which (PNN = diethylaminomethylbis(tert-butyl)phosphinomethylpyridine) is an outstanding catalyst for the dehydrogenation of primary alcs. to esters and H2 under neutral conditions. - 7(a) Hao, Y.; Chong, Y.; Li, S.; Yang, H. Controlled Synthesis of Au Nanoparticles in the Nanocages of SBA-16: Improved Activity and Enhanced Recyclability for the Oxidative Esterification of Alcohols. J. Phys. Chem. C 2012, 116, 6512, DOI: 10.1021/jp2093252Google Scholar7ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XosFChsw%253D%253D&md5=96b68984de2c190ee9f69fa8882aa6baControlled Synthesis of Au Nanoparticles in the Nanocages of SBA-16: Improved Activity and Enhanced Recyclability for the Oxidative Esterification of AlcoholsHao, Yajuan; Chong, Yanzhu; Li, Shuru; Yang, HengquanJournal of Physical Chemistry C (2012), 116 (11), 6512-6519CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Au nanoparticles with different sizes were introduced into the nanocages of a mesoporous material SBA-16 with the aid of chem. modification, leading to new Au-supported catalysts Au/SBA-16. These catalysts were characterized with Fourier transform IR spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microspectroscopy (TEM), N2 sorption, and X-ray photoelectron microspectroscopy (XPS). These results revealed that uniform Au nanoparticles with sizes of a few nanometers were successfully positioned inside the nanocages of SBA-16. Such catalysts were catalytically active in the oxidative esterification of various alcs. even including less reactive straight-chain alcs. It was found that the activity of this catalyst strongly depended on the Au loading, and the Au loading of 5 wt % (corresponding to Au particles of 2-3 nm in sizes) led to the highest activity. Its activity was much higher than those of the analogous catalysts prepd. from com. silica gel as well as SBA-15. Furthermore, Au/SBA-16 could be reused at least eight reaction cycles without significant decrease in activity and selectivity. Its recyclability was much superior to that of the catalyst derived from com. silica gel. The underlying reason may be that the unique nanostructure of SBA-16 can effectively prevent the growth of Au nanoparticles into less active, larger particles, as evidenced from TEM investigations. This study not only supplies a new, active, recoverable catalyst for the green transformations of alcs. to esters but also demonstrates that the three-dimensional mesoporous cage-like material SBA-16 has a superior ability in reducing the diffusion resistance and stabilizing metal nanoparticles against growth.(b) Parreira, L. A.; Bogdanchikova, N.; Pestryakov, A.; Zepeda, T. A.; Tuzovskaya, I.; Farías, M. H.; Gusevskaya, E. V. Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcohol. Appl. Catal., A 2011, 397, 145, DOI: 10.1016/j.apcata.2011.02.028Google Scholar7bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkvVSrsLk%253D&md5=d66940b52cbb1b3d7d1290ed81ade9c6Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcoholParreira, Luciana A.; Bogdanchikova, Nina; Pestryakov, Alexey; Zepeda, T. A.; Tuzovskaya, Inga; Farias, M. H.; Gusevskaya, Elena V.Applied Catalysis, A: General (2011), 397 (1-2), 145-152CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)The materials contg. gold nanoparticles supported on pure and Ce, Ti, or Fe-modified hexagonal mesoporous silica were prepd. and their structural and electronic properties were studied by x-ray diffraction, TEM, XPS, and N2 adsorption techniques. The materials were shown to be effective heterogeneous catalysts for the liq.-phase aerobic oxidn. of benzyl alc. in methanol solns. It was found that the modifiers significantly improve the catalytic properties of supported gold particles and allow performing the selective one-pot oxidative esterification of benzyl alc. resulting in Me benzoate. The modified catalysts exhibited high activity (turnover frequencies of up to ∼1000 h-1), selectivity to Me benzoate (up to 95%), and stability (turnover nos. of up to ∼4300). Ce and Ti were found to be more effective promoters as compared with Fe in terms of catalyst stability.(c) Liu, P.; Li, C.; Hensen, E. J. M. Efficient Tandem Synthesis of Methyl Esters and Imines by Using Versatile Hydrotalcite-Supported Gold Nanoparticles. Chem.─Eur. J. 2012, 18, 12122, DOI: 10.1002/chem.201202077Google Scholar7chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtF2nsbrM&md5=3b4944151d526c4b1c35d25768c343c2Efficient tandem synthesis of methyl esters and imines by using versatile hydrotalcite-supported gold nanoparticlesLiu, Peng; Li, Can; Hensen, Emiel J. M.Chemistry - A European Journal (2012), 18 (38), 12122-12129, S12122/1-S12122/8CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Efficient basic hydrotalcite (HT)-supported gold nanoparticle (AuNP) catalysts were developed for the aerobic oxidative tandem synthesis of Me esters and imines from primary alcs. catalyzed under mild and sol.-base-free conditions. The catalytic performance can be fine-tuned for these cascade reactions by simple adjustment of the Mg/Al at. ratio of the HT support. The one-pot synthesis of Me esters benefits from high basicity (Mg/Al=5), whereas moderate basicity greatly improves imine selectivity (Mg/Al=2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies showed a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidn. of the starting alc. but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the compn. of the support has been shown to yield optimum AuNP catalysts for different tandem reactions. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.(d) Buonerba, A.; Noschese, A.; Grassi, A. Highly Efficient Direct Aerobic Oxidative Esterification of Cinnamyl Alcohol with Alkyl Alcohols Catalysed by Gold Nanoparticles Incarcerated in a Nanoporous Polymer Matrix: A Tool for Investigating the Role of the Polymer Host. Chem.─Eur. J. 2014, 20, 5478, DOI: 10.1002/chem.201303880Google ScholarThere is no corresponding record for this reference.(e) Wei, H.; Li, J.; Yu, J.; Zheng, J.; Su, H.; Wang, X. Gold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditions. Inorg. Chim. Acta 2015, 427, 33, DOI: 10.1016/j.ica.2014.11.024Google Scholar7ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1SmtA%253D%253D&md5=97d3df8ecca06b36d976e2fcfc660caeGold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditionsWei, Huili; Li, Jingyi; Yu, Jing; Zheng, Jianwei; Su, Haiquan; Wang, XiaojingInorganica Chimica Acta (2015), 427 (), 33-40CODEN: ICHAA3; ISSN:0020-1693. (Elsevier B.V.)Gold nanoparticles supported on metal oxides were used to catalyze the direct oxidative esterification of alcs.; esters were obtained using mol. oxygen as an oxidant under ambient temp. and pressure. Higher activities for the reaction between the benzyl alc. and methanol were obtained over Au/CeO2 and Au/ZrO2 than Au/TiO2 (anatase), Au/HT (hydrotalcite) and Au/Al2O3. These catalysts were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), at. absorption spectroscopy (AAS) and XPS. The distribution of gold nanoparticles was uniform; no change of chem. states occurred for supports and gold nanoparticles after the catalysts were reused 10 times. The oxidative esterification of various alcs. over these catalysts could also occur under optimized reaction conditions. The substituted benzyl alcs. and cinnamyl alcs. were more active than heterocyclic alcs. and aliph. alcs. because their α-H could be eliminated more easily during the induction of adsorbed dioxygen. Self-oxidative esterification was available for benzyl alc. in inert solvents with low polarity indexes. A reaction mechanism was proposed for the synthesis of esters from alcs. with mol. oxygen.(f) Verma, S.; Verma, D.; Sinha, A. K.; Jain, S. L. Palladium complex immobilized on graphene oxide–magnetic nanoparticle composites for ester synthesis by aerobic oxidative esterification of alcohols. Appl. Catal., A 2015, 489, 17, DOI: 10.1016/j.apcata.2014.10.004Google ScholarThere is no corresponding record for this reference.(g) Wang, L.; Li, J.; Dai, W.; Lv, Y.; Zhang, Y.; Gao, S. Facile and efficient gold-catalyzed aerobic oxidative esterification of activated alcohols. Green Chem. 2014, 16, 2164, DOI: 10.1039/c3gc42075bGoogle Scholar7ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXks1yrtb8%253D&md5=cfec2837e04921b91de106a1f37bc18dFacile and efficient gold-catalyzed aerobic oxidative esterification of activated alcoholsWang, Lianyue; Li, Jun; Dai, Wen; Lv, Ying; Zhang, Yi; Gao, ShuangGreen Chemistry (2014), 16 (4), 2164-2173CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A facile and efficient methodol. is presented for the direct oxidative esterification of alcs. with alcs. catalyzed by NaAuCl4. Just in the presence of a low catalytic amt. of base additive, the newly developed catalytic system proceeds with high selectivity and broad substrate scope under mild conditions with dioxygen or air as the environmentally benign terminal oxidant. Various alcs. including benzylic and allylic alcs. were smoothly reacted with methanol and even with long-chain aliph. alcs., affording the desired products in good to excellent yields (up to 95% yield). The present system showed high catalytic activity with a TOF up to 219 h-1. Kinetic studies of the reaction process provide fundamental insights into the catalytic pathway, and a possible reaction pathway is proposed based on the results of the control expts. XPS, TEM, and UV-visible were carried out to characterize the chem. state of the Au catalyst in the present catalytic system. The Au nanoparticles were generated in situ and supported on K2CO3, forming a simple, recyclable and selective catalyst system for the direct oxidative esterification of alcs.(h) Liu, C.; Wang, J.; Meng, L.; Deng, Y.; Li, Y.; Lei, A. Palladium-Catalyzed Aerobic Oxidative Direct Esterification of Alcohols. Angew. Chem., Int. Ed. 2011, 50, 5144, DOI: 10.1002/anie.201008073Google Scholar7hhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtFymurk%253D&md5=f300bdd1946d99125ae8f148d59285cbPalladium-catalyzed aerobic oxidative direct esterification of alcoholsLiu, Chao; Wang, Jing; Meng, Lingkui; Deng, Yi; Li, Yao; Lei, AiwenAngewandte Chemie, International Edition (2011), 50 (22), 5144-5148CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)The first palladium-catalyzed direct aerobic oxidative esterification of benzylic alcs. with methanol and various long-chain aliph. alcs. have successfully developed. By considering the effect of substitution and potential mechanistic pathways, the authors have been able to show the applicability of this method to range of different substrates eo give their corresponding esters in moderate to high yields. The challenging esterification reaction of long-chain aliph. alcs. were accomplished by using a P-olefin ligand to control the selectivity. The direct nature of this route and the use of O2 as the oxidant represent a step toward an environmentally benign and sustainable process. Studies into the mechanistic pathway and the improvement of the reaction efficiency are currently underway.
For Cu-catalyzed aerobic oxidative esterification of ethylene glycol with primary or secondary alcohols to a mixture of oxalic acid diesters and byproducts (aldehydes/ketones and homoesterification products), see:
(i) Morino, Y.; Yatabe, T.; Suzuki, K.; Yamaguchi, K. Cu/N-Oxyl-catalyzed aerobic oxidative esterification to oxalic acid diesters from ethylene glycol via highly selective intermolecular alcohol oxidation. Green Chem. 2022, 24, 2017, DOI: 10.1039/D1GC04001DGoogle ScholarThere is no corresponding record for this reference. - 8(a) Oliveira, R. L.; Kiyohara, P. K.; Rossi, L. M. Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticles. Green Chem. 2009, 11, 1366, DOI: 10.1039/b902499aGoogle Scholar8ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVOmtbjO&md5=96af90aefb67ab4153a4f00bc328ece5Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticlesOliveira, Rafael L.; Kiyohara, Pedro K.; Rossi, Liane M.Green Chemistry (2009), 11 (9), 1366-1370CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Me esters were prepd. by the clean, 1-step catalytic esterification of primary alcs. using O2 as a green oxidant and a newly developed SiO2-supported Au nanoparticle catalyst. The catalyst was highly active and selective in a broad range of pressure and temp. At 3 atm O2 and 130°, PhCH2OH was converted to PhCO2Me with 100% conversion and 100% selectivity within 4 h. This catalytic process is much "greener" than the conventional routes, because it avoids the use of stoichiometric environmentally unfriendly oxidants, usually required for alc. oxidn., and the use of strong acids or excess of reactants or const. removal of products required to shift the equil. to the desired esterification product.(b) Nielsen, I. S.; Taarning, E.; Egeblad, K.; Madsen, R.; Christensen, C. H. Direct aerobic oxidation of primary alcohols to methyl esters catalyzed by a heterogeneous gold catalyst. Catal. Lett. 2007, 116, 35, DOI: 10.1007/s10562-007-9086-9Google Scholar8bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXntFOqtbY%253D&md5=8b51e29d995ec2cb499e590a38a563a1Direct aerobic oxidation of primary alcohols to methyl esters catalyzed by a heterogeneous gold catalystNielsen, Inger S.; Taarning, Esben; Egeblad, Kresten; Madsen, Robert; Christensen, Claus H.Catalysis Letters (2007), 116 (1-2), 35-40CODEN: CALEER; ISSN:1011-372X. (Springer)Me esters can be produced in high yields by oxidizing methanolic solns. of primary alcs. with dioxygen over a heterogeneous gold catalyst (Au/TiO2). The versatility of this new methodol. is demonstrated by the fact that alkylic, benzylic, and allylic alcs., as well as alcs. contg. an amine functionality are oxidized in good to excellent yields.
- 9Liu, M.; Zhang, Z.; Liu, H.; Xie, Z.; Mei, Q.; Han, B. Transformation of alcohols to esters promoted by hydrogen bonds using oxygen as the oxidant under metal-free conditions. Sci. Adv. 2018, 4, eaas9319 DOI: 10.1126/sciadv.aas9319Google ScholarThere is no corresponding record for this reference.
- 10(a) Liu, G.; Li, G.; Song, H. Direct Synthesis of Methyl Propionate from n-Propyl Alcohol and Methanol Using Gold Catalysts. Catal. Lett. 2009, 128, 493, DOI: 10.1007/s10562-008-9782-0Google Scholar10ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVCgtLjM&md5=bcd84a112d0eacd65b2f1c580adea995Direct Synthesis of Methyl Propionate from n-Propyl Alcohol and Methanol Using Gold CatalystsLiu, Guangliang; Li, Gang; Song, HaiyanCatalysis Letters (2009), 128 (3-4), 493-501CODEN: CALEER; ISSN:1011-372X. (Springer)Me propionate was prepd. by aerobic oxidn. of PrOH dissolved in MeOH using Au/TiO2 nanocatalysts prepd. by a deposition-pptn. method. Under optimum conditions, the PrOH conversion and product selectivity reached 63% and 99%, resp. The catalyst was stable and could be recovered and reused without significant deactivation.(b) Su, F.-Z.; Ni, J.; Sun, H.; Cao, Y.; He, H.-Y.; Fan, K.-N. Gold Supported on Nanocrystalline β-Ga2O3 as a Versatile Bifunctional Catalyst for Facile Oxidative Transformation of Alcohols, Aldehydes, and Acetals into Esters. Chem.─Eur. J. 2008, 14, 7131, DOI: 10.1002/chem.200800982Google Scholar10bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVGrs7rE&md5=19da49575f24c7d3eca9f361d27489e4Gold supported on nanocrystalline β-Ga2O3 as a versatile bifunctional catalyst for facile oxidative transformation of alcohols, aldehydes, and acetals into estersSu, Fang-Zheng; Ni, Ji; Sun, Hao; Cao, Yong; He, He-Yong; Fan, Kang-NianChemistry - A European Journal (2008), 14 (24), 7131-7135CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Deposition of gold nanoparticles onto nanocryst. β-Ga2O3 results in the formation of a solid bifunctional catalyst that can allow facile, additive-free, aerobic oxidn. of primary alcs., aldehydes, and acetals into their resp. esters in good-to-excellent yields, providing an environmentally benign approach for the direct synthesis of carboxylic esters.(c) Caporaso, M.; Cravotto, G.; Georgakopoulos, S.; Heropoulos, G.; Martina, K.; Tagliapietra, S. Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol. Beilstein J. Org. Chem. 2014, 10, 1454, DOI: 10.3762/bjoc.10.149Google Scholar10chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFSqs7vL&md5=cfa71bd4b52176c69a1fbba7c7548c31Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocolCaporaso, Marina; Cravotto, Giancarlo; Georgakopoulos, Spyros; Heropoulos, George; Martina, Katia; Tagliapietra, SilviaBeilstein Journal of Organic Chemistry (2014), 10 (), 1454-1461, 8 pp.CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)An environmentally friendly microwave-assisted oxidative esterification of alcs. and aldehydes in the presence of mol. oxygen and a heterogeneous catalysis (Pd/C, 5 mol %) is described. This efficient and ligandless conversion procedure does not require the addn. of an org. hydrogen acceptor. The reaction rate is strongly enhanced by mild dielec. heating. Furthermore, it is a versatile green procedure which generally enables the isolation of esters I (R1 = Ph, 4-MeOC6H4, 4-N2OC6H4, etc.; R2 = Me, Et, n-Pr, etc.) to be carried out by simple filtration in almost quant. yields.
- 11Martínez, S.; Veth, L.; Lainer, B.; Dydio, P. Challenges and opportunities in multicatalysis. ACS Catal. 2021, 11, 3891, DOI: 10.1021/acscatal.0c05725Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmtlSktr0%253D&md5=3bbf88e033ec62c77d8306e41b279154Challenges and Opportunities in Multi-CatalysisMartinez, Sebastian; Veth, Lukas; Lainer, Bruno; Dydio, PawelACS Catalysis (2021), 11 (7), 3891-3915CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. Multicatalysis is an emerging field targeting the development of efficient catalytic transformations to quickly convert relatively simple starting materials into more complex value-added products. Within multicatalytic processes either multiple catalysts execute single reactions or precise sequences of multiple catalytic reactions occur in a "one-pot" fashion. Attractively, multicatalytic protocols not only enable transformations that are inaccessible through classic approaches, but also are able to significantly reduce time, waste, and cost of the synthetic processes, making org. synthesis more resources efficient. In this Perspective article, different strategies in multicatalysis that bring distinct challenges and opportunities has been reviewed. The overarching field is divided into three main categories: cooperative, domino, and relay catalysis. Each category is described along with representative examples to highlight its features. Special emphasis is dedicated to relay catalysis, which is further discussed in its subcategories. Lastly, an anal. of systems that incorporate higher levels of complexity and further underscore the potential of multicatalytic systems has been discussed.
- 12(a) Ma, S.; Liu, J.; Li, S.; Chen, B.; Cheng, J.; Kuang, J.; Liu, Y.; Wan, B.; Wang, Y.; Ye, J.; Yu, Q.; Yuan, W.; Yu, S. Development of a General and Practical Iron Nitrate/TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones: Catalysis with Table Salt. Adv. Synth. Catal. 2011, 353, 1005, DOI: 10.1002/adsc.201100033Google Scholar12ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXltVGmt78%253D&md5=65c3939a61295b53b943b8656616eac3Development of a General and Practical Iron Nitrate/TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones: Catalysis with Table SaltMa, Sheng-Ming; Liu, Jin-Xian; Li, Su-Hua; Chen, Bo; Cheng, Jia-Jia; Kuang, Jin-Qiang; Liu, Yu; Wan, Bao-Qiang; Wang, Yu-Li; Ye, Jun-Tao; Yu, Qiong; Yuan, Wei-Ming; Yu, Shi-ChaoAdvanced Synthesis & Catalysis (2011), 353 (6), 1005-1017CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)Oxidn. of alcs. is a fundamental transformation related to our daily life. Traditional approaches with at least one stoichiometric amt. of oxidants are expensive and cause serious environmental burdens. There are many reports on the aerobic oxidn. of simple alcs. such as alkyl or Ph carbinols and allylic alcs., which used oxygen or air as the environmentally benign oxidant forming water as the only byproduct. However, no such protocol has been reported for allenols and propargylic alcs. Thus, it still highly desirable to develop efficient room temp. oxidns. of alcs. with a wide scope including allenols and propargylic alcs. In this paper, an efficient and clean aerobic oxidn. of so far the widest spectrum of alcs. using 1 atm of oxygen or air, producing aldehydes/ketones at room temp. in fairly high isolated yields mostly within a couple of hours is described. It is interesting to observe that the reaction has been efficiently expedited by a catalytic amt. of sodium chloride in easily recoverable 1,2-dichloroethane. A mechanism involving NO and NO2 has been proposed based on the results of the control expts. and GC-MS studies of the in-situ formed gas phase of the reaction mixt.(b) Wang, L.; Shang, S.; Li, G.; Ren, L.; Lv, Y.; Gao, S. Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere. J. Org. Chem. 2016, 81, 2189, DOI: 10.1021/acs.joc.6b00009Google Scholar12bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitlCjtr8%253D&md5=a276aa778ca304c5901bff1e5574c6d5Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient AtmosphereWang, Lianyue; Shang, SenSen; Li, Guosong; Ren, Lanhui; Lv, Ying; Gao, ShuangJournal of Organic Chemistry (2016), 81 (5), 2189-2193CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)We report a new Fe(NO3)3·9H2O/9-azabicyclo[3.3.1]nonan-N-oxyl catalyst system that enables efficient aerobic oxidn. of a broad range of primary and secondary alcs. to the corresponding aldehydes and ketones at room temp. with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliph. alc. oxidn. This procedure can also be scaled up. Kinetic anal. demonstrates that C-H bond cleavage is the rate-detg. step and that cationic species are involved in the reaction.(c) Hong, M.; Min, J.; Wu, S.; Cui, H.; Zhao, Y.; Li, J.; Wang, S. Metal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen Atmosphere. ACS Omega 2019, 4, 7054, DOI: 10.1021/acsomega.9b00391Google Scholar12chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnsFGrtb0%253D&md5=c174245864aacf84a6df4e3fedd7c8cbMetal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen AtmosphereHong, Mei; Min, Jie; Wu, Shuangyan; Cui, Huangui; Zhao, Yuxin; Li, Jiatong; Wang, ShifaACS Omega (2019), 4 (4), 7054-7060CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)Selective synthesis of various versatile compds. from biomass is of great importance to displace traditional fossil fuel resources. Here, homogeneous metal nitrate/TEMPO and metal nitrate/TEMPO/NaNO2 catalyst systems in glacial acetic acid and acetonitrile, resp., have been found highly active and practical sustainable selective oxidn. 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) using pure O2 or even O2 in air as the oxidant. The catalytic methods enable full HMF conversion with a nearly 100% DFF selectivity at 50°C under atm. pressure using a very simple reaction setup and workup. Mechanistic aspects are discussed. The influences of reaction conditions such as different metal catalysts, catalyst loading, solvents and reaction temp. on the promotion effect were studied. Meanwhile, the catalyst systems had also good performance for aerobic oxidn. of other alcs.(d) Jiang, X.; Zhang, J.; Ma, S. Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic Acids. J. Am. Chem. Soc. 2016, 138, 8344, DOI: 10.1021/jacs.6b03948Google Scholar12dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XpvFynt7o%253D&md5=639bfbe022d9bdf9137c221aaaa9bc02Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic AcidsJiang, Xingguo; Zhang, Jiasheng; Ma, ShengmingJournal of the American Chemical Society (2016), 138 (27), 8344-8347CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Oxidn. from alcs. to carboxylic acids, a class of essential chems. in daily life, academic labs., and industry, is a fundamental reaction, usually using at least a stoichiometric amt. of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidn. technol. of alcs. to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amt. each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcs. (also aldehydes) in high yields at room temp. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished.(e) Nutting, J. E.; Mao, K.; Stahl, S. S. Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity. J. Am. Chem. Soc. 2021, 143, 10565, DOI: 10.1021/jacs.1c05224Google Scholar12ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1Wms7fK&md5=2bcfa2ede35251963e96071f7d513426Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox CooperativityNutting, Jordan E.; Mao, Kaining; Stahl, Shannon S.Journal of the American Chemical Society (2021), 143 (28), 10565-10570CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Aerobic alc. oxidns. catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which CuII and the aminoxyl participate together to mediate alc. oxidn. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alc. is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixt. by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NOx-based redox cycle for oxidn. of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alc. oxidn. chemoselectivity and functional group compatibility.(f) Li, J.; Liu, J.; Fu, C.; Ma, S. Fe(III)-Catalyzed Aerobic Oxidation of 1,4-Diols. Chin. J. Chem. 2023, 41, 1963, DOI: 10.1002/cjoc.202200768Google ScholarThere is no corresponding record for this reference.
- 13
For reports on aerobic oxidative cross-esterification of activated benzylic alcohols and cinnamyl alcohols with noble-metal catalysts, see:
(a) Miyamura, H.; Yasukawa, T.; Kobayashi, S. Aerobic oxidative esterification of alcohols catalyzed by polymer-incarcerated gold nanoclusters under ambient conditions. Green Chem. 2010, 12, 776, DOI: 10.1039/b926877dGoogle Scholar13ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXlvVGhs7Y%253D&md5=ce5714b5b9c55221af2dd91e4b5ebb68Aerobic oxidative esterification of alcohols catalyzed by polymer-incarcerated gold nanoclusters under ambient conditionsMiyamura, Hiroyuki; Yasukawa, Tomohiro; Kobayashi, ShuGreen Chemistry (2010), 12 (5), 776-778CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Environmentally benign aerobic oxidn. of alcs. to Me esters catalyzed by polymer-immobilized gold nanoclusters (PI-Au) was developed and reactions proceeded under very mild conditions. The catalyst could be recovered by simple operations without significant loss of activity.(b) Chng, L. L.; Yang, J.; Ying, J. Y. Efficient Synthesis of Amides and Esters from Alcohols under Aerobic Ambient Conditions Catalyzed by a Au/Mesoporous Al2O3 Nanocatalyst. ChemSusChem 2015, 8, 1916, DOI: 10.1002/cssc.201403469Google Scholar13bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnsFClsLg%253D&md5=f452f4f14f71ede01d54aee19f1c884cEfficient synthesis of amides and esters from alcohols under aerobic ambient conditions catalyzed by a Au/mesoporous Al2O3 nanocatalystChng, Leng Leng; Yang, Jinhua; Ying, Jackie Y.ChemSusChem (2015), 8 (11), 1916-1925CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)An efficient heterogeneous mesoporous-alumina-supported gold nanocatalyst was successfully developed for the synthesis of amides e.g.,I and esters via direct amidation of benzyl alcs. with amines and oxidative esterification of alcs. with methanol resp. This protocol had the advantages of simple reaction and high isolated yield under aerobic ambient conditions. Furthermore, the nanocatalyst was stable to air and water and could be recovered and reused easily. The ability of mesoporous-alumina gold nanoparticles to catalyze these reactions under ambient conditions further enhances the sustainability of these chem. processes. The enhanced catalytic activity of Au/mesoporous alumina might be attributed to the presence of neg. charged Au nanoparticles that could promote oxidn. processes as well as the stability of the mesoporous alumina support calcined at a high temp. of 800 °C.(c) Xiao, Q.; Liu, Z.; Bo, A.; Zavahir, S.; Sarina, S.; Bottle, S.; Riches, J. D.; Zhu, H. Catalytic Transformation of Aliphatic Alcohols to Corresponding Esters in O2 under Neutral Conditions Using Visible-Light Irradiation. J. Am. Chem. Soc. 2015, 137, 1956, DOI: 10.1021/ja511619cGoogle Scholar13chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlyks78%253D&md5=68cafade06c11313c5b61f2b07bfab38Catalytic Transformation of Aliphatic Alcohols to Corresponding Esters in O2 under Neutral Conditions Using Visible-Light IrradiationXiao, Qi; Liu, Zhe; Bo, Arixin; Zavahir, Sifani; Sarina, Sarina; Bottle, Steven; Riches, James D.; Zhu, HuaiyongJournal of the American Chemical Society (2015), 137 (5), 1956-1966CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Selective oxidn. of aliph. alcs. under mild and base-free conditions is a challenging process for org. synthesis. Herein, we report a one-pot process for the direct oxidative esterification of aliph. alcs. that is significantly enhanced by visible-light irradn. at ambient temps. The new methodol. uses heterogenerous photocatalysts of gold-palladium alloy nanoparticles on a phosphate-modified hydrotalcite support and mol. oxygen as a benign oxidant. The alloy photocatalysts can absorb incident light, and the light-excited metal electrons on the surface of metal nanoparticles can activate the adsorbed reactant mols. Tuning the light intensity and wavelength of the irradn. can remarkably change the reaction activity. Shorter wavelength light (<550 nm) drives the reaction more efficiently than light of longer wavelength (e.g., 620 nm), esp. at low temps. The phosphate-exchanged hydrotalcite support provides sufficient basicity (and buffer) for the catalytic reactions; thus, the addn. of base is not required. The photocatalysts are efficient and readily recyclable. The findings reveal the first example of using "green" oxidants and light energy to drive direct oxidative esterification of aliph. alcs. under base-free, mild conditions.(d) Mondal, P.; Salam, N.; Mondal, A.; Ghosh, K.; Tuhina, K.; Islam, S. M. A highly active recyclable gold–graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathway. J. Colloid Interface Sci. 2015, 459, 97, DOI: 10.1016/j.jcis.2015.07.072Google Scholar13dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlSksrzL&md5=6a3b007b9b475760579164502bac4a82A highly active recyclable gold-graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathwayMondal, Paramita; Salam, Noor; Mondal, Avijit; Ghosh, Kajari; Tuhina, K.; Islam, Sk. ManirulJournal of Colloid and Interface Science (2015), 459 (), 97-106CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)A graphene based composite with gold nanoparticles has been synthesized via a simple chem. route and the structure and compns. of nanocomposite has been characterized. The catalyst was found to be remarkably stable and active for the oxidative esterification of alcs. under present reaction conditions using mol. oxygen as green oxidant and Suzuki cross-coupling reactions between aryl halides and phenylboronic acids using environmentally friendly water as solvent. The versatility of both the protocols was demonstrated by taking a no. of substrates. This protocol offers several advantages like high yields, clean reactions, recyclability of the catalyst, reaction in water and use of green oxidant. This study suggests graphene, as an economical substitute for carbon nanotubes, could act as a prominent support in heterogeneous catalysis.(e) Tsai, C.-H.; Xu, M.; Kunal, P.; Trewyn, B. G. Aerobic oxidative esterification of primary alcohols over Pd-Au bimetallic catalysts supported on mesoporous silica nanoparticles. Catal. Today 2018, 306, 81, DOI: 10.1016/j.cattod.2017.01.046Google Scholar13ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXisVejsLw%253D&md5=9516b8e7e2c7433299dd37d57ef2a494Aerobic oxidative esterification of primary alcohols over Pd-Au bimetallic catalysts supported on mesoporous silica nanoparticlesTsai, Chih-Hsiang; Xu, Mengze; Kunal, Pranaw; Trewyn, Brian G.Catalysis Today (2018), 306 (), 81-88CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)We have prepd. a series of mesoporous silica nanoparticle (MSN) supported Pd-Au bimetallic catalysts using a newly developed sequential impregnation method. These catalysts were fully characterized by various techniques including nitrogen sorption, powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and high angle annular dark-field scanning transmission electron microscopy (HADDF-STEM). By using this synthetic approach, we obsd. metal nanoparticles (NP) with diams. of 1-2 nm homogeneously supported on the MSN. The catalytic performance of these MSN supported metal NPs was tested by aerobic oxidative esterification in a tandem reaction where primary alcs. are oxidized to their corresponding aldehydes and to esters in a subsequent reaction. We detd. that Pd NPs are very efficient in the first step of oxidn.; however, stagnant in the subsequent oxidn. On the contrary, Au NPs show slow reactivity in converting alcs. to aldehydes, but extraordinarily efficient in the oxidn. of aldehydes to esters. By fine tuning the metal ratio, the bimetallic catalyst exhibits better reactivity and selectivity toward a variety of primary alcs. than the corresponding monometallic catalysts. In addn., we also found that the bimetallic Pd-Au@MSN catalysts can be recycled three times without a significant loss in activity.(f) Li, F.; Li, X.-L.; Li, C.; Shi, J.; Fu, Y. Aerobic oxidative esterification of 5-hydroxymethylfurfural to dimethyl furan-2,5-dicarboxylate by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygen. Green Chem. 2018, 20, 3050, DOI: 10.1039/C8GC01393DGoogle Scholar13fhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtV2gurnI&md5=5b2b411a955cf941ca9e3f0f5d29e055Aerobic oxidative esterification of 5-hydroxymethylfurfural to dimethyl furan-2,5-dicarboxylate by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygenLi, Feng; Li, Xing-Long; Li, Chuang; Shi, Jing; Fu, YaoGreen Chemistry (2018), 20 (13), 3050-3058CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)The conversion of platform mol. 5-hydroxymethylfurfural (HMF) into many value-added derivs. has attracted significant interest. FDCA and its esters are important derivs. of HMF, which can be used as polyester monomers and pharmaceutical intermediates. In this paper, oxidative esterification of 5-HMF has been carried out by using homogeneous and heterogeneous PdCoBi/C catalysts under atm. oxygen. The effect of reaction conditions on product distribution has been studied under both homogeneous and heterogeneous catalytic conditions. The highest yields of oxidative esterification products are obtained at 93% and 96% by using homogeneous and heterogeneous PdCoBi/C catalysts, resp. The catalysts are characterized by XPS and powder X-ray diffraction (XRD). The catalytic system has better compatibility according to the expansion of the substrate. A reaction mechanism is proposed, and recycle expts. are also conducted.(g) Salam, N.; Banerjee, B.; Roy, A. S.; Mondal, P.; Roy, S.; Bhaumik, A.; Islam, S. M. Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcohols. Appl. Catal., A 2014, 477, 184, DOI: 10.1016/j.apcata.2014.03.014Google Scholar13ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmslKhs74%253D&md5=70a3680cb2fb00a3b03380e7886753f4Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcoholsSalam, Noor; Banerjee, Biplab; Roy, Anupam Singha; Mondal, Paramita; Roy, Susmita; Bhaumik, Asim; Islam, Sk. ManirulApplied Catalysis, A: General (2014), 477 (), 184-194CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Silver nanoparticles (Ag-NPs) have been finely dispersed at the mesoporous org. polymer via post-synthetic chem. grafting over mesoporous poly-triallylamine (MPTA-1). The resulting Ag-MPTA-1 nanomaterial has been characterized by elemental anal., powder x-ray diffraction (x-ray diffraction), TEM, Fourier transform IR spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), thermogravimetric anal. (TGA), EPR spectroscopy and AAS elemental anal. The Ag-MPTA-1 acts as an efficient heterogeneous nanocatalyst in the redn. of substituted nitrobenzenes via transfer hydrogenation. The material also showed excellent catalytic activity in one-step catalytic oxidative esterification of primary alcs. using mol. oxygen as a green oxidant. The catalyst is air-stable, inexpensive, easy to prep. and reused several times without significant decrease in activity and selectivity.(h) Gowrisankar, S.; Neumann, H.; Beller, M. General and Selective Palladium-Catalyzed Oxidative Esterification of Alcohols. Angew. Chem., Int. Ed. 2011, 50, 5139, DOI: 10.1002/anie.201008035Google Scholar13hhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtFymtLg%253D&md5=798061c7944dc7f22ce3ae3c391a6474General and Selective Palladium-Catalyzed Oxidative Esterification of AlcoholsGowrisankar, Saravanan; Neumann, Helfried; Beller, MatthiasAngewandte Chemie, International Edition (2011), 50 (22), 5139-5143CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)New palladium-catalyzed oxidative esterification reactions of primary benzylic alcs. with dioxygen as benign oxidant is described. E.g., in presence of Pd(OAc)2 and the ligand cataCXiumA, oxidative esterification of BnOH with 1-pentanol gave 88% pentyl benzoate. Both oxidative homocoupling reactions as well as cross-esterifications of benzyl alcs. with various aliph. alcs. proceed under mild conditions (50-100°C, 1 bar oxygen) to give the corresponding esters with water as the only side-product.(i) Luo, F.; Pan, C.; Cheng, J.; Chen, F. Palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols. Tetrahedron 2011, 67, 5878, DOI: 10.1016/j.tet.2011.06.060Google ScholarThere is no corresponding record for this reference.(j) Bai, X.-F.; Ye, F.; Zheng, L.-S.; Lai, G.-Q.; Xia, C.-G.; Xu, L.-W. Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with air. Chem. Commun. 2012, 48, 8592, DOI: 10.1039/c2cc34117dGoogle Scholar13jhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFaju7jE&md5=445a4c84050a74e83c3f91577be27845Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with airBai, Xing-Feng; Ye, Fei; Zheng, Long-Sheng; Lai, Guo-Qiao; Xia, Chun-Gu; Xu, Li-WenChemical Communications (Cambridge, United Kingdom) (2012), 48 (68), 8592-8594CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)In a palladium-catalyzed oxidative esterification, hydrosilane can serve as an activator of palladium catalyst with bismuth, thus leading to a novel ligand- and silver-free palladium catalyst system for facile oxidative esterification of a variety of benzylic alcs. in good yields.(k) Hu, Y.; Li, B. Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions. Tetrahedron 2017, 73, 7301, DOI: 10.1016/j.tet.2017.11.025Google ScholarThere is no corresponding record for this reference. - 14
For the reports on Pd-catalyzed aerobic oxidative cross-esterification with the promotion of bases, see:
Powell, A. B.; Stahl, S. S. Aerobic Oxidation of Diverse Primary Alcohols to Methyl Esters with a Readily Accessible Heterogeneous Pd/Bi/Te Catalyst. Org. Lett. 2013, 15, 5072, DOI: 10.1021/ol402428eGoogle Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVygu7fP&md5=52d3ff7d8ff29f45324ed26bfadc4a74Aerobic Oxidation of Diverse Primary Alcohols to Methyl Esters with a Readily Accessible Heterogeneous Pd/Bi/Te CatalystPowell, Adam B.; Stahl, Shannon S.Organic Letters (2013), 15 (19), 5072-5075CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)Efficient aerobic oxidative Me esterification of primary alcs. has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate scope and is effective with both activated (benzylic) and unactivated (aliph.) alcs. bearing diverse functional groups. Safety: fire hazard in addn. of neutral MeOH to Pd/charcoal. - 15(a) Huang, X.; Ma, S. Allenation of terminal alkynes with aldehydes and ketones. Acc. Chem. Res. 2019, 52, 1301, DOI: 10.1021/acs.accounts.9b00023Google Scholar15ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnt1Ght7g%253D&md5=2419c15230a0c423f0fef1758a3aa26eAllenation of Terminal Alkynes with Aldehydes and KetonesHuang, Xin; Ma, ShengmingAccounts of Chemical Research (2019), 52 (5), 1301-1312CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. So far, over 150 natural products and pharmaceuticals contg. an allene moiety have been identified. During the last two decades, allenes have also been demonstrated as synthetically versatile starting materials in org. synthesis. In comparison to alkenes and alkynes, allenes are unique unsatd. hydrocarbons due to their axial chirality, which could be transformed to central chirality via chirality transfer to provide an irreplaceable entry to chiral mols. Thus, methods for allene synthesis from readily available chems. are of great interest. In 1979, Crabb´e et al. reported the first CuBr-mediated allenation of terminal alkynes (ATA reaction) to form monosubstituted allenes from 1-alkynes and paraformaldehyde in the presence of diisopropylamine. During the following 30 years, the ATA reactions were limited to paraformaldehyde. This Account describes our efforts toward the development of ATA reactions in the last ten years. First, we improved the yields and scope greatly for the synthesis of monosubstituted allenes by modifying the original Crabb´e recipe. Next we developed the ZnI2-promoted or CuI-catalyzed ATA reactions for the synthesis of 1,3-disubstituted allenes from terminal alkyne and normal aldehydes. Furthermore, we first realized the CdI2-promoted ATA reaction of ketones with pyrrolidine as the matched amine for the prepn. of trisubstituted allenes. Due to the toxicity of CdI2, we also developed two alternative approaches utilizing CuBr/ZnI2 or CuI/ZnBr2/Ti(OEt)4. The asym. version of ATA reactions for the synthesis of optically active 1,3-disubstituted allenes has also been achieved in this group with two strategies. One is called "chiral ligand" strategy, using terminal alkynes, aldehydes, and nonchiral amine with the assistance of a proper chiral ligand. The other is the "chiral amine" strategy, applying terminal alkynes, aldehydes, and chiral amines such as (S)- or (R)-α,α-diphenylprolinol or (S)- or (R)-α,α-dimethylprolinol. Optically active 1,3-disubstituted allenes contg. different synthetically useful functionalities such as alc., amide, sulfamide, malonate, carboxylate, and carbohydrate units could be prepd. without protection with the newly developed CuBr2-catalyzed chiral amine strategy. Recently, we have applied these enantioselective allenation of terminal alkyne (EATA) reactions to the syntheses of some natural allenes such as laballenic acid, insect pheromone, Me (R)-8-hydroxyocta-5,6-dienoate, phlomic acid, and lamenallenic acid, as well as some non-allene natural γ-butyrolactones such as xestospongienes (E, F, G, and H), (R)-4-tetradecalactone, (S)-4-tetradecalactone, (R)-γ-palmitolactone, and (R)-4-decalactone.(b) Huang, X.; Cao, T.; Han, Y.; Jiang, X.; Lin, W.; Zhang, J.; Ma, S. General CuBr2-catalyzed highly enantioselective approach for optically active allenols from terminal alkynols. Chem. Commun. 2015, 51, 6956, DOI: 10.1039/C5CC00697JGoogle Scholar15bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXkt1Ogu78%253D&md5=bd18b9f37a3e6e53c59e22b5595402e9General CuBr2-catalyzed highly enantioselective approach for optically active allenols from terminal alkynolsHuang, Xin; Cao, Tao; Han, Yulin; Jiang, Xingguo; Lin, Weilong; Zhang, Jiasheng; Ma, ShengmingChemical Communications (Cambridge, United Kingdom) (2015), 51 (32), 6956-6959CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)It was reported that a CuBr2-catalyzed approach for a highly enantioselective synthesis (93-99% ee) of allenols from aldehydes and terminal alkynols with the abs. configuration being controlled by applying readily available (R)- or (S)-α,α-diphenylprolinol.(c) Tang, X.; Huang, X.; Cao, T.; Han, Y.; Jiang, X.; Lin, W.; Tang, Y.; Zhang, J.; Yu, Q.; Fu, C.; Ma, S. CuBr2-catalyzed enantioselective routes to highly functionalized and naturally occurring allenes. Org. Chem. Front. 2015, 2, 688, DOI: 10.1039/C5QO00084JGoogle Scholar15chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmt1WqtrY%253D&md5=a292c6014497d91ebacf51139c17d95aCuBr2-catalyzed enantioselective routes to highly functionalized and naturally occurring allenesTang, Xinjun; Huang, Xin; Cao, Tao; Han, Yulin; Jiang, Xingguo; Lin, Weilong; Tang, Yang; Zhang, Jiasheng; Yu, Qiong; Fu, Chunling; Ma, ShengmingOrganic Chemistry Frontiers (2015), 2 (6), 688-691CODEN: OCFRA8; ISSN:2052-4129. (Royal Society of Chemistry)The CuBr2-catalyzed approach for highly enantioselective synthesis (90-98% ee) of allenes bearing a very broad array of unmasked synthetically attractive functionalities from aldehydes and terminal alkynyl bearing reactive functionalities with the abs. configuration controlled by applying readily available (R)- or (S)-α,α-diphenylprolinol is described. Following this protocol, the highly enantioselective synthesis of some naturally occurring allenes loaded with reactive functionalities becomes simple: a terminal alkyne plus an aldehyde. In comparison, they were reported to be synthesized either from similar level generic chems. with much more steps or in lower ees.
- 16Aitzetmüller, K.; Tsevegsüren, N.; Vosmann, K. A New Allenic Fatty Acid in Phlomis (Lamiaceae) Seed Oil. Lipid/Fett 1997, 99, 74, DOI: 10.1002/lipi.19970990304Google ScholarThere is no corresponding record for this reference.
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Abstract 摘要
Figure 1 图 1
Figure 1. Approaches for the synthesis of esters. (A) Selected important methyl esters. (B) The state of the art of aerobic oxidation of primary alcohols. (C) Traditional approaches for the synthesis of esters. (D) The challenges for the esterification of two alcohols. (E) The concept of relay catalysis for selective aerobic esterification. (F) This work: aerobic cross esterification of primary alcohols with methanol.
图 1. 酯合成方法。(A) 选择重要的甲酯。(B) 一级醇的空气氧化的最新技术。(C) 酯合成的传统方法。(D) 两种醇酯化的挑战。(E) 选择性空气酯化的中继催化概念。(F) 本研究:一级醇与甲醇的空气交叉酯化。Scheme 1
Scheme 1. Substrate ScopeaaThe reaction was conducted with 1 (1.0 mmol), MeOH (5.0 mmol), Fe(NO3)3·9H2O (6 mol %), TEMPO (5 mol %), and BiCl3 (10 mol %) in 3 mL of DCE at 50 °C for 48 h with an O2 balloon.
b4 mL of DCE were used.
cThe reaction time was 60 h, 47% isolated yield.
dNMR yield under standard conditions.
e8 mol % each of Fe(NO3)3·9H2O and TEMPO were used.
f4 mmol of MeOH were used.
g8 mol % of Fe(NO3)3·9H2O was used.
h5 mmol scale reaction.
i10 mol % of TEMPO was used.
jNMR yield of the aldehydes in parentheses determined by 1H NMR analysis using dibromomethane as the internal standard.
kNMR yield of the acetal determined by 1H NMR analysis using dibromomethane as the internal standard.
References
ARTICLE SECTIONSThis article references 16 other publications.
- 1United Nations World Commission on Environment and Development (WCED). Our Common Future (The Brundtland Report), Annex to General Assembly document A/42/427; Oxford Univ. Press: Oxford, 1987.There is no corresponding record for this reference.
- 2Poliakoff, M.; Licence, P. Green chemistry. Nature 2007, 450, 810, DOI: 10.1038/450810a2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtl2gsbfK&md5=55e399471ef1272c0e6b6124d2e55b63Green chemistryPoliakoff, Martyn; Licence, PeteNature (London, United Kingdom) (2007), 450 (7171), 810-812CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Modern life depends on the petrochem. industry - most drugs, paints and plastics derive from oil. But current processes for making chem. products are not sustainable in terms of resources and environmental impact. Green chem. aims to tackle this problem, and real progress is being made.
- 3
For selected seminal reports on aerobic oxidation of alcohols via transition-metal catalysis, see the following articles. With Pd catalysts:
(a) Blackburn, T. F.; Schwartz, J. Homogeneous catalytic oxidation of secondary alcohols to ketones by molecular oxygen under mild conditions. J. Chem. Soc., Chem. Commun. 1977, 157, DOI: 10.1039/c39770000157There is no corresponding record for this reference.(b) Fiege, H.; Wedemeyer, K. Activation of Oxidations with Oxygen on Platinum Metals Using the Example of the Conversion of 2-Phenoxyethanols to Phenoxyacetic Acids. Angew. Chem., Int. Ed. Engl. 1981, 20, 783, DOI: 10.1002/anie.198107831There is no corresponding record for this reference.With Au catalysts:
(c) Milone, C.; Ingoglia, R.; Neri, G.; Pistone, A.; Galvagno, S. Gold catalysts for the liquid phase oxidation of o-hydroxybenzyl alcohol. Appl. Catal., A 2001, 211, 251, DOI: 10.1016/S0926-860X(00)00875-93chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXisVWisLc%253D&md5=36d39c244b309ddc162e3155d7b39260Gold catalysts for the liquid phase oxidation of o-hydroxybenzyl alcoholMilone, C.; Ingoglia, R.; Neri, G.; Pistone, A.; Galvagno, S.Applied Catalysis, A: General (2001), 211 (2), 251-257CODEN: ACAGE4; ISSN:0926-860X. (Elsevier Science B.V.)Gold on iron oxide catalysts have been investigated in the liq. phase oxidn. of o-hydroxybenzyl alc. (salicylic alc.) under mild conditions. The presence of gold strongly enhances the catalytic activity of iron oxide, which is practically inactive under the same reaction conditions. The liq. phase oxidn. of salicylic alc. follows a first order reaction rate law with respect to the org. substrate. The order of reaction with respect to the oxygen partial pressure is close to zero. The catalytic activity increases with the gold loading. The oxidn. of salicylic alc. on the catalysts with low gold loading leads to the formation of salicylic aldehyde as the main reaction product. A small amt. of salicylic acid was also obtained. On the catalysts with higher gold loading a progressive decrease of the yield to salicylic aldehyde with the conversion level occurs. When the reaction is carried out using benzene as solvent, the salicylic aldehyde is the end products on all the catalysts investigated regardless of the gold content.(d) Prati, L.; Rossi, M. Gold on carbon as a new catalyst for selective liquid phase oxidation of diols. J. Catal. 1998, 176, 552, DOI: 10.1006/jcat.1998.20783dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXjvFemsr0%253D&md5=f4f0bd7c492a3e299039327b621a7a84Gold on carbon as a new catalyst for selective liquid phase oxidation of diolsPrati, Laura; Rossi, MicheleJournal of Catalysis (1998), 176 (2), 552-560CODEN: JCTLA5; ISSN:0021-9517. (Academic Press)Catalytic oxidn. of vicinal diols to α-hydroxy carboxylates with O in alk. soln. was performed by using Au-based catalysts. The influence of support and prepn. method on both activity and selectivity was studied. Under mild conditions, high selectivities were achieved toward monooxygenation of ethylene glycol and propylene glycol with high diol conversion. The racemization of optically active propylene glycol during its oxidn. as well as isotopic H-D exchange expts. allowed us to deduce features of the mechanism. The recycling of Au/C catalyst revealed its good resistance toward deactivation.With Ru catalysts:
(e) Matsumoto, M.; Ito, S. Ruthenium-catalysed oxidation of allyl alcohols by molecular oxygen. J. Chem. Soc., Chem. Commun. 1981, 907, DOI: 10.1039/c39810000907There is no corresponding record for this reference.(f) Murahashi, S.; Naota, T.; Hirai, N. Aerobic oxidation of alcohols with ruthenium-cobalt bimetallic catalyst in the presence of aldehydes. J. Org. Chem. 1993, 58, 7318, DOI: 10.1021/jo00078a0023fhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXhs1aqs7Y%253D&md5=ff17b7a32d9093577132e9c5e74bf3feAerobic oxidation of alcohols with ruthenium-cobalt bimetallic catalyst in the presence of aldehydesMurahashi, Shunichi; Naota, Takeshi; Hirai, NaruhisaJournal of Organic Chemistry (1993), 58 (26), 7318-19CODEN: JOCEAH; ISSN:0022-3263.Aerobic oxidn. of alcs. proceeds highly efficiently at room temp. Thus, various aliph. and arom. alcs. can be oxidized with mol. O in the presence of a 1:1 mixt. of RuCl3 and Co(OAc)2 catalyst and an aldehyde at room temp. under O2 atmosphere (1 atm) to give the corresponding ketones. Similar treatment of primary alcs. gives the corresponding carboxylic acids. This reaction is highly convenient because of its simple operation, mild reaction conditions, and high efficiency. The reaction can be rationalized by assuming 2 sequential pathways; first, formation of peracids by cobalt-mediated radical chain reaction of aldehydes with mol. O, second, Ru-catalyzed oxidn. of alcs. with the peracids thus formed.With Cu catalysts:
(g) Semmelhack, M. F.; Schmid, C. R.; Cortes, D. A.; Chou, C. S. Oxidation of alcohols to aldehydes with oxygen and cupric ion, mediated by nitrosonium ion. J. Am. Chem. Soc. 1984, 106, 3374, DOI: 10.1021/ja00323a0643ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2cXitVylsbc%253D&md5=5d64f572e776e56a17fe1d8022df097aOxidation of alcohols to aldehydes with oxygen and cupric ion, mediated by nitrosonium ionSemmelhack, M. F.; Schmid, Christopher R.; Cortes, David A.; Chou, Chuen S.Journal of the American Chemical Society (1984), 106 (11), 3374-6CODEN: JACSAT; ISSN:0002-7863.Reaction of CuCl2 with the readily available free radical 2,2,6,6-tetramethylpiperidin-1-oxy (TEMPO) produces cuprous ion and the corresponding nitrosonium ion. In this redox system, using CaH2 to scavenge acid as it forms, primary satd., allylic, and benzylic alcs. are converted to aldehydes in high yield at 25°. For the more reactive substrates, allylic and benzylic alcs., the oxidn. can be operated in an efficient catalytic cycle, using O as the oxidizing agent with CuCl and TEMPO present in 2-10 mol %. In this case, no net formation of acid occurs and no base is needed. Representative allylic and benzylic alcs. give the aldehydes in 85-97% yield. Strong preference for primary over secondary allylic alcs. is demonstrated by the lack of reactivity of 2-cyclohexenol and by selective oxidn. of 1,8-nonanediol to 8-hydroxynonanal.(h) Yu, Y.; Zhai, D.; Zhou, Z.; Jiang, S.; Qian, H.; Ma, S. Copper-catalyzed aerobic oxidation of primary alcohols to carboxylic acids. Chem. Commun. 2023, 59, 5281, DOI: 10.1039/D3CC00963GThere is no corresponding record for this reference.With Fe catalysts:
(i) Martín, S. E.; Suárez, D. o. F. Catalytic aerobic oxidation of alcohols by Fe(NO3)3–FeBr3. Tetrahedron Lett. 2002, 43, 4475, DOI: 10.1016/S0040-4039(02)00829-8There is no corresponding record for this reference.(j) Naik, R.; Joshi, P.; Deshpande, R. K. Polymer encapsulation of metallophthalocyanines: efficient catalysts for aerobic oxidation of alcohols. Catal. Commun. 2004, 5, 195, DOI: 10.1016/j.catcom.2004.02.0023jhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhvV2jt7c%253D&md5=79c4c4b54ecdde65d758322f2a0bd673Polymer encapsulation of metallophthalocyanines: efficient catalysts for aerobic oxidation of alcoholsNaik, Rajan; Joshi, Padmakar; Deshpande, Rajesh K.Catalysis Communications (2004), 5 (4), 195-198CODEN: CCAOAC; ISSN:1566-7367. (Elsevier Science B.V.)Metallophthalocynines (MPcs) of iron, cobalt and copper have been successfully encapsulated for the first time on polystyrene matrix, rendering them highly dispersible in common org. solvents. These catalysts were characterized by diffuse reflectance UV-Vis spectra as well as FT-IR spectroscopy. The encapsulated metallophthalocyanines (MCMPcs) were found to be stable and more active than their unencapsulated counterparts. These encapsulated catalysts showed enhanced activity for aerobic oxidn. of alcs. mimicking cytochrome P 450 dependent mono oxygenases. These catalysts not only have high turnover frequencies but could be recovered quant. by simple filtration and reused without loss of activity. Phenethyl alc., benzoin, mandelic acid, and benzyl alc. were oxidized by O in the presence of polystyrene-microencapsulated metallophthalocynines of iron, cobalt, or copper, and KOH in toluene at reflux to acetophenone, benzil, benzoylformic acid, and benzoic acid, resp., in 90-96% yields. - 4
For selected books on oxidation of alcohols, see:
(a) Tojo, G.; Fernández, M. Oxidation of alcohols to aldehydes and ketones: A guide to current common practice; Springer: New York, 2006.There is no corresponding record for this reference.(b) Tojo, G.; Fernández, M. Oxidation of primary alcohols to carboxylic acids: A guide to current common practice; Springer: New York, 2007.There is no corresponding record for this reference.For selected recent reviews on aerobic oxidation of alcohols, see:
(c) Parmeggiani, C.; Matassini, C.; Cardona, F. A step forward towards sustainable aerobic alcohol oxidation: new and revised catalysts based on transition metals on solid supports. Green Chem. 2017, 19, 2030, DOI: 10.1039/C7GC00406K4chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXkvF2ku7o%253D&md5=49810f57b564f65650ac9364ad86fad6A step forward towards sustainable aerobic alcohol oxidation: new and revised catalysts based on transition metals on solid supportsParmeggiani, C.; Matassini, Camilla; Cardona, F.Green Chemistry (2017), 19 (9), 2030-2050CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. T. He oxidn. of alcs. is a reaction under continuous investigation, due to the importance of oxidn. products and the necessity to perform it in a more sustainable way with respect to traditional procedures. In particular, the combination of a metal catalyst with mol. oxygen or air represents one of the best alternatives in this field. New catalysts are continuously proposed in the literature, and it is not often easy to compare their performances owing to the great amt. of examples reported. Heterogeneous catalysts represent the best soln. to heavy metal contamination of the products, provided that leaching has not occurred. Moreover, they ideally should be recovered without deactivation and reused after reaction. The employment of air or oxygen in non-flammable solvents (ideally, water) is also highly appreciated, for safety reasons. We have tried in this review to focus on some very recent reports on solid supported transition metal catalysts that strive to follow these principles thus performing oxidn. in a more sustainable way while guaranteeing an acceptable substrate scope for synthetic utility.(d) Hazra, S.; Malik, E.; Nair, A.; Tiwari, V.; Dolui, P.; Elias, A. J. Catalytic Oxidation of Alcohols and Amines to Value-Added Chemicals using Water as the Solvent. Chem.─Asian J. 2020, 15, 1916, DOI: 10.1002/asia.202000299There is no corresponding record for this reference.(e) An, G.; Zhang, X.; Zhang, C.; Gao, H.; Liu, S.; Qin, G.; Qi, H.; Kasemchainan, J.; Zhang, J.; Wang, G. Metal-organic-framework-based materials as green catalysts for alcohol oxidation. Chin. J. Catal. 2023, 50, 126, DOI: 10.1016/S1872-2067(23)64451-14ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXhs1ynsb3F&md5=b1996f0df41a2f3edd6ce3baf34533ddMetal-organic-framework-based materials as green catalysts for alcohol oxidationAn, Guoqing; Zhang, Xiaowei; Zhang, Canyang; Gao, Hongyi; Liu, Siqi; Qin, Geng; Qi, Hui; Kasemchainan, Jitti; Zhang, Jianwei; Wang, GeChinese Journal of Catalysis (2023), 50 (), 126-174CODEN: CJCHCI; ISSN:1872-2067. (Elsevier B.V.)A review. The selective oxidn. of alcs. is widely regarded as one of the most important reactions in org. synthesis. Although efficient and environmentally friendly catalysts for alc. oxidn. are highly desirable, their development remains an enormous challenge. Metal-org. framework (MOF)-based catalysts have demonstrated great potential in the catalytic oxidn. of alcs. and have remarkably progressed in the past few decades owing to their advantages of large surface area, tunable porous structure, abundant accessible active sites, and ease of reuse and recycling. In this review, recent representative results of the catalytic oxidn. of alcs. by MOF-based materials are summarized and classified according to the type of material and reaction, such as pristine MOFs, MOF composites, and MOF derivs. for traditional thermal catalysis, photo-assisted catalysis, and electro-assisted catalysis. Each catalytic system is described in detail from multiple aspects, including the materials synthesis process, catalytic performance, alc. oxidn. mechanisms, and material stability. Thus, the aims of this review are to identify potentially efficient, green, and reusable MOF-based catalytic systems and to provide new insights for the further development of catalytic alc. oxidn. to obtain the target orgs. - 5(a) Otera, J.; Nishikido, J. Esterification: Method, Reactions, and Applications; Wiley-VCH: Weinheim, 2010.There is no corresponding record for this reference.(b) Carey, F. A.; Sundbery, R. G. Advanced Organic Chemistry, Part B: Reactions and Synthsis, 5th ed.; Springer: New York, 2007.There is no corresponding record for this reference.(c) Ekoue-Kovi, K.; Wolf, C. One-Pot Oxidative Esterification and Amidation of Aldehydes. Chem.─Eur. J. 2008, 14, 6302, DOI: 10.1002/chem.2008003535chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXps1Cjtr0%253D&md5=d7b22e7a57ae650b6afe0f740531acd1One-pot oxidative esterification and amidation of aldehydesEkoue-Kovi, Kekeli; Wolf, ChristianChemistry - A European Journal (2008), 14 (21), 6302-6315CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. During recent years, the direct transformation of aldehydes into esters or amides developed into a vigorous research area and powerful one-pot oxidative esterification and amidation procedures were reported. Several concepts that are often complementary in substrate scope, functional group tolerance, and reaction outcome have emerged, thus providing a wide range of alternatives to classical ester and amide synthesis via carboxylic acid intermediates.(d) Tang, S.; Yuan, J.; Liu, C.; Lei, A. Direct oxidative esterification of alcohols. Dalton Trans. 2014, 43, 13460, DOI: 10.1039/C4DT01133C5dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1WjsrbJ&md5=7d815ab54a52d282ce1d52d9f15e7087Direct oxidative esterification of alcoholsTang, Shan; Yuan, Jiwen; Liu, Chao; Lei, AiwenDalton Transactions (2014), 43 (36), 13460-13470CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)A review. Esterification is a fundamental transformation in chem. Traditional esterification only largely occurs between carboxylic acid derivs. and alcs., and often involves multistep processes. Developments in the transition-metal-catalyzed and metal-free direct esterification of alcs. under oxidative conditions has opened a door to the efficient, sustainable and environmentally friendly synthesis of esters from readily available materials. This Perspective gives an overview which covers the recent development of this emerging field.
- 6
For a seminal report on dehydrogenative esterification of primary alcohols, see:
Zhang, J.; Leitus, G.; Ben-David, Y.; Milstein, D. Facile Conversion of Alcohols into Esters and Dihydrogen Catalyzed by New Ruthenium Complexes. J. Am. Chem. Soc. 2005, 127, 10840, DOI: 10.1021/ja052862b6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmt1ansLk%253D&md5=364eb680398a2c200d0d2e15eb245a53Facile Conversion of Alcohols into Esters and Dihydrogen Catalyzed by New Ruthenium ComplexesZhang, Jing; Leitus, Gregory; Ben-David, Yehoshoa; Milstein, DavidJournal of the American Chemical Society (2005), 127 (31), 10840-10841CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)An efficient, environmentally benign method for the prepn. of esters from alcs. under mild, neutral conditions without the need for carboxylic acid derivs. and condensing agents was developed. Catalyst design, based on new Ru(II) hydrido carbonyl complexes incorporating electron-rich bis(phosphinomethyl)pyridine (PNP) and aminomethylphosphinomethylpyridine (PNN) ligands resulted in Ru(PNP/PNN)(CO)Cl(H) and Ru(PNN)(CO)H the latter of which (PNN = diethylaminomethylbis(tert-butyl)phosphinomethylpyridine) is an outstanding catalyst for the dehydrogenation of primary alcs. to esters and H2 under neutral conditions. - 7(a) Hao, Y.; Chong, Y.; Li, S.; Yang, H. Controlled Synthesis of Au Nanoparticles in the Nanocages of SBA-16: Improved Activity and Enhanced Recyclability for the Oxidative Esterification of Alcohols. J. Phys. Chem. C 2012, 116, 6512, DOI: 10.1021/jp20932527ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XosFChsw%253D%253D&md5=96b68984de2c190ee9f69fa8882aa6baControlled Synthesis of Au Nanoparticles in the Nanocages of SBA-16: Improved Activity and Enhanced Recyclability for the Oxidative Esterification of AlcoholsHao, Yajuan; Chong, Yanzhu; Li, Shuru; Yang, HengquanJournal of Physical Chemistry C (2012), 116 (11), 6512-6519CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Au nanoparticles with different sizes were introduced into the nanocages of a mesoporous material SBA-16 with the aid of chem. modification, leading to new Au-supported catalysts Au/SBA-16. These catalysts were characterized with Fourier transform IR spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microspectroscopy (TEM), N2 sorption, and X-ray photoelectron microspectroscopy (XPS). These results revealed that uniform Au nanoparticles with sizes of a few nanometers were successfully positioned inside the nanocages of SBA-16. Such catalysts were catalytically active in the oxidative esterification of various alcs. even including less reactive straight-chain alcs. It was found that the activity of this catalyst strongly depended on the Au loading, and the Au loading of 5 wt % (corresponding to Au particles of 2-3 nm in sizes) led to the highest activity. Its activity was much higher than those of the analogous catalysts prepd. from com. silica gel as well as SBA-15. Furthermore, Au/SBA-16 could be reused at least eight reaction cycles without significant decrease in activity and selectivity. Its recyclability was much superior to that of the catalyst derived from com. silica gel. The underlying reason may be that the unique nanostructure of SBA-16 can effectively prevent the growth of Au nanoparticles into less active, larger particles, as evidenced from TEM investigations. This study not only supplies a new, active, recoverable catalyst for the green transformations of alcs. to esters but also demonstrates that the three-dimensional mesoporous cage-like material SBA-16 has a superior ability in reducing the diffusion resistance and stabilizing metal nanoparticles against growth.(b) Parreira, L. A.; Bogdanchikova, N.; Pestryakov, A.; Zepeda, T. A.; Tuzovskaya, I.; Farías, M. H.; Gusevskaya, E. V. Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcohol. Appl. Catal., A 2011, 397, 145, DOI: 10.1016/j.apcata.2011.02.0287bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkvVSrsLk%253D&md5=d66940b52cbb1b3d7d1290ed81ade9c6Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcoholParreira, Luciana A.; Bogdanchikova, Nina; Pestryakov, Alexey; Zepeda, T. A.; Tuzovskaya, Inga; Farias, M. H.; Gusevskaya, Elena V.Applied Catalysis, A: General (2011), 397 (1-2), 145-152CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)The materials contg. gold nanoparticles supported on pure and Ce, Ti, or Fe-modified hexagonal mesoporous silica were prepd. and their structural and electronic properties were studied by x-ray diffraction, TEM, XPS, and N2 adsorption techniques. The materials were shown to be effective heterogeneous catalysts for the liq.-phase aerobic oxidn. of benzyl alc. in methanol solns. It was found that the modifiers significantly improve the catalytic properties of supported gold particles and allow performing the selective one-pot oxidative esterification of benzyl alc. resulting in Me benzoate. The modified catalysts exhibited high activity (turnover frequencies of up to ∼1000 h-1), selectivity to Me benzoate (up to 95%), and stability (turnover nos. of up to ∼4300). Ce and Ti were found to be more effective promoters as compared with Fe in terms of catalyst stability.(c) Liu, P.; Li, C.; Hensen, E. J. M. Efficient Tandem Synthesis of Methyl Esters and Imines by Using Versatile Hydrotalcite-Supported Gold Nanoparticles. Chem.─Eur. J. 2012, 18, 12122, DOI: 10.1002/chem.2012020777chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtF2nsbrM&md5=3b4944151d526c4b1c35d25768c343c2Efficient tandem synthesis of methyl esters and imines by using versatile hydrotalcite-supported gold nanoparticlesLiu, Peng; Li, Can; Hensen, Emiel J. M.Chemistry - A European Journal (2012), 18 (38), 12122-12129, S12122/1-S12122/8CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Efficient basic hydrotalcite (HT)-supported gold nanoparticle (AuNP) catalysts were developed for the aerobic oxidative tandem synthesis of Me esters and imines from primary alcs. catalyzed under mild and sol.-base-free conditions. The catalytic performance can be fine-tuned for these cascade reactions by simple adjustment of the Mg/Al at. ratio of the HT support. The one-pot synthesis of Me esters benefits from high basicity (Mg/Al=5), whereas moderate basicity greatly improves imine selectivity (Mg/Al=2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies showed a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidn. of the starting alc. but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the compn. of the support has been shown to yield optimum AuNP catalysts for different tandem reactions. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.(d) Buonerba, A.; Noschese, A.; Grassi, A. Highly Efficient Direct Aerobic Oxidative Esterification of Cinnamyl Alcohol with Alkyl Alcohols Catalysed by Gold Nanoparticles Incarcerated in a Nanoporous Polymer Matrix: A Tool for Investigating the Role of the Polymer Host. Chem.─Eur. J. 2014, 20, 5478, DOI: 10.1002/chem.201303880There is no corresponding record for this reference.(e) Wei, H.; Li, J.; Yu, J.; Zheng, J.; Su, H.; Wang, X. Gold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditions. Inorg. Chim. Acta 2015, 427, 33, DOI: 10.1016/j.ica.2014.11.0247ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1SmtA%253D%253D&md5=97d3df8ecca06b36d976e2fcfc660caeGold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditionsWei, Huili; Li, Jingyi; Yu, Jing; Zheng, Jianwei; Su, Haiquan; Wang, XiaojingInorganica Chimica Acta (2015), 427 (), 33-40CODEN: ICHAA3; ISSN:0020-1693. (Elsevier B.V.)Gold nanoparticles supported on metal oxides were used to catalyze the direct oxidative esterification of alcs.; esters were obtained using mol. oxygen as an oxidant under ambient temp. and pressure. Higher activities for the reaction between the benzyl alc. and methanol were obtained over Au/CeO2 and Au/ZrO2 than Au/TiO2 (anatase), Au/HT (hydrotalcite) and Au/Al2O3. These catalysts were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), at. absorption spectroscopy (AAS) and XPS. The distribution of gold nanoparticles was uniform; no change of chem. states occurred for supports and gold nanoparticles after the catalysts were reused 10 times. The oxidative esterification of various alcs. over these catalysts could also occur under optimized reaction conditions. The substituted benzyl alcs. and cinnamyl alcs. were more active than heterocyclic alcs. and aliph. alcs. because their α-H could be eliminated more easily during the induction of adsorbed dioxygen. Self-oxidative esterification was available for benzyl alc. in inert solvents with low polarity indexes. A reaction mechanism was proposed for the synthesis of esters from alcs. with mol. oxygen.(f) Verma, S.; Verma, D.; Sinha, A. K.; Jain, S. L. Palladium complex immobilized on graphene oxide–magnetic nanoparticle composites for ester synthesis by aerobic oxidative esterification of alcohols. Appl. Catal., A 2015, 489, 17, DOI: 10.1016/j.apcata.2014.10.004There is no corresponding record for this reference.(g) Wang, L.; Li, J.; Dai, W.; Lv, Y.; Zhang, Y.; Gao, S. Facile and efficient gold-catalyzed aerobic oxidative esterification of activated alcohols. Green Chem. 2014, 16, 2164, DOI: 10.1039/c3gc42075b7ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXks1yrtb8%253D&md5=cfec2837e04921b91de106a1f37bc18dFacile and efficient gold-catalyzed aerobic oxidative esterification of activated alcoholsWang, Lianyue; Li, Jun; Dai, Wen; Lv, Ying; Zhang, Yi; Gao, ShuangGreen Chemistry (2014), 16 (4), 2164-2173CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A facile and efficient methodol. is presented for the direct oxidative esterification of alcs. with alcs. catalyzed by NaAuCl4. Just in the presence of a low catalytic amt. of base additive, the newly developed catalytic system proceeds with high selectivity and broad substrate scope under mild conditions with dioxygen or air as the environmentally benign terminal oxidant. Various alcs. including benzylic and allylic alcs. were smoothly reacted with methanol and even with long-chain aliph. alcs., affording the desired products in good to excellent yields (up to 95% yield). The present system showed high catalytic activity with a TOF up to 219 h-1. Kinetic studies of the reaction process provide fundamental insights into the catalytic pathway, and a possible reaction pathway is proposed based on the results of the control expts. XPS, TEM, and UV-visible were carried out to characterize the chem. state of the Au catalyst in the present catalytic system. The Au nanoparticles were generated in situ and supported on K2CO3, forming a simple, recyclable and selective catalyst system for the direct oxidative esterification of alcs.(h) Liu, C.; Wang, J.; Meng, L.; Deng, Y.; Li, Y.; Lei, A. Palladium-Catalyzed Aerobic Oxidative Direct Esterification of Alcohols. Angew. Chem., Int. Ed. 2011, 50, 5144, DOI: 10.1002/anie.2010080737hhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtFymurk%253D&md5=f300bdd1946d99125ae8f148d59285cbPalladium-catalyzed aerobic oxidative direct esterification of alcoholsLiu, Chao; Wang, Jing; Meng, Lingkui; Deng, Yi; Li, Yao; Lei, AiwenAngewandte Chemie, International Edition (2011), 50 (22), 5144-5148CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)The first palladium-catalyzed direct aerobic oxidative esterification of benzylic alcs. with methanol and various long-chain aliph. alcs. have successfully developed. By considering the effect of substitution and potential mechanistic pathways, the authors have been able to show the applicability of this method to range of different substrates eo give their corresponding esters in moderate to high yields. The challenging esterification reaction of long-chain aliph. alcs. were accomplished by using a P-olefin ligand to control the selectivity. The direct nature of this route and the use of O2 as the oxidant represent a step toward an environmentally benign and sustainable process. Studies into the mechanistic pathway and the improvement of the reaction efficiency are currently underway.
For Cu-catalyzed aerobic oxidative esterification of ethylene glycol with primary or secondary alcohols to a mixture of oxalic acid diesters and byproducts (aldehydes/ketones and homoesterification products), see:
(i) Morino, Y.; Yatabe, T.; Suzuki, K.; Yamaguchi, K. Cu/N-Oxyl-catalyzed aerobic oxidative esterification to oxalic acid diesters from ethylene glycol via highly selective intermolecular alcohol oxidation. Green Chem. 2022, 24, 2017, DOI: 10.1039/D1GC04001DThere is no corresponding record for this reference. - 8(a) Oliveira, R. L.; Kiyohara, P. K.; Rossi, L. M. Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticles. Green Chem. 2009, 11, 1366, DOI: 10.1039/b902499a8ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVOmtbjO&md5=96af90aefb67ab4153a4f00bc328ece5Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticlesOliveira, Rafael L.; Kiyohara, Pedro K.; Rossi, Liane M.Green Chemistry (2009), 11 (9), 1366-1370CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Me esters were prepd. by the clean, 1-step catalytic esterification of primary alcs. using O2 as a green oxidant and a newly developed SiO2-supported Au nanoparticle catalyst. The catalyst was highly active and selective in a broad range of pressure and temp. At 3 atm O2 and 130°, PhCH2OH was converted to PhCO2Me with 100% conversion and 100% selectivity within 4 h. This catalytic process is much "greener" than the conventional routes, because it avoids the use of stoichiometric environmentally unfriendly oxidants, usually required for alc. oxidn., and the use of strong acids or excess of reactants or const. removal of products required to shift the equil. to the desired esterification product.(b) Nielsen, I. S.; Taarning, E.; Egeblad, K.; Madsen, R.; Christensen, C. H. Direct aerobic oxidation of primary alcohols to methyl esters catalyzed by a heterogeneous gold catalyst. Catal. Lett. 2007, 116, 35, DOI: 10.1007/s10562-007-9086-98bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXntFOqtbY%253D&md5=8b51e29d995ec2cb499e590a38a563a1Direct aerobic oxidation of primary alcohols to methyl esters catalyzed by a heterogeneous gold catalystNielsen, Inger S.; Taarning, Esben; Egeblad, Kresten; Madsen, Robert; Christensen, Claus H.Catalysis Letters (2007), 116 (1-2), 35-40CODEN: CALEER; ISSN:1011-372X. (Springer)Me esters can be produced in high yields by oxidizing methanolic solns. of primary alcs. with dioxygen over a heterogeneous gold catalyst (Au/TiO2). The versatility of this new methodol. is demonstrated by the fact that alkylic, benzylic, and allylic alcs., as well as alcs. contg. an amine functionality are oxidized in good to excellent yields.
- 9Liu, M.; Zhang, Z.; Liu, H.; Xie, Z.; Mei, Q.; Han, B. Transformation of alcohols to esters promoted by hydrogen bonds using oxygen as the oxidant under metal-free conditions. Sci. Adv. 2018, 4, eaas9319 DOI: 10.1126/sciadv.aas9319There is no corresponding record for this reference.
- 10(a) Liu, G.; Li, G.; Song, H. Direct Synthesis of Methyl Propionate from n-Propyl Alcohol and Methanol Using Gold Catalysts. Catal. Lett. 2009, 128, 493, DOI: 10.1007/s10562-008-9782-010ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVCgtLjM&md5=bcd84a112d0eacd65b2f1c580adea995Direct Synthesis of Methyl Propionate from n-Propyl Alcohol and Methanol Using Gold CatalystsLiu, Guangliang; Li, Gang; Song, HaiyanCatalysis Letters (2009), 128 (3-4), 493-501CODEN: CALEER; ISSN:1011-372X. (Springer)Me propionate was prepd. by aerobic oxidn. of PrOH dissolved in MeOH using Au/TiO2 nanocatalysts prepd. by a deposition-pptn. method. Under optimum conditions, the PrOH conversion and product selectivity reached 63% and 99%, resp. The catalyst was stable and could be recovered and reused without significant deactivation.(b) Su, F.-Z.; Ni, J.; Sun, H.; Cao, Y.; He, H.-Y.; Fan, K.-N. Gold Supported on Nanocrystalline β-Ga2O3 as a Versatile Bifunctional Catalyst for Facile Oxidative Transformation of Alcohols, Aldehydes, and Acetals into Esters. Chem.─Eur. J. 2008, 14, 7131, DOI: 10.1002/chem.20080098210bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVGrs7rE&md5=19da49575f24c7d3eca9f361d27489e4Gold supported on nanocrystalline β-Ga2O3 as a versatile bifunctional catalyst for facile oxidative transformation of alcohols, aldehydes, and acetals into estersSu, Fang-Zheng; Ni, Ji; Sun, Hao; Cao, Yong; He, He-Yong; Fan, Kang-NianChemistry - A European Journal (2008), 14 (24), 7131-7135CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Deposition of gold nanoparticles onto nanocryst. β-Ga2O3 results in the formation of a solid bifunctional catalyst that can allow facile, additive-free, aerobic oxidn. of primary alcs., aldehydes, and acetals into their resp. esters in good-to-excellent yields, providing an environmentally benign approach for the direct synthesis of carboxylic esters.(c) Caporaso, M.; Cravotto, G.; Georgakopoulos, S.; Heropoulos, G.; Martina, K.; Tagliapietra, S. Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol. Beilstein J. Org. Chem. 2014, 10, 1454, DOI: 10.3762/bjoc.10.14910chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFSqs7vL&md5=cfa71bd4b52176c69a1fbba7c7548c31Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocolCaporaso, Marina; Cravotto, Giancarlo; Georgakopoulos, Spyros; Heropoulos, George; Martina, Katia; Tagliapietra, SilviaBeilstein Journal of Organic Chemistry (2014), 10 (), 1454-1461, 8 pp.CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)An environmentally friendly microwave-assisted oxidative esterification of alcs. and aldehydes in the presence of mol. oxygen and a heterogeneous catalysis (Pd/C, 5 mol %) is described. This efficient and ligandless conversion procedure does not require the addn. of an org. hydrogen acceptor. The reaction rate is strongly enhanced by mild dielec. heating. Furthermore, it is a versatile green procedure which generally enables the isolation of esters I (R1 = Ph, 4-MeOC6H4, 4-N2OC6H4, etc.; R2 = Me, Et, n-Pr, etc.) to be carried out by simple filtration in almost quant. yields.
- 11Martínez, S.; Veth, L.; Lainer, B.; Dydio, P. Challenges and opportunities in multicatalysis. ACS Catal. 2021, 11, 3891, DOI: 10.1021/acscatal.0c0572511https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmtlSktr0%253D&md5=3bbf88e033ec62c77d8306e41b279154Challenges and Opportunities in Multi-CatalysisMartinez, Sebastian; Veth, Lukas; Lainer, Bruno; Dydio, PawelACS Catalysis (2021), 11 (7), 3891-3915CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. Multicatalysis is an emerging field targeting the development of efficient catalytic transformations to quickly convert relatively simple starting materials into more complex value-added products. Within multicatalytic processes either multiple catalysts execute single reactions or precise sequences of multiple catalytic reactions occur in a "one-pot" fashion. Attractively, multicatalytic protocols not only enable transformations that are inaccessible through classic approaches, but also are able to significantly reduce time, waste, and cost of the synthetic processes, making org. synthesis more resources efficient. In this Perspective article, different strategies in multicatalysis that bring distinct challenges and opportunities has been reviewed. The overarching field is divided into three main categories: cooperative, domino, and relay catalysis. Each category is described along with representative examples to highlight its features. Special emphasis is dedicated to relay catalysis, which is further discussed in its subcategories. Lastly, an anal. of systems that incorporate higher levels of complexity and further underscore the potential of multicatalytic systems has been discussed.
- 12(a) Ma, S.; Liu, J.; Li, S.; Chen, B.; Cheng, J.; Kuang, J.; Liu, Y.; Wan, B.; Wang, Y.; Ye, J.; Yu, Q.; Yuan, W.; Yu, S. Development of a General and Practical Iron Nitrate/TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones: Catalysis with Table Salt. Adv. Synth. Catal. 2011, 353, 1005, DOI: 10.1002/adsc.20110003312ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXltVGmt78%253D&md5=65c3939a61295b53b943b8656616eac3Development of a General and Practical Iron Nitrate/TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones: Catalysis with Table SaltMa, Sheng-Ming; Liu, Jin-Xian; Li, Su-Hua; Chen, Bo; Cheng, Jia-Jia; Kuang, Jin-Qiang; Liu, Yu; Wan, Bao-Qiang; Wang, Yu-Li; Ye, Jun-Tao; Yu, Qiong; Yuan, Wei-Ming; Yu, Shi-ChaoAdvanced Synthesis & Catalysis (2011), 353 (6), 1005-1017CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)Oxidn. of alcs. is a fundamental transformation related to our daily life. Traditional approaches with at least one stoichiometric amt. of oxidants are expensive and cause serious environmental burdens. There are many reports on the aerobic oxidn. of simple alcs. such as alkyl or Ph carbinols and allylic alcs., which used oxygen or air as the environmentally benign oxidant forming water as the only byproduct. However, no such protocol has been reported for allenols and propargylic alcs. Thus, it still highly desirable to develop efficient room temp. oxidns. of alcs. with a wide scope including allenols and propargylic alcs. In this paper, an efficient and clean aerobic oxidn. of so far the widest spectrum of alcs. using 1 atm of oxygen or air, producing aldehydes/ketones at room temp. in fairly high isolated yields mostly within a couple of hours is described. It is interesting to observe that the reaction has been efficiently expedited by a catalytic amt. of sodium chloride in easily recoverable 1,2-dichloroethane. A mechanism involving NO and NO2 has been proposed based on the results of the control expts. and GC-MS studies of the in-situ formed gas phase of the reaction mixt.(b) Wang, L.; Shang, S.; Li, G.; Ren, L.; Lv, Y.; Gao, S. Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere. J. Org. Chem. 2016, 81, 2189, DOI: 10.1021/acs.joc.6b0000912bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitlCjtr8%253D&md5=a276aa778ca304c5901bff1e5574c6d5Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient AtmosphereWang, Lianyue; Shang, SenSen; Li, Guosong; Ren, Lanhui; Lv, Ying; Gao, ShuangJournal of Organic Chemistry (2016), 81 (5), 2189-2193CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)We report a new Fe(NO3)3·9H2O/9-azabicyclo[3.3.1]nonan-N-oxyl catalyst system that enables efficient aerobic oxidn. of a broad range of primary and secondary alcs. to the corresponding aldehydes and ketones at room temp. with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliph. alc. oxidn. This procedure can also be scaled up. Kinetic anal. demonstrates that C-H bond cleavage is the rate-detg. step and that cationic species are involved in the reaction.(c) Hong, M.; Min, J.; Wu, S.; Cui, H.; Zhao, Y.; Li, J.; Wang, S. Metal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen Atmosphere. ACS Omega 2019, 4, 7054, DOI: 10.1021/acsomega.9b0039112chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnsFGrtb0%253D&md5=c174245864aacf84a6df4e3fedd7c8cbMetal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen AtmosphereHong, Mei; Min, Jie; Wu, Shuangyan; Cui, Huangui; Zhao, Yuxin; Li, Jiatong; Wang, ShifaACS Omega (2019), 4 (4), 7054-7060CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)Selective synthesis of various versatile compds. from biomass is of great importance to displace traditional fossil fuel resources. Here, homogeneous metal nitrate/TEMPO and metal nitrate/TEMPO/NaNO2 catalyst systems in glacial acetic acid and acetonitrile, resp., have been found highly active and practical sustainable selective oxidn. 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) using pure O2 or even O2 in air as the oxidant. The catalytic methods enable full HMF conversion with a nearly 100% DFF selectivity at 50°C under atm. pressure using a very simple reaction setup and workup. Mechanistic aspects are discussed. The influences of reaction conditions such as different metal catalysts, catalyst loading, solvents and reaction temp. on the promotion effect were studied. Meanwhile, the catalyst systems had also good performance for aerobic oxidn. of other alcs.(d) Jiang, X.; Zhang, J.; Ma, S. Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic Acids. J. Am. Chem. Soc. 2016, 138, 8344, DOI: 10.1021/jacs.6b0394812dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XpvFynt7o%253D&md5=639bfbe022d9bdf9137c221aaaa9bc02Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic AcidsJiang, Xingguo; Zhang, Jiasheng; Ma, ShengmingJournal of the American Chemical Society (2016), 138 (27), 8344-8347CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Oxidn. from alcs. to carboxylic acids, a class of essential chems. in daily life, academic labs., and industry, is a fundamental reaction, usually using at least a stoichiometric amt. of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidn. technol. of alcs. to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amt. each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcs. (also aldehydes) in high yields at room temp. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished.(e) Nutting, J. E.; Mao, K.; Stahl, S. S. Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity. J. Am. Chem. Soc. 2021, 143, 10565, DOI: 10.1021/jacs.1c0522412ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1Wms7fK&md5=2bcfa2ede35251963e96071f7d513426Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox CooperativityNutting, Jordan E.; Mao, Kaining; Stahl, Shannon S.Journal of the American Chemical Society (2021), 143 (28), 10565-10570CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Aerobic alc. oxidns. catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which CuII and the aminoxyl participate together to mediate alc. oxidn. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alc. is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixt. by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NOx-based redox cycle for oxidn. of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alc. oxidn. chemoselectivity and functional group compatibility.(f) Li, J.; Liu, J.; Fu, C.; Ma, S. Fe(III)-Catalyzed Aerobic Oxidation of 1,4-Diols. Chin. J. Chem. 2023, 41, 1963, DOI: 10.1002/cjoc.202200768There is no corresponding record for this reference.
- 13
For reports on aerobic oxidative cross-esterification of activated benzylic alcohols and cinnamyl alcohols with noble-metal catalysts, see:
(a) Miyamura, H.; Yasukawa, T.; Kobayashi, S. Aerobic oxidative esterification of alcohols catalyzed by polymer-incarcerated gold nanoclusters under ambient conditions. Green Chem. 2010, 12, 776, DOI: 10.1039/b926877d13ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXlvVGhs7Y%253D&md5=ce5714b5b9c55221af2dd91e4b5ebb68Aerobic oxidative esterification of alcohols catalyzed by polymer-incarcerated gold nanoclusters under ambient conditionsMiyamura, Hiroyuki; Yasukawa, Tomohiro; Kobayashi, ShuGreen Chemistry (2010), 12 (5), 776-778CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Environmentally benign aerobic oxidn. of alcs. to Me esters catalyzed by polymer-immobilized gold nanoclusters (PI-Au) was developed and reactions proceeded under very mild conditions. The catalyst could be recovered by simple operations without significant loss of activity.(b) Chng, L. L.; Yang, J.; Ying, J. Y. Efficient Synthesis of Amides and Esters from Alcohols under Aerobic Ambient Conditions Catalyzed by a Au/Mesoporous Al2O3 Nanocatalyst. ChemSusChem 2015, 8, 1916, DOI: 10.1002/cssc.20140346913bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnsFClsLg%253D&md5=f452f4f14f71ede01d54aee19f1c884cEfficient synthesis of amides and esters from alcohols under aerobic ambient conditions catalyzed by a Au/mesoporous Al2O3 nanocatalystChng, Leng Leng; Yang, Jinhua; Ying, Jackie Y.ChemSusChem (2015), 8 (11), 1916-1925CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)An efficient heterogeneous mesoporous-alumina-supported gold nanocatalyst was successfully developed for the synthesis of amides e.g.,I and esters via direct amidation of benzyl alcs. with amines and oxidative esterification of alcs. with methanol resp. This protocol had the advantages of simple reaction and high isolated yield under aerobic ambient conditions. Furthermore, the nanocatalyst was stable to air and water and could be recovered and reused easily. The ability of mesoporous-alumina gold nanoparticles to catalyze these reactions under ambient conditions further enhances the sustainability of these chem. processes. The enhanced catalytic activity of Au/mesoporous alumina might be attributed to the presence of neg. charged Au nanoparticles that could promote oxidn. processes as well as the stability of the mesoporous alumina support calcined at a high temp. of 800 °C.(c) Xiao, Q.; Liu, Z.; Bo, A.; Zavahir, S.; Sarina, S.; Bottle, S.; Riches, J. D.; Zhu, H. Catalytic Transformation of Aliphatic Alcohols to Corresponding Esters in O2 under Neutral Conditions Using Visible-Light Irradiation. J. Am. Chem. Soc. 2015, 137, 1956, DOI: 10.1021/ja511619c13chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlyks78%253D&md5=68cafade06c11313c5b61f2b07bfab38Catalytic Transformation of Aliphatic Alcohols to Corresponding Esters in O2 under Neutral Conditions Using Visible-Light IrradiationXiao, Qi; Liu, Zhe; Bo, Arixin; Zavahir, Sifani; Sarina, Sarina; Bottle, Steven; Riches, James D.; Zhu, HuaiyongJournal of the American Chemical Society (2015), 137 (5), 1956-1966CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Selective oxidn. of aliph. alcs. under mild and base-free conditions is a challenging process for org. synthesis. Herein, we report a one-pot process for the direct oxidative esterification of aliph. alcs. that is significantly enhanced by visible-light irradn. at ambient temps. The new methodol. uses heterogenerous photocatalysts of gold-palladium alloy nanoparticles on a phosphate-modified hydrotalcite support and mol. oxygen as a benign oxidant. The alloy photocatalysts can absorb incident light, and the light-excited metal electrons on the surface of metal nanoparticles can activate the adsorbed reactant mols. Tuning the light intensity and wavelength of the irradn. can remarkably change the reaction activity. Shorter wavelength light (<550 nm) drives the reaction more efficiently than light of longer wavelength (e.g., 620 nm), esp. at low temps. The phosphate-exchanged hydrotalcite support provides sufficient basicity (and buffer) for the catalytic reactions; thus, the addn. of base is not required. The photocatalysts are efficient and readily recyclable. The findings reveal the first example of using "green" oxidants and light energy to drive direct oxidative esterification of aliph. alcs. under base-free, mild conditions.(d) Mondal, P.; Salam, N.; Mondal, A.; Ghosh, K.; Tuhina, K.; Islam, S. M. A highly active recyclable gold–graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathway. J. Colloid Interface Sci. 2015, 459, 97, DOI: 10.1016/j.jcis.2015.07.07213dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlSksrzL&md5=6a3b007b9b475760579164502bac4a82A highly active recyclable gold-graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathwayMondal, Paramita; Salam, Noor; Mondal, Avijit; Ghosh, Kajari; Tuhina, K.; Islam, Sk. ManirulJournal of Colloid and Interface Science (2015), 459 (), 97-106CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)A graphene based composite with gold nanoparticles has been synthesized via a simple chem. route and the structure and compns. of nanocomposite has been characterized. The catalyst was found to be remarkably stable and active for the oxidative esterification of alcs. under present reaction conditions using mol. oxygen as green oxidant and Suzuki cross-coupling reactions between aryl halides and phenylboronic acids using environmentally friendly water as solvent. The versatility of both the protocols was demonstrated by taking a no. of substrates. This protocol offers several advantages like high yields, clean reactions, recyclability of the catalyst, reaction in water and use of green oxidant. This study suggests graphene, as an economical substitute for carbon nanotubes, could act as a prominent support in heterogeneous catalysis.(e) Tsai, C.-H.; Xu, M.; Kunal, P.; Trewyn, B. G. Aerobic oxidative esterification of primary alcohols over Pd-Au bimetallic catalysts supported on mesoporous silica nanoparticles. Catal. Today 2018, 306, 81, DOI: 10.1016/j.cattod.2017.01.04613ehttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXisVejsLw%253D&md5=9516b8e7e2c7433299dd37d57ef2a494Aerobic oxidative esterification of primary alcohols over Pd-Au bimetallic catalysts supported on mesoporous silica nanoparticlesTsai, Chih-Hsiang; Xu, Mengze; Kunal, Pranaw; Trewyn, Brian G.Catalysis Today (2018), 306 (), 81-88CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)We have prepd. a series of mesoporous silica nanoparticle (MSN) supported Pd-Au bimetallic catalysts using a newly developed sequential impregnation method. These catalysts were fully characterized by various techniques including nitrogen sorption, powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and high angle annular dark-field scanning transmission electron microscopy (HADDF-STEM). By using this synthetic approach, we obsd. metal nanoparticles (NP) with diams. of 1-2 nm homogeneously supported on the MSN. The catalytic performance of these MSN supported metal NPs was tested by aerobic oxidative esterification in a tandem reaction where primary alcs. are oxidized to their corresponding aldehydes and to esters in a subsequent reaction. We detd. that Pd NPs are very efficient in the first step of oxidn.; however, stagnant in the subsequent oxidn. On the contrary, Au NPs show slow reactivity in converting alcs. to aldehydes, but extraordinarily efficient in the oxidn. of aldehydes to esters. By fine tuning the metal ratio, the bimetallic catalyst exhibits better reactivity and selectivity toward a variety of primary alcs. than the corresponding monometallic catalysts. In addn., we also found that the bimetallic Pd-Au@MSN catalysts can be recycled three times without a significant loss in activity.(f) Li, F.; Li, X.-L.; Li, C.; Shi, J.; Fu, Y. Aerobic oxidative esterification of 5-hydroxymethylfurfural to dimethyl furan-2,5-dicarboxylate by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygen. Green Chem. 2018, 20, 3050, DOI: 10.1039/C8GC01393D13fhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtV2gurnI&md5=5b2b411a955cf941ca9e3f0f5d29e055Aerobic oxidative esterification of 5-hydroxymethylfurfural to dimethyl furan-2,5-dicarboxylate by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygenLi, Feng; Li, Xing-Long; Li, Chuang; Shi, Jing; Fu, YaoGreen Chemistry (2018), 20 (13), 3050-3058CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)The conversion of platform mol. 5-hydroxymethylfurfural (HMF) into many value-added derivs. has attracted significant interest. FDCA and its esters are important derivs. of HMF, which can be used as polyester monomers and pharmaceutical intermediates. In this paper, oxidative esterification of 5-HMF has been carried out by using homogeneous and heterogeneous PdCoBi/C catalysts under atm. oxygen. The effect of reaction conditions on product distribution has been studied under both homogeneous and heterogeneous catalytic conditions. The highest yields of oxidative esterification products are obtained at 93% and 96% by using homogeneous and heterogeneous PdCoBi/C catalysts, resp. The catalysts are characterized by XPS and powder X-ray diffraction (XRD). The catalytic system has better compatibility according to the expansion of the substrate. A reaction mechanism is proposed, and recycle expts. are also conducted.(g) Salam, N.; Banerjee, B.; Roy, A. S.; Mondal, P.; Roy, S.; Bhaumik, A.; Islam, S. M. Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcohols. Appl. Catal., A 2014, 477, 184, DOI: 10.1016/j.apcata.2014.03.01413ghttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmslKhs74%253D&md5=70a3680cb2fb00a3b03380e7886753f4Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcoholsSalam, Noor; Banerjee, Biplab; Roy, Anupam Singha; Mondal, Paramita; Roy, Susmita; Bhaumik, Asim; Islam, Sk. ManirulApplied Catalysis, A: General (2014), 477 (), 184-194CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Silver nanoparticles (Ag-NPs) have been finely dispersed at the mesoporous org. polymer via post-synthetic chem. grafting over mesoporous poly-triallylamine (MPTA-1). The resulting Ag-MPTA-1 nanomaterial has been characterized by elemental anal., powder x-ray diffraction (x-ray diffraction), TEM, Fourier transform IR spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), thermogravimetric anal. (TGA), EPR spectroscopy and AAS elemental anal. The Ag-MPTA-1 acts as an efficient heterogeneous nanocatalyst in the redn. of substituted nitrobenzenes via transfer hydrogenation. The material also showed excellent catalytic activity in one-step catalytic oxidative esterification of primary alcs. using mol. oxygen as a green oxidant. The catalyst is air-stable, inexpensive, easy to prep. and reused several times without significant decrease in activity and selectivity.(h) Gowrisankar, S.; Neumann, H.; Beller, M. General and Selective Palladium-Catalyzed Oxidative Esterification of Alcohols. Angew. Chem., Int. Ed. 2011, 50, 5139, DOI: 10.1002/anie.20100803513hhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtFymtLg%253D&md5=798061c7944dc7f22ce3ae3c391a6474General and Selective Palladium-Catalyzed Oxidative Esterification of AlcoholsGowrisankar, Saravanan; Neumann, Helfried; Beller, MatthiasAngewandte Chemie, International Edition (2011), 50 (22), 5139-5143CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)New palladium-catalyzed oxidative esterification reactions of primary benzylic alcs. with dioxygen as benign oxidant is described. E.g., in presence of Pd(OAc)2 and the ligand cataCXiumA, oxidative esterification of BnOH with 1-pentanol gave 88% pentyl benzoate. Both oxidative homocoupling reactions as well as cross-esterifications of benzyl alcs. with various aliph. alcs. proceed under mild conditions (50-100°C, 1 bar oxygen) to give the corresponding esters with water as the only side-product.(i) Luo, F.; Pan, C.; Cheng, J.; Chen, F. Palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols. Tetrahedron 2011, 67, 5878, DOI: 10.1016/j.tet.2011.06.060There is no corresponding record for this reference.(j) Bai, X.-F.; Ye, F.; Zheng, L.-S.; Lai, G.-Q.; Xia, C.-G.; Xu, L.-W. Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with air. Chem. Commun. 2012, 48, 8592, DOI: 10.1039/c2cc34117d13jhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFaju7jE&md5=445a4c84050a74e83c3f91577be27845Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with airBai, Xing-Feng; Ye, Fei; Zheng, Long-Sheng; Lai, Guo-Qiao; Xia, Chun-Gu; Xu, Li-WenChemical Communications (Cambridge, United Kingdom) (2012), 48 (68), 8592-8594CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)In a palladium-catalyzed oxidative esterification, hydrosilane can serve as an activator of palladium catalyst with bismuth, thus leading to a novel ligand- and silver-free palladium catalyst system for facile oxidative esterification of a variety of benzylic alcs. in good yields.(k) Hu, Y.; Li, B. Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions. Tetrahedron 2017, 73, 7301, DOI: 10.1016/j.tet.2017.11.025There is no corresponding record for this reference. - 14
For the reports on Pd-catalyzed aerobic oxidative cross-esterification with the promotion of bases, see:
Powell, A. B.; Stahl, S. S. Aerobic Oxidation of Diverse Primary Alcohols to Methyl Esters with a Readily Accessible Heterogeneous Pd/Bi/Te Catalyst. Org. Lett. 2013, 15, 5072, DOI: 10.1021/ol402428e14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVygu7fP&md5=52d3ff7d8ff29f45324ed26bfadc4a74Aerobic Oxidation of Diverse Primary Alcohols to Methyl Esters with a Readily Accessible Heterogeneous Pd/Bi/Te CatalystPowell, Adam B.; Stahl, Shannon S.Organic Letters (2013), 15 (19), 5072-5075CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)Efficient aerobic oxidative Me esterification of primary alcs. has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate scope and is effective with both activated (benzylic) and unactivated (aliph.) alcs. bearing diverse functional groups. Safety: fire hazard in addn. of neutral MeOH to Pd/charcoal. - 15(a) Huang, X.; Ma, S. Allenation of terminal alkynes with aldehydes and ketones. Acc. Chem. Res. 2019, 52, 1301, DOI: 10.1021/acs.accounts.9b0002315ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnt1Ght7g%253D&md5=2419c15230a0c423f0fef1758a3aa26eAllenation of Terminal Alkynes with Aldehydes and KetonesHuang, Xin; Ma, ShengmingAccounts of Chemical Research (2019), 52 (5), 1301-1312CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. So far, over 150 natural products and pharmaceuticals contg. an allene moiety have been identified. During the last two decades, allenes have also been demonstrated as synthetically versatile starting materials in org. synthesis. In comparison to alkenes and alkynes, allenes are unique unsatd. hydrocarbons due to their axial chirality, which could be transformed to central chirality via chirality transfer to provide an irreplaceable entry to chiral mols. Thus, methods for allene synthesis from readily available chems. are of great interest. In 1979, Crabb´e et al. reported the first CuBr-mediated allenation of terminal alkynes (ATA reaction) to form monosubstituted allenes from 1-alkynes and paraformaldehyde in the presence of diisopropylamine. During the following 30 years, the ATA reactions were limited to paraformaldehyde. This Account describes our efforts toward the development of ATA reactions in the last ten years. First, we improved the yields and scope greatly for the synthesis of monosubstituted allenes by modifying the original Crabb´e recipe. Next we developed the ZnI2-promoted or CuI-catalyzed ATA reactions for the synthesis of 1,3-disubstituted allenes from terminal alkyne and normal aldehydes. Furthermore, we first realized the CdI2-promoted ATA reaction of ketones with pyrrolidine as the matched amine for the prepn. of trisubstituted allenes. Due to the toxicity of CdI2, we also developed two alternative approaches utilizing CuBr/ZnI2 or CuI/ZnBr2/Ti(OEt)4. The asym. version of ATA reactions for the synthesis of optically active 1,3-disubstituted allenes has also been achieved in this group with two strategies. One is called "chiral ligand" strategy, using terminal alkynes, aldehydes, and nonchiral amine with the assistance of a proper chiral ligand. The other is the "chiral amine" strategy, applying terminal alkynes, aldehydes, and chiral amines such as (S)- or (R)-α,α-diphenylprolinol or (S)- or (R)-α,α-dimethylprolinol. Optically active 1,3-disubstituted allenes contg. different synthetically useful functionalities such as alc., amide, sulfamide, malonate, carboxylate, and carbohydrate units could be prepd. without protection with the newly developed CuBr2-catalyzed chiral amine strategy. Recently, we have applied these enantioselective allenation of terminal alkyne (EATA) reactions to the syntheses of some natural allenes such as laballenic acid, insect pheromone, Me (R)-8-hydroxyocta-5,6-dienoate, phlomic acid, and lamenallenic acid, as well as some non-allene natural γ-butyrolactones such as xestospongienes (E, F, G, and H), (R)-4-tetradecalactone, (S)-4-tetradecalactone, (R)-γ-palmitolactone, and (R)-4-decalactone.(b) Huang, X.; Cao, T.; Han, Y.; Jiang, X.; Lin, W.; Zhang, J.; Ma, S. General CuBr2-catalyzed highly enantioselective approach for optically active allenols from terminal alkynols. Chem. Commun. 2015, 51, 6956, DOI: 10.1039/C5CC00697J15bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXkt1Ogu78%253D&md5=bd18b9f37a3e6e53c59e22b5595402e9General CuBr2-catalyzed highly enantioselective approach for optically active allenols from terminal alkynolsHuang, Xin; Cao, Tao; Han, Yulin; Jiang, Xingguo; Lin, Weilong; Zhang, Jiasheng; Ma, ShengmingChemical Communications (Cambridge, United Kingdom) (2015), 51 (32), 6956-6959CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)It was reported that a CuBr2-catalyzed approach for a highly enantioselective synthesis (93-99% ee) of allenols from aldehydes and terminal alkynols with the abs. configuration being controlled by applying readily available (R)- or (S)-α,α-diphenylprolinol.(c) Tang, X.; Huang, X.; Cao, T.; Han, Y.; Jiang, X.; Lin, W.; Tang, Y.; Zhang, J.; Yu, Q.; Fu, C.; Ma, S. CuBr2-catalyzed enantioselective routes to highly functionalized and naturally occurring allenes. Org. Chem. Front. 2015, 2, 688, DOI: 10.1039/C5QO00084J15chttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmt1WqtrY%253D&md5=a292c6014497d91ebacf51139c17d95aCuBr2-catalyzed enantioselective routes to highly functionalized and naturally occurring allenesTang, Xinjun; Huang, Xin; Cao, Tao; Han, Yulin; Jiang, Xingguo; Lin, Weilong; Tang, Yang; Zhang, Jiasheng; Yu, Qiong; Fu, Chunling; Ma, ShengmingOrganic Chemistry Frontiers (2015), 2 (6), 688-691CODEN: OCFRA8; ISSN:2052-4129. (Royal Society of Chemistry)The CuBr2-catalyzed approach for highly enantioselective synthesis (90-98% ee) of allenes bearing a very broad array of unmasked synthetically attractive functionalities from aldehydes and terminal alkynyl bearing reactive functionalities with the abs. configuration controlled by applying readily available (R)- or (S)-α,α-diphenylprolinol is described. Following this protocol, the highly enantioselective synthesis of some naturally occurring allenes loaded with reactive functionalities becomes simple: a terminal alkyne plus an aldehyde. In comparison, they were reported to be synthesized either from similar level generic chems. with much more steps or in lower ees.
- 16Aitzetmüller, K.; Tsevegsüren, N.; Vosmann, K. A New Allenic Fatty Acid in Phlomis (Lamiaceae) Seed Oil. Lipid/Fett 1997, 99, 74, DOI: 10.1002/lipi.19970990304There is no corresponding record for this reference.
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