过渡金属催化醇氧化反应的研究进展

氧化醇为相应的羰基化合物在有机化学基础研究及其工业应用中占有非常重要的地位.在众多关于醇氧化反应的研究中,如何使用对环境友好的氧化剂替代传统的氧化剂,选择具有高性能、廉价、清洁、可回收的催化剂,一直是化学工作者研究的一个热点.综述了近年来该研究领域中的一些重要过渡金属催化体系,并简要介绍了各类催化氧化体系的催化效果.     

可见光驱动表面富含氧空位Nb2O5催化醇氧化反应

醇氧化合成相应的羰基化合物在有机化学基础研究及工业应用中占有非常重要的地位.通过表面富含氧空位Nb₂O₅光催化剂的开发,发展了一种醇氧化为羰基化合物的绿色高效合成方法.该催化体系具有反应条件温和,底物适用性强和官能团兼容性广的特点.此外,该催化剂表现出优良的性能稳定性,循环使用多次后,保持催化活性不变.     

酶催化反应在立体有机合成中的应用

讨论了水解酶、交换酶以及氧化还原酶催化的位置、对映和潜手性立体专一的反应，包括酶催化的醇或酯的水解反应、酯交换反应、含羰基的化合物及活泼双键的还原反应、ＳＰ￣３杂化的碳及烯的氧化反应（包括Ｂａｙｅｒ－Ｖｉｌｌｉｎｇｅｒ氧化反应）。回顾了酶立体选择性地合成某些重要目标结构的生物催化方法，讨论了酶催化反应的生物合成前景。参考文献１８篇。     

氧化还原酶介导生物级联催化研究进展

氧化还原酶种类丰富,广泛应用于生物催化级联反应中。以细胞色素P450单加氧酶和羰基还原酶为例,综述了两者参与的级联催化反应及其在合成手性胺和手性醇等化合物中的应用,并对发展氧化还原酶级联催化反应面临的辅酶循环、限速步骤和化合物抑制等问题进行了讨论。     

环烯丙醇的四氧化锇氧化反应

四氧化锇转换烯烃为邻二醇是熟知的反应,文献也有报道链状的烯丙醇被四氧化锇氧化为相应的三醇化合物。本文报道,当环烯丙醇被四氧化锇氧化时。则随烯烃空间障碍的不同而结果不同。空间隙碍比较大的环烯丙醇得到羟基被氧化的α、β不饱和羰基化合物;空间障碍小的则主要产物为相应的三醇化合物;而具有中等程度空间障碍的环烯丙醇得到二类竞争性反应产物,即相应的三醇化合物和α、β不饱和羰基化合物。     

乙酸镍吡啶配合物催化的分子氧氧化反应研究

Ni(OAc)2结合吡啶和叔丁基过氧化氢(TBHP)实现了苄基C-H与苄基醇类化合物在温和条件下(80～90℃,O21 atm)的选择性催化分子氧氧化反应.研究了过氧化物添加剂,配体,溶剂和温度的影响,得到了优化的反应条件.在苄基C-H的氧化中显示了很高的酮/醇选择性.用ESR法进行了Ni(III)的检测,证实了反应机理.竞争实验说明羰基化合物的生成不是因为醇继续氧化.酮可被解释为过氧化氢中间体受金属催化分解的产物.     

过渡金属配合物催化炔烃和亲核试剂的羰化反应

羰化反应(氢甲酰化反应、羰化羧酸化反应、羰化酯化反应、羰化酰胺化反应等)是制备醛(/醇)、羧酸、羧酸酯、酰胺等高附加值含氧羰基化合物有效的途径,具有反应原子经济性高、目标羰基化合物选择性高、反应条件较氧化过程更温和可控的优势。羰化反应的原料包括烯烃、炔烃、卤代烃、醇等有机化合物。其中,在过渡金属催化剂作用下,炔烃与不同的亲核试剂(水、醇、胺等)通过发生(单/双)羰化反应可以100%原子经济性地合成(不饱和/饱和)羰基化合物(如羧酸、羧酸酯、酰胺),制得的羧酸、羧酸酯、酰胺等羰基化合物不仅在医药、农业、日化工业中有广泛用途,还是聚合、Aldol 缩合和Micheal加成等有机反应中过程反应的重要原料。因此,过渡金属催化的炔烃羰化反应成为均相催化领域受到广泛关注的研究内容。本文从不同类型的炔烃羰化反应和反应中所用羰源等方面综述了近十年来该领域的研究现状并展望其发展前景。     

相转移催化下二醇类及肟类的选择性间接电氧化

在对Cr(VI)/Cr(III)体系在相转移催化下对醇类的选择性间接电氧化进行了探讨,发现共醇类能被高产率、选择性地氧化为相应的羰基化合物,而非苄醇类则无此效果的基础上,本文是在此基础上,对分子内含有苄醇羟基和另一个非苄醇羟基的二醇类及肟类化合物进行了选择性电氧化的探讨,结果发现,在本实验条件下,共醇羟基能被选择性地氧化为相应的羰基,而分子内共存的非苄醇羟基几乎不受影响;各种肟类化合物也能有选择地氧化裂解为相应的羰基化合物,而不被深度氧化。     

米格列醇的合成

以2,3,4,6-O-四苄基-D-葡萄糖为原料,经还原,Swern氧化,双还原胺化,催化氢解脱苄基得米格列醇,四步反应总收率为50%。该过程首次用乙醇胺直接与四苄基葡萄糖二羰基衍生物进行双还原胺化反应合成了米格列醇,是一条合成米格列醇的新路线。所得化合物的结构通过1H-NMR,13C-NMR和MS进行确证。     

氟化钾催化下取代苯甲醛的硅氢化反应

硅氢化合物对羰基化合物的加成反应是合成含烷氧基硅烷的方法,其产物水解后得醇,因此该反应已作为羰基还原的新方法应用于有机合成。多种催化剂可催化该反应,常见的有:H_2PtCl_6·H_2O、PdCl_2、(Ph_3P)_3RhCl、NiCl_2等。七十年代末期,法国的 Corriu 等人发现了一种新的催化羰基化合物硅氢化的体系,即使用盐类型的氟化物     

Ruthenium-catalyzed regioselective deuteration of alcohols at the β-carbon position with deuterium oxide

A convenient method for regioselective H/D exchange between D(2)O and alcohols at the β-carbon position using the catalytic system [(p-cymene)RuCl(2)]/ethanolamine/KOH is described. This method is applicable for deuteration of both primary and secondary alcohols. The H/D exchange reactions proceed through an oxidation/modification/reduction reaction sequence. Alcohols are first temporarily oxidized to carbonyl compounds by the hydrogen transfer catalyst. The carbonyl compounds then undergo deuteration at the carbon adjacent to the carbonyl group by keto-enol tautomerization in the presence of D(2)O and a catalytic amount of base. The deuterated carbonyl compounds are then reduced to produce deuterated alcohols. In support of the reaction mechanism, a well-defined bimetallic ruthenium complex was isolated from the reaction of [{(p-cymene)RuCl(2)}(2)] with ethanolamine. The activity of this complex is similar to that of [{(p-cymene)RuCl(2)}(2)]/ethanolamine.     

Oxidation of Benzylic Alcohols to Their Corresponding Carbonyl Compounds using KIO4 in Ionic Liquid by Microwave Irradiation

A chemoselective, straightforward, and rapid method for oxidation of alcohols to the corresponding carbonyl compounds using microwave irradiation and a catalytic amount of ionic liquid is reported. The reaction has been carried out with excellent yields and short reaction times.     

Cu(II) 2-quinoxalinol salen catalyzed oxidation of propargylic,benzylic, and allylic alcohols using tert-butyl hydroperoxide in aqueous solutions

The synthesis of carbonyl compounds by oxidation of alcohols is a key reaction in organic synthesis. Such oxidations are typically conducted using catalysts featuring toxic metals and hazardous organic solvents. Considering green and sustainable chemistry, a copper(II) complex of sulfonated 2-quinoxalinol salen (sulfosalqu) has been characterized as an efficient catalyst for the selective oxidation of propargylic, benzylic, and allylic alcohols to the corresponding carbonyl compounds in water when in combination with the oxidant tert-butyl hydroperoxide. The reactions proceed under mild conditions (70 °C in water) to produce yields up to 99% with only 1 mol % of catalyst loading. This reaction constitutes of a rare example of propargylic alcohol oxidation in water, and it makes this process greener by eliminating the use of hazardous organic solvents. Excellent selectivity was achieved with this catalytic protocol for the oxidation of propargylic, benzylic, and allylic alcohols over aliphatic alcohols. The alcohol oxidation is thought to go through a radical pathway.     

An Overview of Selective Oxidation of Alcohols: Catalysts,Oxidants and Reaction Mechanisms

The oxidation of alcohols to carbonyl compounds is one of the most fundamental reactions in synthetic organic chemistry. In order to achieve the realization of dehydrogenation reactions with high atomic efficiency, suitable catalysts and oxidants are considered as the key factors to obtain the optimum activity and aldehydes/ketones selectivity. This review aims to make an overview on the reasonable reaction mechanism and promising catalytic system of alcohols dehydrogenation.     

Simple,Copper(I)-Catalyzed Oxidation of Benzylic/Allylic Alcohols to Carbonyl Compounds: Synthesis of Functionalized Cinnamates in One Pot

An environmentally benign [Cu(I)]-catalyzed oxidation of activated (benzylic/allylic) alcohols to the corresponding carbonyl compounds is presented. Interestingly, the reaction was also compatible with benzylic alcohols containing ortho-bromo substituents on the aromatic ring without competing with the expected intermolecular Buchwald coupling. Significantly, the catalytic system enables the synthesis of cinnamate-esters in a sequential domino one-pot fashion via oxidation followed by Wittig–Horner protocol.     

Aerobic oxidation of alcohol in aqueous solution catalyzed by gold

The heterogeneous oxidation catalyzed by supported gold nanoparticles has been relatively well studied. In comparison, the oxidation of alcohols catalyzed by ligand-supported gold complexes was rarely reported. Herein a general method is demonstrated to oxidize secondary and primary benzyl and allylic alcohols to carbonyl compounds via Au(I) catalyzed reaction in air and water. Primary mechanistic studies indicated that the catalytic pathway is different from those catalyzed by solid-supported gold nanoparticles.     

Cyclohexene Promoted Efficient Biomimetic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by Manganese Porphyrin under Mild Conditions

Selective oxidation of alcohols to corresponding carbonyl compounds is one of the most important processes both in academic and application research. As a kind of biomimetic catalyst, metalloporphyrins‐catalyzed aerobic oxidation of alcohols with aldehyde as hydrogen donator is gathering much attention. However, using olefins as another kind hydrogen donator for aerobic oxidation of alcohols has not been reported. In this study, a system comprising managenese porphyrin and cyclohexene for biomimetic aerobic oxidation of alcohols to carbonyl compounds was developed. The catalytic system exhibited excellent catalytic performance and selectivity towards the corresponding products for most primary and secondary alcohols under mild conditions. Based on the results obtained from experiments as well as in situ EPR (electron paramagnetic resonance) and UV‐vis spectroscopy, the role of cyclohexene was demonstrated.     

金属卟啉/MgAl水滑石催化醇选择性氧化制备羰基化合物

将MgAl水滑石引入到金属四苯基卟啉(MTPPs,M=Co,Fe,Mn,Ni)催化氧化体系中,实现了醇的选择性氧化。 结果表明,在分子氧/异丁醛体系中,CoTPP在苯甲醇氧化制苯甲醛反应中表现出优异的催化活性,MgAl水滑石添加剂可有效地提高醛的选择性。 在苯甲醇1 mmol、乙腈2 mL、CoTPP 5 mg、MgAl水滑石18 mg、异丁醛5 mmol、反应温度60 ℃、氧气气氛下反应2 h,苯甲醇的转化率和苯甲醛的选择性分别达到94%和92%。 另外,此催化体系在其它醇类化合物的氧化反应中也具有较好催化活性。     

Oxovanadium(V)-Catalyzed Deoxygenative Coupling Reaction of Alcohols with Trimethylsilyl Enol Ethers in the Presence of MS3A

Oxovanadium(V)-catalyzed deoxygenative coupling reaction of allyl alcohols with trimethylsilyl enol ethers was demonstrated to afford γ,δ-unsaturated carbonyl compounds in one-step. The catalytic deoxygenative coupling reaction of allyl alcohols proceeded smoothly with both aromatic and aliphatic trimethylsilyl enol ethers. This catalytic deoxygenative coupling system could be applied to the deoxygenative coupling reaction of benzyl alcohols with trimethylsilyl enol ethers, providing the corresponding carbonyl compounds. Furthermore, a gram-scale catalytic synthesis of the γ,δ-unsaturated carbonyl compound was successfully performed to validate the scalability of this catalytic deoxygenative coupling reaction.     

Highly Chemoselective Aerobic Oxidation of Amino Alcohols into Amino Carbonyl Compounds

The direct oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has often posed serious challenges in organic synthesis and has constrained chemists to adopting an indirect route, such as a protection/deprotection strategy, to attain their goal. Described herein is a highly chemoselective aerobic oxidation of unprotected amino alcohols to their amino carbonyl compounds in which 2‐azaadamantane N‐oxyl (AZADO)/copper catalysis is used. The catalytic system developed leads to the alcohol‐selective oxidation of various unprotected amino alcohols, carrying a primary, secondary, or tertiary amino group, in good to high yield at ambient temperature with exposure to air, thus offering flexibility in the synthesis of nitrogen‐containing compounds.