手性伯胺催化的不对称Aldol反应

<正>Aldol反应被认为是现代有机合成中最有效的形成碳碳键的方法之一[1],应用此反应可以合成含有两个立体中心的β-羟基羰基化合物。自从2000年List教授发现脯氨酸可以催化分子间的不对称Aldol反应以来[2],越来越多的科学家开始致力于寻找高效的有机催化剂。     

醛,酮,醇和胺的不对称合成

根据对866个有代表性的旋光物质的研究,H.J.Roth和A.Kleemann指出,半数以上的旋光物质是手性的,至少具有一个或一个以上手性中心。其中22％光活性物质来自天然产物或从天然产物通过部分合成得到。78％光活性物质是全合成的,但是纯的对映体仅占5％。众所周知,光学活性物质的对映体     

有机小分子催化的不对称胺化反应的研究进展

根据手性催化剂的类型并结合其反应机理,介绍了近几年来偶氮二羧酸酯参与的有机小分子催化的不对称胺化反应的研究进展.参考文献50篇.     

手性伯胺催化剂用于顺式选择性的不对称Cross-Aldol反应

基于酸碱作用,将手性伯胺与质子酸原位结合制得有机小分子催化剂,并用于醛与醛的不对称Cross-aldol反应.与一般手性仲胺催化剂不同,该类伯胺催化剂得到的是顺式选择性构型的Cross-aldol产物,其产率达90%,顺反比和ee值分别为9:1和90%.相比而言,采用简单易得的(1S,2S)-(+)-环己二胺即可得到较高选择性的顺式产物.     

手性胺-质子酸催化剂在有机催化不对称合成中的应用

手性胺-质子酸是近年来发展起来的新型高效、高对映选择性的有机催化体系, 已成功应用于催化不对称Aldol反应、Michael加成反应、Diels-Alder反应和Strecker反应等许多重要的有机合成反应. 价廉易得的质子酸的引入不仅可促进活性中间体烯胺的生成, 并可通过形成的氢键稳定反应的过渡态, 从而显著提高该催化体系的催化活性和立体选择性. 对各类手性胺-质子酸催化剂在有机催化不对称合成反应中的应用、不对称诱导反应的机理、手性胺和质子酸的分子结构对其催化活性和不对称诱导活性的影响进行了评述.     

镍催化均相不对称氢化反应研究进展

过渡金属络合物催化的均相不对称氢化反应是合成手性化合物的重要方法之一,目前主要集中于钌、铑、铱和钯等贵重过渡金属催化体系,这些贵重过渡金属催化体系面临着地球储量有限、价格昂贵和重金属污染环境等问题,因而发展地球储量丰富、价格低廉、无毒或低毒且对环境友好的铁、钴、镍和铜的均相不对称氢化反应催化体系符合现代化学可持续发展的要求和趋势.简要综述了近些年来廉价金属镍催化的均相不对称氢化反应研究领域的新进展,基于前手性不饱和化合物双键的不同类型,即碳-氧双键(C=O)、碳-碳双键(C=C)以及碳-氮双键(C=N)等,依次介绍它们的研究现状,目前已经取得了突破和可观的研究成果,系统地分析了镍催化体系中催化氢化不同类型底物的优势与不足,并展望了未来的研究方向.     

稀土金属在不对称催化中的应用:从均相催化到异相催化

稀土金属的配位数较高,可通过容纳大型手性配体,构筑手性环境,催化不对称反应的定向发生,在工业生产特别是制药工程中具有重要应用价值.本文以Henry反应、Mannich反应和Strecker反应为例,总结回顾了稀土金属催化剂在此类反应中的设计思路、性能特点与应用前景,旨在展现稀土金属催化剂兼具融合均相催化与异相催化的优势...     

过渡金属催化的不对称电化学进展

总结了近年来过渡金属催化的不对称电化学进展.过渡金属催化的不对称电化学(AOMCE)分为氧化和还原反应.在氧化反应方面,发展了烯烃的不对称官能团化,二级醇或醛的动力学拆分以及碳氢键的不对称官能团化反应.在还原反应部分包括二氧化碳的不对称电化学羧化、不对称电化学脱羧反应以及不对称还原偶联反应.手性配体和过渡金属催化剂与电...     

手性伯胺作为有机催化剂对亚胺的不对称反应研究进展

在不对称有机催化领域,手性伯胺化合物是一类特别的有机小分子催化剂.作为手性仲胺催化剂的补充,它可以与羰基化合物形成烯胺或者亚胺盐活性中间体来催化各类不对称反应,在许多不对称转化中具有高对映选择性.对亚胺化合物(包括反应过程中涉及到的亚胺中间体)的碳氮双键官能团的不对称1,2加成,是获得α位手性含氮化合物的有效手段.近年来手性伯胺催化剂对亚胺的高对映选择性的不对称反应取得了一定的进展,因此对这一领域进行了综述和展望.     

雪松胺醇-硼烷络合物催化的潜手性酮的不对称还原反应

雪松胺醇-硼烷络合物催化的潜手性酮的不对称还原反应     

Aerobic oxidative dehydrogenation of benzylamines catalyzed by a cyclometalated ruthenium complex

The ruthenium(III) complex bearing phenylpyridine as a cyclometalated ligand serves as an efficient catalyst for the aerobic oxidative dehydrogenation of benzylamines to the corresponding benzonitriles under mild conditions.     

Aerobic oxidative dehydrogenation of benzyl alcohols to benzaldehydes by using a cyclometalated ruthenium catalyst

The ruthenium(III) complex bearing phenylpyridine as a cyclometalated ligand serves as an efficient catalyst for the aerobic oxidative dehydrogenation of benzyl alcohols to the corresponding benzaldehydes under mild conditions and for the one-pot synthesis of benzonitriles from benzyl alcohols with ammonia.     

Coordination chemistry of an asymmetric P,N,O tridentate ligand containing primary phosphine, amine and alcohol donors

The asymmetric, heterodonor tridentate ligand 2(S)-amino-4-phosphinobutan-1-ol, S-PNO, has been prepared from (S)-aspartic acid and some aspects of its coordination chemistry with a number of metal complexes investigated. Reaction of S-PNO with appropriate metal precursors led to the isolation of the complexes fac-Cr(CO)₃(κ³-S-PNO), 1, fac-[Mn(CO)₃(κ³-S-PNO)]PF₆, 2, and fac-[Re(CO)₃(κ³-S-PNO)]BF₄, 3. The alcohol and amine donors in fac-Cr(CO)₃(κ³-S-PNO) were substituted upon addition of trivinylphosphine to 1 to give the complex fac-Cr(CO)₃(κ¹-P-S-PNO){P(C₂H₃)₃}₂, 4. Addition of base to 4 gave a coordinated linear tridentate P₃ ligand through the formation of two new chelate rings via hydrophosphination of one vinyl group on each coordinated P(C₂H₃)₃ with the P-H bonds of the complexed S-PNO. The alcohol donor in fac-[Re(CO)₃(κ³-S-PNO)]BF₄ is labile and can be substituted with tris(2-fluorophenyl)phosphine, PAr₃^F, to give fac-[Re(CO)₃(κ²-P,N-S-PNO)(PAr₃^F)]BF₄, 5. Attempts to form a macrocyclic ligand through addition of base to fac-[Re(CO)₃(κ²-P,N-S-PNO)(PAr₃^F)]BF₄ were unsuccessful due to loss of PAr₃^F prior to any ring-closure. All the complexes have been fully characterised by spectroscopic and analytical techniques including a single-crystal X-ray structure analysis of 2.     

Air-stable iron catalyst for the Oppenauer-type oxidation of alcohols

An alcohol oxidation process using an air-stable iron tricarbonyl compound structurally similar to Shvo’s diruthenium bridging hydride was developed. Secondary benzylic and allylic alcohols are oxidized in high yields, and evidence for an Oppenauer-type mechanism is presented.     

The catalytic activity of a cyclometalated ruthenium(III) complex for aerobic oxidative dehydrogenation of benzylamines

The ruthenium(III) complex bearing benzo[h]quinoline as a cyclometalated ligand was synthesized and characterized by ESI-MS, elemental analysis, cyclic voltammetry and crystallography. The complex serves as an efficient catalyst for the aerobic oxidative dehydrogenation of benzylamines to the corresponding benzonitriles under mild conditions.     

First asymmetric synthesis of β-amino-β-trifluoromethylated aldehyde

The first asymmetric synthesis of the β-trifluoromethylated β-amino aldehyde, which is one of the most promising precursors for the synthesis of trifluoromethylated bioactive compounds, is described.     

Palladium catalyzed N-alkylation of amines with alcohols

An iron oxide immobilized palladium catalyst was prepared for the N-alkylation of amines with alcohols under base and organic ligand free conditions. Applying the optimized reaction conditions, the coupling reactions of amines and alcohols with various structures could be realized with up to 99% isolated yields. The catalysts were studied by XRD, BET, and XPS and the mechanism was studied by DFT calculations.     

Combining chiral elements: a novel approach to asymmetric phase-transfer catalyst design

A new dicationic asymmetric phase-transfer catalyst, designed by combining chiral elements, is described. Catalytic testing using standard glycine imino ester alkylations shows good yields and moderate enantioselectivities.