用Sharpless不对称双羟化反应合成手性β-氨基醇

以烯烃为原料合成了一组对映体纯的β-氨基醇．在手性配体1,4-双(9-O-奎宁)-2,3-二氮杂萘[(QN)₂PHAL]存在下, 通过烯烃的Sharpless不对称双羟化、环化、亲核开环和催化氢化等步骤方便地合成了手性β-氨基醇. 从环氧化物到氨基醇的总产率为89%～94%, β-叠氮醇和β-氨基醇的光学纯度高达90%～99% ee. 同时考察了影响环氧化物开环的各种因素．     

一种可回收手性配体的合成及其对烯烃不对称二羟化反应的催化性能

 用1,4-二氟蒽醌与奎宁(QN)反应可高收率地得到1,4-双-(9-O-奎宁)蒽醌((QN)2AQN),再经OsO4氧化可得到带有4个羟基的手性配体. 在不对称二羟化反应的2种不同体系中,该配体对6种烯烃的反应表现出很高的对映选择性(80%～97%)和催化活性(80%～94%). 该配体不但具有金鸡纳生物碱衍生物小分子配体优异的立体选择性,同时也能象高聚物负载的大分子配体一样能够回收和重复使用,而且用量少,活性高,后处理简单. 在以反式肉桂酸乙酯为底物的不对称二羟化反应中,在t-BuOH-H2O/K3Fe(CN)6体系中循环使用5次(配体平均回收率93%),在Me2CO-H2O/NMO(N-甲基-N-氧吗啉)体系中循环使用8次,配体的催化活性和对映选择性基本保持不变.     

烯烃不对称双羟化反应中TentaGel树脂支载的可回收和重复使用的OsO_4催化剂研究

合成了在烯烃不对称双羟化反应中可回收和重复使用的TentaGel支载的OsO_4 催化剂。在DMF溶剂中，TentaGel HLBr与三乙胺反应生成季铵盐，在搅拌下后者与 K_2OsO_4饱和水溶液作用24 h，过滤，得TentaGel-OsO_4催化剂，用去离子水在索 氏提取器中连续提取24 h以除去吸附在TentaGel上未键合的K_2OsO_4。 TentaGel- OsO_4催化剂在反式-二苯乙烯的不对称双羟化反应中化学产率≥80%，立体选择性 ≥93% ee，而且连续使用五次，其催化活性不变。     

邻位取代1，2－二苯乙烯催化不对称二羟基化反应

邻位取代１，２－二苯乙烯催化不对称二羟基化反应张生勇，孙晓莉（第四军医大学化学教研室西安７１００３２）关键词　不对称二羟基化，手性二醇近年催化的反式稀烃的不对称二羟基化反应取得明显进展［１］，但催化的邻位取代的１，２－二苯乙烯类化合物的不对称二羟基化...     

Absolute Asymmetric Synthesis: Protected Substrate Oxidation

Three new conglomerates incorporating bidentate sulfide ligands coordinated by Ru^II centers have been prepared. Total spontaneous resolution by slow crystallization gives highly enantioenriched crystal batches, which are used in enantioselective oxidation of the sulfide ligands to give chiral sulfoxide complexes with >98 % ee. All relevant stereoisomers have been characterized by single‐crystal X‐ray diffraction, CD spectroscopy, and chiral HPLC. If the ligand range can be extended to monodentate sulfides, a large‐scale and recyclable process for enantioselective oxidation of sulfides can be designed.     

Asymmetric Dihydroxylation of Allylamine Catalyzed by Wool-OsO4 Complex

A new chiral polymer-metal complex, wool-osmium tetroxide(wool-OsO4) complex was prepared by a very simple method. This complex was found to be able to catalyze the asymmetric dihydroxylation of allylamine to get (R)-( )-3-amino-1, 2-propanediol. The experimental results showed that OsO4 content in the complex, reaction time, allylamine/OsO4 molar ratio all have great effects on the chemical and optical yields of product. Additionally, wool-OsO4 complex catalyst could be reused without remarkable change in optical catalytic activity.     

不对称有机合成和反应的分类

不对称有机合成和反应是制备对映纯化合物的方法之一,它具有广泛而不同的含义。对基于反应产物的“立体选择合成”,基于反应物的“立体辨别反应”和“去对称”以及基于不对称诱导方式的“代”分类方法作了介绍和评述。另外,对几个与不对称合成有关的制备对映纯化合物的方法也作了阐述。对“双重不对称合成”的立体化学,以Michael反应为例进行了讨论。参考文献34篇。     

A Soluble Block Copolymer-Supported bis-Cinchona Alkaloid Ligand for the Asymmetric Dihydroxylation of Olefins

Abstract

A soluble block copolymer-supported ligand was prepared via polycondensation of a bis-cinchona alkaloid derivative, polyethylene glycol, and terephthaloyl chloride. Its application in the asymmetric dihydroxylation of olefins delivered very good enantioselectivity.     

Rh(I)-Catalyzed Asymmetric Hydrosilylation and Hydroboration/Oxidation Reactions Using Berens Ligand

The Berens ligand 2 was used in a number of Rh(I)-catalyzed asymmetric hydrosilylations of acetophenones under standard conditions, affording the corresponding 1-arylalcohols in ees up to 65%. Some novel Rh catalysts were generated in situ from the neutral precatalyst [Rh(µ-Cl)(COD)]₂ and screened in the catalytic asymmetric hydroboration/oxidation of styrenes, gave enantioselectivities of up to 62%.     

Synthesis of a New Rigid Bicyclic AMPP Ligand （TIAMPP） and Application in Asymmetric Hydrogenation

The new rigid bicyclic AMPP（（S）-TIAMPP） has been synthesized from the corresponding Ticol and Ph2PCI. The application of （S）-TIAMPP in Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acids derivatives has been examined. Up to 93% ee was obtained.     

有机催化剂在不对称合成中的应用

根据不同结构类型综述了近几年来各种有机催化剂的特点、机理及其在不对称合成中的应用研究进展.