Enantioselective acyl transfer catalysts and their use in kinetic resolution of alcohols and desymmetrization of meso-diols
申请人:Birman Vladimir
公开号:US20050256150A1
公开(公告)日:2005-11-17
Novel enantioselective acylation catalysts comprising chiral derivatives of DHIP and DHIQ, having the following representative general structures are disclosed:
These new compounds are useful for resolving racemates or further enhancing the enantiomeric excess of an enantiomerically enriched composition and for desymmetrizing meso compounds.
2,3-Dihydroimidazo[1,2-a]pyridines: A New Class of Enantioselective Acyl Transfer Catalysts and Their Use in Kinetic Resolution of Alcohols
作者:Vladimir B. Birman、Eric W. Uffman、Hui Jiang、Ximin Li、Corey J. Kilbane
DOI:10.1021/ja0491477
日期:2004.10.1
unexplored 2,3-dihydroimidazo[1,2-a]pyridine (DHIP) has been shown to be a competent acyl transfer catalyst. Its chiral 2-phenyl derivatives obtainable in two steps from commercially available starting materials have proved to be effective acylation catalysts, giving high levels of enantioselectivity (s = 20-85) in kineticresolution of secondary benzylic alcohols. A transition state model explaining
Effects of Methyl Substituents on the Activity and Enantioselectivity of Homobenzotetramisole-Based Catalysts in the Kinetic Resolution of Alcohols
作者:Yuhua Zhang、Vladimir B. Birman
DOI:10.1002/adsc.200900383
日期:2009.10
Substitution of the tetrahydropyrimidine ring in enantioselective acyl transfer catalyst homobenzotetramisole (HBTM) 6 with methyl groups exerts a dramatic influence on its performance in the kineticresolution of secondary alcohols. Syn-3-Methyl analogue of HBTM (9a) has proved to be superior to the parent compound in terms of catalytic activity, enantioselectivity, and synthetic accessibility.
(R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) catalyzed kinetic resolution of racemic secondary benzylic alcohols with free carboxylic acids by asymmetric esterification
作者:Kenya Nakata、Isamu Shiina
DOI:10.1039/c1ob05736g
日期:——
the kineticresolution of racemic secondary benzylic alcohols in the presence of achiral carboxylicacids and pivalic anhydride. The use of a tertiary amine in this reaction is not necessary to attain good chemical yields of the products. It was determined that diphenylacetic acid could be employed as the most suitable acyl donor for achieving a high enantioselectivity for the kineticresolution of
Kinetic Resolution of Racemic Secondary Benzylic Alcohols by the Enantioselective Esterification Using Pyridine-3-carboxylic Anhydride (3-PCA) with Chiral Acyl-Transfer Catalysts
production of chiralcarboxylic esters by the combination of chiral nucleophilic catalyst, such as tetramisole (=2,3,5,6‐tetrahydro‐6‐phenylimidazo[2,1‐b][1,3]thiazole) derivatives. An efficient kineticresolution of racemic benzylic alcohols with achiralcarboxylicacids was achieved by using 3‐PCA in the presence of (R)‐benzotetramisole ((R)‐BTM), and a variety of optically active carboxylic esters were
发现吡啶-3-羧酸酐(3-PCA)是一种有效的偶联剂,可在温和的条件下通过简单的实验程序从各种羧酸与醇制备羧酸酯。这种新型缩合剂3-PCA不仅适用于由4-(二甲氨基)吡啶(DMAP)催化的非手性羧酸酯的合成,而且还适用于通过手性亲核催化剂(如四甲酚( = 2,3,5,6-四氢-6-苯基咪唑[2,1- b ] [1,3]噻唑)衍生物。在(R)-苯并四咪唑((R)-BTM),并且通过这种新的手性诱导系统在不使用叔胺的情况下生产了具有高对映体过量的多种旋光羧酸酯。