Reaction of 2-Hydroxy-1,2,2-triphenylethyl Propionate with Non-Activated Ketones and Enones: Stereoselective Aldol and Michael Addition
作者:Manfred Braun、Brigitte Mai、Daniel Ridder
DOI:10.1002/1099-0690(200108)2001:16<3155::aid-ejoc3155>3.0.co;2-8
日期:2001.8
reaction of the silyl ketene acetal 2, derived from (R)-propionate 1, with the ketones 3a−d occurs in a stereoselective manner. The aldol product 4c is obtained from the enone 3c, whereas the homologous compound 3d undergoes a 1,4 addition and leads to the keto ester 5. The configurations of the deprotected aldol adduct 6 (obtained from 3c) and the Michael product 5 are determined by crystal structure
TiCl 4介导的(R)-丙酸酯1的甲硅烷基乙烯酮缩醛2与酮3a - d的Mukaiyama型反应与立体异构体发生。醛醇产物4c从烯酮3c获得,而同源化合物3d经历1,4加成并生成酮酸酯5。通过晶体结构分析确定脱保护的羟醛加合物6(从3c获得)和迈克尔产物5的构型。非对映体和对映体纯酯制备4a - c,5和6,以及包含两个或三个连续的立体碳中心的羧酸7和二醇8。对映体纯的化合物7和8是由可回收的手性辅助试剂1,1,2-三苯基-1,2-乙二醇的裂解产生的。