The TiCl4-mediated reaction of enone 3 with the silyl ketene acetal 2 derived from (R)-propionate 1 occurs in a stereoselective manner. The major aldol adduct 4, whose configuration was proven by an X-ray structure analysis of 6, affords the enantiomerically pure carboxylic acid 5 upon hydrolysis.
TiCl4 介导的烯酮 3 与源自 (R)-
丙酸酯 1 的
硅酮
缩醛 2 的反应具有立体选择性。主要的醛醇加合物 4(其构型已通过对 6 的 X 射线结构分析得到证实)在
水解后可生成对映体纯的
羧酸 5。