In reactions of the dibromo compound 3-CH3-2-Me3SiOC4H6Br2 with n-butyl-lithium at −120°C one of the two diasterotopic bromine atoms is exchanged preferentially with a diastereoselectivity of 4/1. The resultant diastereomeric carbenoids have been trapped by isobutyraldehyde to give four diastereomeric epoxides in ca. 80% yield. Simple diastereoselection is reflected in the 2/1 Z/E ratio of the epoxides
在-120℃下,在二
溴化合物3-CH 3 -2-Me 3 SiOC 4 H 6 Br 2与
正丁基锂的反应中,两个非对映体
溴原子之一优先以非对映选择性为4/1进行交换。所得的非对映异构体类
胡萝卜素已被
异丁醛捕获,从而在大约1小时内得到了四个非对映异构体的
环氧化物。80%的产率。简单的非对映选择反映在
环氧化物的2/1 Z / E比中。