organozinc, to yield an equilibrium mixture, favoring the migration of alkenyl groups from boron to zinc. Addition of an aldehyde to the 2:3 reaction mixture, in the presence of 10 mol % N-methylpiperidine, results in the exclusive transfer of both alkenyl groups from zinc, furnishing diastereomerically pure trisubstituted double bnds in allylic alcohols in good to excellent yields.
(Z)-
三烯基
硼烷,(R 1 HC = CR 2)3 B,可以通过将相应的
炔烃与BMS在THF中进行氢
硼化而轻松制备,并在烃溶剂中与市售的
二乙基锌迅速反应,以1:3或2:3或
硼烷与
有机锌的比例达到平衡,从而有利于烯基从
硼向
锌的迁移。在10 mol%
N-甲基哌啶的存在下,向2:3反应混合物中添加醛会导致两个烯基从
锌中排他性转移,从而在烯丙基醇中提供非对映异构纯的三取代双键,收率很好。