Highly Diastereoselective Formation of 1,2,3-Trisubstituted Cyclopropane Derivatives

A highly diastereoselective formation of cyclopropane derivatives was reported. When the chiral phenylvinyl epoxide reacted with lithiated
2-alkyl-1,3-dithiane or lithiated alkyl carbonanion in the presence of HMPA, cyclopropanes bearing stereochemistry at all three positions on
the ring were readily obtained in high yields of 80−97% and high dr values of 68:32−99:1. This reaction was supposed to be a tandem
conjugation addition−epoxide opening sequence.

本研究报道了一种高非对映选择性的环丙烷衍生物合成方法。当手性苯基乙烯基环氧化物在六甲基磷酰三胺（HMPA）存在下，与锂化2-烷基-1,3-二噻烷或锂化烷基碳负离子反应时，可得到环上三个位点均具有立体化学构型的环丙烷产物，产率为80%~97%，非对映选择性比（dr）为68:32~99:1。该反应被认为遵循串联共轭加成-环氧开环的反应历程。