The Effect of Alkyllithium Reagent on Alkylation of Mono- and Disubstituted Vinyl Bromides via Halogen-Metal Exchange

Abstract

In the course of developing a stereospecific trisubstituted olefin synthesis¹ we required an efficient, procedurally easy, and reproducible method for generating vinyllithium species from vinyl bromides. Of the two most obvious methods, reaction with lithium metal^2,3 and halogen-metal exchange with alkyllithium reagents^3-6, we chose to examine the latter because it potentially presented the most convenient procedural method. Initial attempts utilizing n-butyllithium in tetrahydrofuran solvent at relatively low temperature (-78°C) proved disappointing, giving significant amounts of unreacted vinyl bromide even after 6h when using either (E)- or (Z)-5-bromo-5-decene. In order to approximate the amount of vinyllithium reagent formed we treated the resulting