Facile Synthesis of 1,1-Difluoroallenes via the Difluorovinylidenation of Aldehydes and Ketones

Abstract

2-Bromo-3,3-difluoroallylic acetates were readily prepared by the reaction of carbonyl compounds with 1-bromo-2,2-difluorovinyllithium, generated from 1,1-dibromo-2,2-difluoroethylene, followed by acetylation. On treatment with butyllithium, the bromoacetates underwent selective 1,2-elimination of lithium acetate to afford mono- and disubstituted 1,1-difluoroallenes in high yields.