One-pot synthesis of gem-difluorostyrenes from benzyl bromide via olefination of phosphonium ylide with difluorocarbene

A new approach for the synthesis of gem-difluorostyrenes from benzyl bromide is described. Quatemization of triphenylphosphine with benzyl bromide to give phosphonium salts, deprotonation of the corresponding phosphonium salts to produce phosphonium ylide, and the subsequent olefination of phosphonium ylide with difluorocarbene generated from difluoromethylene phosphobetaine (Ph3P+CF2CO2-) by decarboxylation can occur smoothly in one-pot, furnishing the final gem-difluorostyrenes in good yields. (C) 2015 Elsevier B.V. All rights reserved.