Wittig gem-difluoroolefination of aldehydes with difluoromethyltriphenylphosphonium bromide

• A general approach for the synthesis of gem-difluoroolefins was developed.
• Difluoromethyltriphenylphosphonium bromide was found to be able to undergo Wittig reaction with aldehydes in the presence of base.
• A new approach for the preparation of difluoromethyltriphenylphosphonium bromide was developed.

Wittig reaction of aldehydes with difluoromethyltriphenylphosphonium bromide leading to gem-difluoroolefins in moderate yields is described. The reaction displays a good substrate scope including aryl, heteroaryl and α,β-unsaturated aldehydes. Difluoromethyltriphenylphosphonium bromide could be easily prepared and stored for a long time under air atmosphere. The salt exhibits high thermal stability demonstrated by thermogravimetric analysis. Its structure was confirmed by NMR spectroscopy and single crystal X-ray analysis.

Difluoromethyltriphenylphosphonium bromide, an easily prepared salt which exhibits high thermal stability, was found to be able to undergo Wittig reaction with aldehydes in the presence of base to afford corresponding gem-difluoroolefins in moderate yields.Figure optionsDownload as PowerPoint slide