Activation électrochimique du magnésium. Application à la synthèse de gem-difluoroalcènes par une réaction de Wittig électrochimique

Magnesium activation by electrochemistry. Application to the synthesis of gem-difluoroalkenes by an electrochemical Wittig reaction. The electrochemical reduction of bromodifluoromethyl tris-(dimethylamino)phosphonium tetrafluoroborate between a carbon felt cathode and a sacrificial magnesium anode in DMF led to difluoromethylene tris-(dimethylamino)phosphorane, which was reacted with aromatic or aliphatic aldehydes to give gem-difluoroalkenes in good yield. During these electrolysis, an electrochemical activation of the magnesium anode occurred. This phenomenon significantly reduced the electrolysis time, owing to direct chemical reduction of the phosphonium salt at the surface of activated magnesium rod.