The generation of difluoroenolates from trifluoroethanol and reproducible syntheses of α,α-difluoro-β-hydroxy ketones

Abstract

Metallated difluoroenol carbamate 1 reacted with aldehydes and ketones in the presence of highly oxophilic Lewis acid boron trifluoride–ethyl ether; the Lewis acid attenuated the transacylation reaction to the corresponding enolates so that allylic alcohols could be isolated. Treatment of the allylic alcohols with strong base afforded difluoroenolates which could be trapped cleanly in aldol reactions.