α, α-gem-Difluorination of α-(Alkylthio)acetophenone Derivatives with N-Fluoropyridinium Salts

Abstract

The α, α-gem-difluorination of 2', 4'-difluoro-α-(methylthio)acetophenone (1a) with N-fluoropyridinium salts gave 2', 4', α, α-tetrafluoro α-(methylthio)acetophenone (3a). This reaction was accelerated by the addition of zinc chloride, zinc bromide or anhydrous iron(III) chloride, and higher yields than the reaction without additives were obtained. The gem-difluorination reaction using FP-T300 in the presence of zinc bromide was applicable to other α-(alkylthio)acetophenone derivatives (1).