Use of Trifluoromethyl Groups for Catalytic Benzylation and Alkylation with Subsequent Hydrodefluorination

The electrophilic organofluorophosphonium catalyst [(C 6 F 5 ) 3 PF][B(C 6 F 5 ) 4 ] is shown to effect benzylation or alkylation by aryl and alkyl CF 3 groups with subsequent hydrodefluorination, thus resulting in a net transformation of CF 3 into CH 2 –aryl fragments. In the case of alkyl CF 3 groups, Friedel–Crafts alkylation by the difluorocarbocation proceeded without cation rearrangement, in contrast to the corresponding reactions of alkyl monofluorides.