Indium(III)-Catalyzed Cationic Cyclization of 1,1-Difluoroallenes: Regioselective Synthesis of 1-Fluoronaphthalenes

Abstract

Abstract 1,1-Difluoroallenes underwent InBr3-catalyzed ring construction via in situ-generated allylic CF2 cations to give 1-fluoronaphthalenes in good yield. DFT calculations suggested that a positive charge was localized on the CF2 carbon in the key allylic CF2 cation, which was stabilized by (1) α-cation stabilizing effect of the fluorines and (2) hyperconjugation with the adjuscent C–In σ bond.