Relay Photocatalytic Reaction of <i>N</i>-Aryl Amino Acids and 2-Bromo-3,3,3-trifluoropropene: Synthesis of 4-(Difluoromethylidene)-tetrahydroquinolines

Abstract

The bulk industrial chemical 2-bromo-3,3,3-trifluoropropene (BTP) was first employed as a coupling partner in photocatalytic defluorinative reactions with <i>N</i>-aryl amino acids. Photoredox activation of the C(sp²)-Br bond of the resultant 2-bromo-1,1-difluoroalkenes generates <i>gem</i>-difluoro vinyl radicals for further radical cyclization. Various 4-(difluoromethylidene)-tetrahydroquinolines were assembled in good yields by combining two photoredox cycles with a single photocatalyst.