Synthesis and Reactions of 3,3-Difluoro-2-exo-methylidene Indolines

[Image: see text] A dearomative electrophilic fluorination of 2-methylindoles is reported, delivering 3,3-difluoroindolines bearing an exomethylidene. The model substrate was synthesized on up to a 20 mmol scale and was purified by a practical recrystallization as a crystalline bench-stable, yet reactive solid. The olefin is amphoteric and can react both as a nucleophile and as an electrophile. A wide range of metal-free, palladium, rhodium, and copper reactions was explored, forming new C–H, C–B, C–C (alkyl and aryl), C–N, C–O, C–P, and C–S bonds.