Syntheses of Ring-Fluorinated Isoquinolines and Quinolines via Intramolecular Substitution: Cyclization of 1,1-Difluoro-1-alkenes Bearing a Sulfonamide Moiety

On treatment of a base such as NaH, KH, or Et 3 N, N-[o-(2,2-difluorovinyl)ben7-yl]- and N-[o-(3,3-difluoroallyl)phenyl]-substituted p-toluenesulfonamides readily undergo intramolecular substitution of sulfonamide nitrogens for vinylic fluorines in a 6-endo-trig fashion, leading to 3-fluoroisoquinoline and 2-fluoro-quinoline derivatives, respectively, in high yields.