5-endo Heck-type cyclization of 2-(trifluoromethyl)allyl ketone oximes: synthesis of 4-difluoromethylene-substituted 1-pyrrolines

2-(Trifluoromethyl)allyl ketone O-pentafluorobenzoyloximes undergo a palladium-catalyzed 5-endo mode of alkene insertion via oxidative addition of the N-O bond, followed by beta-fluorine elimination to produce 4-difluoromethylene-1-pyrrolines.