Palladium-catalyzed chemoselective intramolecular cyclization of bromoanilinoalkenenitriles

alpha-(o-Bromoanilino)alkenenitriles 1a-f and 2a-e and alpha-(N-alkenylamino)-beta-(o-bromophenyl)-propanenitriles 7a-c and 8a-c undergo palladium-catalyzed conversion into o-(methylamino)benzonitrile 12, o-[(alkenylamino)ethenyl]benzonitriles 24a-c, N-alkenylanilines 26b, 26c, 3-benzazepines 29a, 29c, 31a and 32a, gamma-carbolines 36 and pyrrolo[3,2-b]indole 45. The reactions involve intramolecular additions of arylpalladium to the cyano group and subsequent processes such as cyano group transposition, hydrolysis, electrocyclization, ethyl group transfer and oxidative aromatization. A general mechanism for the palladium-catalyzed arylation of a cyano group is proposed.