Intermolecular Dehydrative [4 + 2] Aza-Annulation of N-Arylamides with Alkenes: A Direct and Divergent Entrance to Aza-Heterocycles

We disclose that following activation with trifluoromethanesulfonyl anhydride, secondary N-arylamides undergo smooth intermolecular dehydrative [4 + 2] aza-annulation with alkenes under mild conditions to give 3,4-dihydroquinolines, amenable to further functionalization. Meanwhile, conditions have been established to allow divergent one pot synthesis of tetrahydroquinolines and quinolines as well as tricyclic analogues from N-arylamides.