Reductive Cyclization of Bromoenynamides with Alcohols as Hydride Source: Synthesis and Reactions of 2‐Amidodienes

Under basic conditions in alcoholic solvents, bromoenynamides undergo palladium‐catalyzed cyclization to cyclic 2‐amidodienes in good to excellent yields. This process represents the first use of an alcohol as a hydride source in an alkyne carbopalladation/termination sequence, with the site selectivity of the reduction showing a strong dependence on the tethering ring size (5–8), and the nature of the alcohol and base. Reaction of the dienes with a range of dienophiles (including alkenes, alkynes and arynes) under various conditions gives bi‐ and tricyclic azacycles, which can be further oxidized to the aromatic azacycles.