Palladium‐Catalyzed Regioselective 5‐ exo ‐ O ‐Cyclization/Oxidative Heck Cascades from o ‐Alkynylbenzamides and Electron‐Deficient Alkenes

A Pd‐catalyzed 5‐ exo ‐selective oxycyclization/oxidative Heck coupling cascade is described, starting from readily available ortho ‐alkynylbenzamides and functionalized olefins. The key to a high regioselectivity in the cyclization step is the choice of catalyst and/or additives. Thus, Pd(OAc) 2 provides the desired 5‐ exo products predominantly, whereas with PdCl 2 or Pd(TFA) 2 , the corresponding 6‐ endo products prevail. The subsequent oxidative Heck‐type coupling takes place stereoselectively with the very predominant formation of E isomers, leading to an effective preparation of structurally diverse carbonyl‐substituted allylideneisobenzofuranimines.