Iridium-Catalyzed Aerobic alpha,beta-Dehydrogenation of gamma,delta-Unsaturated Amides and Acids: Activation of Both alpha- and beta-C-H bonds through an Allyl-Iridium Intermediate

Direct aerobic alpha,beta-dehydrogenation of gamma,delta-unsaturated amides and acids using a simple iridium/copper relay catalysis system is described. We developed a new strategy that overcomes the challenging issue associated with the low alpha-acidity of amides and acids. Instead of alpha-C-H metalation, this reaction proceeds by beta-C-H activation, which results in enhanced alpha-acidity. Conjugated dienamides and dienoic acids were synthesized in excellent yield with this reaction, which uses a simple reaction protocol. Mechanistic experiments suggest a catalyst resting state mechanism in which both alpha-C-H and beta-C-H cleavage is accelerated.