Palladium‐Catalyzed [3+3] Annulation between Diarylamines and α,β‐Unsaturated Acids through CH Activation: Direct Access to 4‐Substituted 2‐Quinolinones

A C-H activation strategy has been successfully employed for the high-yielding synthesis of a diverse array of 4-substituted 2-quinolinone species by a palladium-catalyzed dehydrogenative coupling involving diarylamines. This intermolecular annulation approach incorporates readily available α,β-unsaturated carboxylic acids as the coupling partner by suppressing the facile decarboxylation. Based on preliminary mechanistic studies, a reaction sequence is proposed, involving ortho palladation, π-coordination, β-migratory insertion, and β-hydride elimination.