Decarboxylative Alkynyl Termination of Palladium-Catalyzed Catellani Reaction: A Facile Synthesis of α-Alkynyl Anilines via Ortho C-H Amination and Alkynylation

A palladium-catalyzed synthesis of a-alkynyl anilines is reported. The reaction proceeds via Catellani ortho C-H amination followed by decarboxylative alkynylative amination. Different terminal alkyne precursors were screened, and it was found that alkynyl carboxylic acids were superior over other alkynes, which led to operationally simple reaction conditions (no gradual addition of alkynes) and broad substrate scope. The reactivity of three different components matched well; as a result, relatively higher reaction temperature could be used, greatly shortening the reaction time to 4 h from the previously reported 144 h.