KA2 Coupling, Catalyzed by Well-Defined NHC-Coordinated Copper(I): Straightforward and Efficient Construction of α-Tertiary Propargylamines**

Abstract

A new, straightforward, highly efficient, and mild catalytic protocol for the synthesis of α-tertiary propargylamines, via the multicomponent KA2 reaction (Ketone-Amine-Alkyne), employing well-defined, sustainable copper(I) complexes bearing N-heterocyclic carbene ligands, is reported herein. The methodology uses very low catalyst loading under moderate heating to achieve the construction of a wide range of propargylamines in good to excellent yields in very short reaction times. Challenging substrates, including acyclic linear ketones, aromatic ketones, and electron-poor aromatic alkynes, as well as substrates bearing synthetically valuable functionalities, are well tolerated.