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.

Internal 2D networking of silver bromide with a bidentate N-heterocyclic carbene ligand enables the formation of an inherently heterogeneous reusable catalyst for multicomponent A3 coupling

“…Our primary objective is to showcase the efficiency of this newly synthesized heterogeneous catalyst through a multicomponent A 3 coupling reaction involving aldehydes, secondary amines, and alkynes, ultimately yielding propargylic amines. 23,31–36 While prior studies have relied on silver and other metal catalysts supported on solid materials for this reaction, 37–43 our research stands out as the first instance of executing the reaction in a heterogeneous manner without the need for any solid support. The central focus of our research is to assess the catalyst performance, emphasizing high yields and showcasing its recoverability and reusability, ensuring no loss of catalytic activity across multiple reaction cycles.…”