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

Abstract

We report the synthesis of a heterogenous silver catalyst stabilized by bidentate N-heterocyclic carbene ligands. The heterogeneous nature of the catalyst is inherently derived from the unprecedented internal structural features observed for the catalyst. X-ray studies show that the silver complex forms a two-dimensional cross-linked system, where one dimension of the network is formed by inorganic polymer strings and the second direction is formed by the interconnection of these inorganic strings with NHC bidentate ligands. This organized internal arrangement renders the complex insoluble in many common organic solvents and enables its utilization as a reusable heterogeneous catalyst in multicomponent A³ coupling reactions. Notably, propargylic amines were obtained with yields of up to 97%, and the catalyst demonstrated reusability for six cycles. These results can facilitate the further development of heterogeneous NHC catalysts.