Cooperative N-heterocyclic carbene Au and amino catalysis for continuous synthesis of secondary propargylamines in a fiber supported hydrophilic microenvironment

Abstract

A series of reusable and tunable polyacrylonitrile fiber supported catalysts that make use of the cooperative interplay between N-heterocyclic carbene (NHC) Au(III) and amino groups have been developed for synthesis of secondary propargylamines. The yield using immobilized NHC-Au(III) as catalyst is twice as much as that of its small molecule counterpart. Moreover, implementation of a flow system with polyacrylonitrile fiber supported NHC-Au(III) as catalyst leads to a short retention time of 3.3 min and an efficient productivity of 27 mmol/h. The highly catalytic activity of this catalyst is ascribed to the unique hydrophilic microenvironment consisting of NHC-Au(III), -NH2 and -CN groups in the surface of fiber catalyst. In this microenvironment, the adjacent NHC-Au(III) and amino groups promote the formation of gold-acetylide complex cooperatively with turnover numbers (TON) up to 5200.