Ag(I) complexes of benzimidazol-2-ylidene ligands: a study of catalytic efficiencytowards three-component coupling reactions

Abstract

TheN-heterocyclic carbene (NHC){Ag(I) complexes3a{cwere synthesized from benzimidazolium chlorides(2a{c= NHC.HCl), incorporating benzyl derivatives and a 2-methoxyethyl group (a:3N = 2,4,6-trimethylbenzyl;b:3N = 2,3,5,6-tetramethylbenzyl;c:3N = pentamethylbenzyl). The compounds were characterized by spectroscopicand elemental analyses. The synthesized NHC{Ag(I) complexes (3a{c) were tested as catalysts for the catalytic three-component coupling reaction of aldehyde, alkyne, and amine to propargylamines in various solvents. All complexes wereactive catalysts for catalytic three-component coupling reactions with good yields under neat and mild conditions (after4 h, yields of up to 94%).