Helical Poly(quinoxaline-2,3-diyl)s Bearing 1,2,3-Triazole Pendants: Synthesis by CuAAC and Use as Reusable Abnormal NHC Ligands in Gold Catalysis

Poly(quinoxaline-2,3-diyl)s (PQXs) bearing 1,2,3-triazole pendants were synthesized by living copolymerization of achiral 1,2-diisocyanobenzenes or by post-polymerization functionalization of PQXs bearing alkyne pendants through copper-catalyzed azide-alkyne cycloaddition. Thus prepared PQXs bearing 1,2,3-triazole pendants were treated with MeI, Ag2O, and AuCl successively, giving polymer-supported gold complexes bearing 1,2,3-triazolylidenes as abnormal N-heterocyclic carbene (aNHC) ligands. The polymer-based aNHC ligand served as a catalyst for the reaction of styrene with a propargylic ester to form a cyclopropane derivative. The catalyst could be reused at least eight times without loss of activity.