A N-heterocyclic carbene derived highly regioselective ambident C–C–S and C–C–N 1,3-dipolar system

Abstract

N-Heterocyclic carbene derived 2-phenylthiocarbamoyl benzimidazolium and imidazolinium inner salts are a unique ambident C–C–S and C–C–N 1,3-dipolar system able to undergo highly efficient and regioselective cycloaddition with dimethyl acetylenedicarboxylate and ethyl propiolate to furnish, respectively, spiro[imidazole-2,3′-thiophene] and spiro[imidazole-2,3′-pyrrole] derivatives in good to excellent yields.