Copper-Catalyzed Annulative Coupling of S,S-Disubstituted Enones with Diazo Compounds to Access Highly Functionalized Thiophene Derivatives.

An efficient protocol toward fully substituted thiophenes and thieno[2,3-b]thiophenes has been developed through CuCl2-catalyzed annulative coupling of S,S-disubstituted enones with diazo compounds under mild conditions. Tetrasubstituted thiophenes and thieno[2,3-b]thiophenes were efficiently accessed by variation of the feed ratio of the reactants in good to excellent yields, respectively. The synthetic methodology has demonstrated the potential for the construction of diverse thiophene derivatives.