Copper-catalyzed synthesis of multifunctionalized 1,2-dihydropyridines using solid calcium carbide as an alternative to gaseous acetylene.

A variety of multifunctionalized 1,2-dihydropyridines are efficiently constructed through copper(I)-catalyzed one-pot three-component reactions using readily available 2-[(amino)methylene]malononitriles and sulfonyl azides, as well as inexpensive and easy-to-handle solid calcium carbide instead of flammable and explosive gaseous acetylene. This concise protocol enables the direct formation of important 1,2-dihydropyridines bearing amino, cyano, and sulfonylimino groups in one step by installing two C-N bonds and one C-C bond. This strategy has salient features of broad substrate scope, a low-cost catalyst, mild reaction conditions, high efficiency, simple workup procedures, and gram-scale applicability.