Enantioselective Tandem Michael Addition and Cyclization Reaction Enabled by Dual Organo/Copper Catalysis: Access to Functionalized 4H-Pyrans.

An enantioselective (3 + 3) annulation between 1,3-nitroenynes and α-cyano ketones has been developed using a cooperative organo/copper dual catalytic system. The transformation proceeds through an enantioselective Michael addition catalyzed by the synergistic effect of an organocatalyst and metal-ligand complex, followed by Lewis-acid-catalyzed annulation, furnishing pentasubstituted 4H-pyran derivatives in good yields and good to excellent enantioselectivities. Mechanistic investigations were conducted to elucidate the reaction pathway, and its practical applicability was demonstrated through a scale-up reaction and versatile post synthetic modifications.