Highly Enantioselective Michael Addition of 2-Oxindole-3-carboxylate Esters to Nitroolefins Promoted by Cinchona Alkaloid-Thiourea-Bronsted Acid Cocatalysts

A highly efficient organocatalyzed Michael addition of 2-oxindole-3-carboxylate esters to nitroolefins using a Cinchona alkaloid-thiourea and an achiral Bronsted acid as cooperative organocatalysts is reproted that affords significantly improved enantioselectivity and diastereoselectivity. It also provides an efficient approach to the synthesis of spirooxindole derivatives with high enantioselectivity.