Organocatalytic Domino Reaction of Cyanosulfones: Access to Complex Cyclohexane Systems with Quaternary Carbon Centers

When epsilon-nitro-alpha,beta-unsaturated esters are added to conjugated cyanosulfones in the presence of a bifunctional thiourea catalyst, a highly stereoselective domino reaction occurs to generate complex cyclohexanes with up to four stereogenic centers, one of which is quaternary in nature. Therefore, it is demonstrated that, like nitro compounds, sulfones can undergo an asymmetric intramolecular conjugate addition to alpha,beta-unsaturated esters in the presence of a bifunctional organocatalyst.