First organocatalyzed asymmetric Michael addition of aldehydes to vinyl sulfones

graph The first asymmetric direct Michael addition of aldehydes to vinyl sulfones catalyzed by N-iPr-2,2 '-bipyrrolidine is described. 1,4-Adducts are obtained in good yields and enantioselectivities. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as shown previously for nitroolefins.