REGIOSELECTIVITY OF THE ADDITION OF α-METALLATED N,N-DIMETHYL SULFONAMIDES TO α,β-UNSATURATED CARBONYL COMPOUNDS

Abstract

The regioselectivity of the addition of lithiated sulfonamides covers all the possible variations, from pure 1,2- or pure 1,4-additions to mixtures of the two. The 1,2- vs 1,4-addition competition is directed by the “hardness” of sulfonamide “carbanions” in terms of stronger preferance of the aldol type addition, on one hand, and by factors such as the steric bulk of the attacking “carbanions” and metal salt dissociation or aggregation in the solvent which retard the 1,2- more than the 1,4-addition, on the other hand.

Key Words:

• α-Metallated N,N-dimethylsulfonamides
• β-hydroxysulfonamides
• δ-ketosulfonamides
• α,β-unsaturated carbonyl compounds
• regioselectivity, 1,2- vs 1,4-addition.