Synthesis of α- C -Stereochemically Pure Secondary Sulfonamides.

A convenient "green" stereoretentive approach to sp 3 -enriched secondary sulfonamides bearing an asymmetric center at the α position to the sulfur atom is described. The method relies on the electrophilic amination of the corresponding stereochemically pure sulfinates with N -alkylhydroxylamine sulfonic acids (in turn easily prepared from N -alkylhydroxylamine and HSO 3 Cl). It is shown that the efficiency of the approach is governed mainly by steric factors; its tolerance to several functional groups (e.g., ether, phthalimide, or N -Boc carbamate) is also demonstrated.