Synthèse de “sulfahydatoïnes” chirales. Aspects stéréochimiques et protection régiospécifique.

Abstract

The enantiospecific synthesis of N 2-benzyl-1-thia-2,5-diazolidin-3-one dioxides (sulfa-analogues of hydantoins) was carried out through two convergent pathways starting from chlorosulfonyl isocyanate (CSI) and chiral α-amino- and hydroxyesters. The intermediate carboxylsulfamides (containing “activated sulfamoyl group”) react easily in the Mitsunobu conditions to give ultimately the N-protected sulfa-hydantoins, or symmetric and dissymmetric sulfones of bis-N-aminoesters. The non-racemization during the cyclization of N-sulfamylaminoesters in alkaline conditions was established by chemical and spectroscopic methods (nmr with chiral Eu(hfc) 3).