1,2-Benzothiazine Derivatives from Sulfonimidamides by Metal-Catalyzed Annulation Reactions in Solution and under Solvent-Free Mechanochemical Conditions

Abstract

Three-dimensional aza-analogues of 1,2-benzothiazine 1,1-dioxides have been prepared from sulfonimidamides. Two different protocols are presented. The first is a rhodium-catalyzed annulation reaction with α-sulfonyloxyketones leading to 4-unsubstituted benzothiazine derivatives. By selective bromination with NBS the heterocyclic ring can further be functionalized. In the second approach, an iridium catalyst is applied under solvent-free mechanochemical conditions providing products with 3,4-disubstituted thiazine rings from diazoketo esters and diazoketo sulfones. (Figure presented.).