ABSTRACT Microwave assisted synthesis of a series of 4-hydroxy-N'-(phenylcarbonyl)-2H- 1, 2-benzothiazine-3-carbohydrazide 1, 1-dioxides from sodium saccharin is reported. Sodium o-benzosulfimide was N-alkylated with ethyl chloroacetate followed by base catalyzed ring expansion to six membered 1, 2-benzothiazine through Gabriel-Coleman type rearrangement yielding ethyl 4-hydroxy-2H-1, 2-benzothiazine-3-carboxylate 1, 1- ...
