Production of 4-hydroxy-1,2-benzothiazine-3-carboxamides

Abstract

A process for the synthesis of N-aryl-3,4-dihydro-2-alkyl-4-oxo-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxides by treatment of N-aryl-N'-alkyl-N'-(2'-alkoxycarbonylbenzenesulfonyl)glycineamides, useful intermediates for said process, with an alkali or alkaline earth metal hydride in a reaction-inert solvent at 50°-150° C., said products being antiinflammatory agents.

What is claimed is: 
     
       1. A process for the preparation of a compound of the formula: ##STR10## wherein R 1  is selected from the group consisting of phenyl; monosubstituted phenyl wherein said substituent is selected from the group consisting of fluoro, chloro, methyl and methoxy; 2-thiazolyl; 4,5-dimethyl-2-thiazolyl; 2-pyridyl; 6-methyl-2-pyridyl, and 5-methyl-3-isoxazolyl; R 2  is alkyl containing from 1 to 3 carbon atoms; and   X is a substituent selected from the group consisting of hydrogen, methyl, methoxy, fluoro, chloro and bromo, which comprises contacting a compound of the formula: ##STR11## wherein R 3  is alkyl containing from 1 to 3 carbon atoms, with a metal hydride selected from the group consisting of alkali and alkaline earth metal hydrides, in a reaction-inert solvent at 50°-150° C.   
     
     
       2. The process of claim 1 wherein the metal hydride is sodium hydride. 
     
     
       3. The process of claim 2 wherein the solvent is tetrahydrofuran. 
     
     
       4. The process of claim 3 wherein X is hydrogen, and R 2  and R 3  are each methyl. 
     
     
       5. The process of claim 4 wherein R 1  is phenyl. 
     
     
       6. The process of claim 4 wherein R 1  is 2-thiazolyl. 
     
     
       7. The process of claim 4 wherein R 1  is 6-methyl-2-pyridyl. 
     
     
       8. The process of claim 4 wherein R 1  is 2-pyridyl.