Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1976-03-10
1977-05-17
Ford, John M.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
424246, C07D27902
Patent
active
040241360
ABSTRACT:
An improved process for the preparation of 4-hydroxy-3-(5-methyl-3-isoxazolylcarbamoyl)-2-methyl-2H-1,2-benzothiazine 1,1-dioxide (I), a known anti-inflammatory agent, is described. The process involves the reaction of a solution of alkyl 2,3-dihydro-3-oxo-1,2-benzisothiazole-2-acetate 1,1-dioxide (II) in dimethylformamide, with an alkali metal alkoxide using the specific portions of reactants and carefully controlled reaction conditions. Acidification of the reaction mixture precipitates out alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide (III) in substantially pure form in high yields, without recrystallization. Product III is methylated on the sulfonamide nitrogen and reacted with 3-amino-5-methylisoxazole to obtain crude I. A further improvement in the process of the invention involves a more efficient method for purifying crude product I by solubilizing in dimethylformamide with heating to 125.degree. C. to 148.degree. C. The hot solution is filtered, and the filtrate is cooled to obtain crystalline product I.
REFERENCES:
patent: 3822258 (1974-07-01), Zinnes et al.
Fontsere Francisco Carrio
Genzer Jerome Daniel
Chow Frank S.
Ford John M.
Graddis Albert H.
Kelly Anne M.
Warner-Lambert & Company
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