3-Amino-5-methylisoxazole → 1-{[5-(4-hydroxy-2H-1,2-benzothiazin-3-yl)-1,2,4-oxadiazol-3-yl]methyl}ethanone

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A novel process for preparing 4-hydroxy-3-(5-methyl-3-isoxazolylcarbamoyl)-2-methyl-2H-1,2-benzothiazine 1,1-dioxide (I), starting with 3-amino-5-methylisoxazole (II) is disclosed. Compound I exhibits anti-inflammatory properties and is useful for treating inflammation. In the process of the invention an intermediate obtained, 2,3-dihydro-N-(5-methyl-3-isoxazolyl)-3-oxo-1,2-benzisothiazole-2-actamide 1,1-dioxide (IV) undergoes rearrangement to provide 1-{[5-(4-hydroxy-2H-1,2-benzothiazin-3-yl)-1,2,4-oxadiazol-3-yl]methyl}ethanone, S,S-dioxide (V), which is methylated, according to conventional procedures. The methylated intermediate VI, upon further treatment, undergoes a second rearrangement to obtain the desired anti-inflammatory compound I.

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