| 摘要 |
<p>4-Hydroxy-2-methyl N-(5-methyl 3-isoxazolyl) 2H-1,2-benzothiazine 3-carboxamide-1,1-dioxide (I) is prepd. by (a) reaction of 2-carboxymethyl saccharin (II) with 3-amino-5-methyl isoxazole (III) via the mixed anhydride of (II) with a chloroformate, the reaction being carried out in THF at 0 deg. C to ambient temp.; (b) opening the heterocyclic ring of the obtd. amide; and (c) methylation with MeI in ethanol soln. made alkaline with NaOH, at ambient temp.. The prod. is filtered off, washed with water and dried.</p> |
