Hydroxy methyl 2h-benzothiazine carboxamide di:oxide prepn. - by reaction of the corresponding carboxylate with an amino-Grignard reagent to produce analgesics and antiinflammatories

摘要

Process for the prepn. of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamide -1,1-dioxide derivs. of formula (I) by reaction of an alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine 3-carboxylate-1,1-dioxide (III) with a Grignard reagent R-NH-Mg-X (IV), in an inert solvent, at 0-130 deg.C, until reaction is complete and then submit the intermediate to acid hydrolysis and recrystallise the prod. (I). In the formulae, R is phenyl or aryl substd. by halo (Cl, Br or I) or by 1-6C alkyl; 2,3 or 4-pyridyl or pyridyl substd. by halo (Cl, Br, I) or 1-6C alkyl; 5-methyl-isoxazolyl or 2-thiazolyl; R1 is 1-6C alkyl and X is halo. Used as analgesics and antiinflammatories.