Process for preparing 2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide derivatives and intermediates therefor

摘要

The process for the preparation of derivatives of 2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide of the formula <IMAGE> wherein R represents hydroxy (Ia) or substituted hydroxy OR1 in which R1 is the cinnamoyl radical -CO-CH=CH-C6H5 (Ib) consists in reacting a strong base salt of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid 1,1-dioxide with an acyl chloride R1Cl, in which R1 is the cinnamoyl radical, or R2Cl, in which R2 is an aromatic or aliphatic C2-C6 acyl radical to give the corresponding mixed anhydride, optionally esterified at position 4, which is then reacted with 2-aminopyridine to give the desired amide.