Synthesis of 2-Substituted-4-hydroxy-2H-1, 2-benzothiazine-3-carboxlic acid 1, 1-dioxides from 2-Substituted-3, 4-dihydro-2H-1, 2-benzothiazin-4-one 1, 1-dioxides

2-치환-3, 4-Dihydro-2H- 1, 2-benzothiazin-4-one 1, 1-dioxides로부터 2-치환-4-Hydroxy-2H-1, 2-benzothiazine-3-carboxylic acid 1, 1-dioxides의 합성

2-Substituted-3, 4-dihydro-2H-1, 2-benzothiazin-4-one 1, 1-dioxide 6 was reatced with magnesium methyl carbonate to form magnesium chelate 7, which could be hydrolized in cold hydrochloric acid solution to give 2-substituted-4-hydroxy-2H, 1, 2-benzothiazine-3-Carboxylic acid 1, 1-dioxide 2 in good yield.