PROCESS FOR THE PREPARATION OF (-)-1,4-BENZOTHIAZINE-2-ACETIC ACID DERIVATIVES

摘要

A process for the preparation of (-)-1,4-benzothiazine-2-acetic acid derivatives, characterized by conducting the optical resolution of a racemic modification of a 1,4-benzothiazine-2-acetic acid derivative represented by general formula (I) by forming a salt of the (-)-enantiomer of the derivative with an optically active substance: (wherein R<1> and R<2> are each hydrogen or the like; R<3> is carboxyl or the like; R<4>, R<5>, R<6> and R<7> are each hydrogen, halogeno, or the like; and X is oxygen or the like). This process makes it possible to separate (-)-1,4-benzothiazine-2-acetic acid derivatives respectively from the corresponding (+/-)-1,4-benzothiazine-2-acetic acid derivatives in high yield and at high optical purity.