The present invention provides a process for the preparation of optically active carboxylic acids of the formula I* or II* ##STR1## in which X is an oxygen or sulfur atom and n is 1 or 2. The process comprises reacting a racemic carboxylic acid I or II or its derivatives with an optically active 2-amino-carboxylic acid ester to give the diastereomeric carboxylic acid amides, separating the diastereomers and, after cleavage of the amide bond, isolating the optically active carboxylic acids of the general formula I* or II*. The invention also provides certain novel optically active carboxylic acid amides and a tetrahydrothiopyran-2-carboxylic acid.
本发明提供了一种制备光学活性
羧酸的方法,其
化学式为I*或II*##STR1##其中X是氧或
硫原子,n为1或2。该方法包括将外消旋
羧酸I或II或其衍
生物与光学活性的2-
氨基
羧酸酯反应,得到对映异构的
羧酸酰胺,分离对映异构体,并在酰胺键断裂后分离出一般式I*或II*的光学活性
羧酸。本发明还提供了某些新型光学活性
羧酸酰胺和
四氢噻吩-2-
羧酸。