A process for preparing a single enantiomer of a 4-aryloxyazetidin-2-one derivative in optically pure form comprises reacting a hindered vinyl ester with chlorosulphonyl isocyanate; displacing the hindered acyloxy group with a phenolic derivative containing a protected carboxy group; deprotecting the carboxylate moiety; resolving with a chiral amine; filtering; and regenerating the desired enantiomer by acidification. A method for enriching the product obtained from the acyloxy displacement step in favour of the desired enantiomeric form, by treating with an asymmetric catalyst such as a chiral alkaloid derivative, is provided; as also is a method for racemising the unwanted antipode of the desired 4-aryloxyazetidin-2-one enantiomer. The invention further provides novel enantiomers based on the 4-aryloxyazetidin-2-one ring structure.
一种制备光学纯形式的 4-芳氧基氮杂环丁-2-酮衍
生物的单一对映体的工艺包括:使受阻
乙烯基酯与
氯磺酰异氰酸酯反应;用含有受保护羧基的
酚类衍
生物置换受阻酰氧基;脱保护羧基;用手性胺分解;过滤;以及通过酸化再生所需的对映体。本发明提供了一种方法,通过使用不对称催化剂(如手性
生物碱衍
生物)处理,使从酰氧基置换步骤中得到的产物富集成所需的对映体形式;还提供了一种方法,使所需的 4-芳氧基氮杂环丁-2-酮对映体的无用反式消旋化。本发明进一步提供了基于 4-芳氧基氮杂环丁-2-酮环结构的新型对映体。