An enantioselective preparation of (S)-metolachlor has been accomplished. The synthetic route featured the asymmetric preparation of chiral intermediates and the final (S)-metolachlor from commercially available (R)-propylene oxide and a key Fukuyama’s process. The key steps, control points, separation purifications, and the whole process are optimized, and the target compound has been successfully prepared in five steps in 51–55% overall yield with excellent enantioselectivity (99% ee) up to a 30 g scale. By judicious choice of synthetic route and selection of starting materials and intermediates, no column chromatographic methods are needed for the separation and purification of the intermediates and the final products. The same strategy was extended as a general method for a series of pesticides and herbicide analogs of Metalaxyl-M and Dimethenamid-P.

中文翻译：

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从市售（R）-环氧丙烷对映选择性制备（S）-异丙甲草胺的优化合成路线

（S）甲草胺的对映选择性制备已完成。合成路线的特征是手性中间体的不对称制备和市售的最终（S）-甲虫草胺（R）-环氧丙烷和福山的关键工艺。对关键步骤，控制点，分离纯化和整个过程进行了优化，目标化合物已分五步成功制备，总收率在51％至55％之间，对映体选择性（99％ee）高达30 g。通过明智地选择合成途径以及选择起始原料和中间体，不需要柱色谱法来分离和纯化中间体和最终产物。扩展了相同的策略，将其作为甲霜灵-M和二甲胺磷-P的一系列农药和除草剂类似物的通用方法。