In this article, we present the development of a synthetic methodology based on homogeneous catalysis for the preparation of enantioenriched L-Valine aminoacid. The enantioselective hydrogenation of 5-methylenhydantoin has been developed through broad screenings of chiral ligands, metal precursors and reaction conditions including scale-up experiments and recyclability studies. A palladium catalyzed asymmetric hydrogenation of 5-methylenhydantoin afforded the corresponding hydrogenated product in a 70% enantiomeric excess using a substrate/catalyst ratio of 500/1. A partial racemization was observed upon hydrolysis and recovery of L-Valine.

中文翻译：

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均相钯催化5-甲基乙内酰脲的对映选择性加氢合成L-缬氨酸

在本文中，我们介绍了基于均相催化制备对映体富集的L-缬氨酸氨基酸的合成方法的开发。通过广泛筛选手性配体，金属前体和反应条件，包括扩大规模的实验和可回收性研究，已经开发了5-甲基乙内酰脲的对映选择性氢化。使用500/1的底物/催化剂比例，钯催化的5-甲基乙内酰脲的不对称氢化得到对映体过量70％的相应氢化产物。在水解和回收L-缬氨酸时观察到部分消旋。