Chiral Benzoins via Asymmetric Transfer Hemihydrogenation of Benzils: The Detail that Matters
作者:Lorena De Luca、Antonio Mezzetti
DOI:10.1021/acs.joc.9b03408
日期:2020.5.1
The synthesis of enantiomerically pure benzoins by hydrogenation of readily available benzils has been long thwarted by their base-sensitivity. We show here that an iron(II) hydride complex catalyzes the asymmetric transfer hydrogenation of benzils from 2-propanol. When strictly base-free conditions are granted, excellent enantioselectivity is achieved even with o-substituted substrates, which are
通过容易获得的苯偶酰氢化合成对映体纯的苯偶姻一直受到其碱敏感性的阻碍。我们在这里展示了一种铁 (II) 氢化物配合物催化 2-丙醇中苯偶酰的不对称转移氢化。当获得严格的无碱条件时,即使使用邻位取代的底物也能实现出色的对映选择性,这对于用其他方法制备特别具有挑战性。因此,在优化的反应条件下,在较短的反应时间(30-75 分钟)内以良好的收率(高达 83%)和优异的对映选择性(高达 98% ee)制备了手性安息香。此外,这项工作证实,当使用金属催化剂时,苯偶姻产物的两种对映异构体都可以得到,这明显优于酶法。