Sterically Hindered Chiral Ferrocenyl P,N,N-Ligands for Highly Diastereo-/Enantioselective Ir-Catalyzed Hydrogenation of α-Alkyl-β-ketoesters via Dynamic Kinetic Resolution
作者:Chuan-Jin Hou、Xiang-Ping Hu
DOI:10.1021/acs.orglett.6b02828
日期:2016.11.4
A new class of sterically hindered chiral ferrocenyl P,N,N-ligands have been prepared through a two-step transformation from (Sc,Rp)-PPFNH2, in which a new (R)-stereogenic center at the pyridinylmethyl position was generated in high diastereoselectivity. With these newly developed P,N,N-ligands, Ir-catalyzed asymmetric hydrogenation of various α-alkyl-substituted β-aryl-β-ketoesters via dynamic kinetic
通过从(S c,R p)-PPFNH 2的两步转化制备了新型的空间位阻性手性二茂铁基二茂铁基P,N,N-配体,其中在吡啶基甲基位置上有一个新的(R)-立体异构中心产生的非对映异构体选择性高。借助这些新开发的P,N,N配体,首次在高非对映体和对映体选择性下,通过动态动力学拆分实现了Ir催化的各种α-烷基取代的β-芳基-β-酮酸酯的不对称氢化,导致了多种光学活性的反-β-羟基酯含量高达99%ee。研究表明,这些配体的吡啶基甲基位置上的额外立体中心对于实现这种氢化作用至关重要。