Highly Enantioselective Hydrogenation of<i>N</i>-Aryl Imines Derived from Acetophenones by Using Ru-Pybox Complexes under Hydrogenation or Transfer Hydrogenation Conditions in Isopropanol
The asymmetric reduction of N‐arylimines derived from acetophenones by using Ru complexes bearing both a pybox (2,6‐bis(oxazoline)pyridine) and a monodentate phosphite ligand has been described. The catalysts show good activity with a diverse range of substrates, and deliver the amine products in very high levels of enantioselectivity (up to 99 %) under both hydrogenation and transfer hydrogenation
A combined experimental and computational study to decipher complexity in the asymmetric hydrogenation of imines with Ru catalysts bearing atropisomerizable ligands
DFT calculations reproduce accurately the ratio of isomers observed as well as the greater thermodynamic stability of the cis isomers of 1a. Complexes 1 are efficient catalyst precursors for the asymmetric hydrogenation of N-aryl imines 5 in toluene under very mild conditions using KOtBu as a base (4 bar H2, room temperature, 5/1/KOtBu = 500/1/10). Among the catalyst precursors, 1f provides good enantioselectivities
含有可阻转异构的膦-亚磷酸酯(P-OP)和手性C 2对称二胺(N-N)的RuCl 2(P-OP)(N-N)络合物(1)可以通过连续添加P轻松制备为反式异构体RuCl 2(PPh 3)3的–OP和N–N配体。对于这些络合物,已经观察到在室温下联芳基片段的快速阻转异构化。化合物反式- 1A干净异构成的混合物中的顺式异构体在EtOH在加热。DFT计算准确地再现了观察到的异构体的比例以及顺式的更大的热力学稳定性1a的异构体。配合物1是在非常温和的条件下,使用KO t Bu作为碱(4 bar H 2,室温,5 / 1 / KO t Bu = 500/1 / ,在非常温和的条件下,N-芳基亚胺5在甲苯中不对称氢化的有效催化剂前体。10)。在催化剂前体中,1f可在多种N-芳基亚胺的氢化反应中提供良好的对映选择性(84-96%ee,16个实例)。从DFT计算中,提出了一种机制,其中包括将氢化物和质子从二氢
Asymmetric Reductive Amination with Pinacolborane Catalyzed by Chiral SPINOL Borophosphates
作者:Zhenwei Wu、Hualing He、Minglei Chen、Linfei Zhu、Weitao Zheng、Yang Cao、Jon C. Antilla
DOI:10.1021/acs.orglett.2c03866
日期:2022.12.30
The catalyticasymmetric reductive amination of ketones with pinacolborane employing chiral SPINOL-derived borophosphates as catalysts has been realized. A series of chiral amine derivatives bearing multiple functional groups were obtained in good to excellent yields and enantioselectivities (up to 97% yield, 98% ee) under mild reaction conditions. Moreover, the synthetic applicability of the established
使用手性 SPINOL 衍生的硼磷酸盐作为催化剂,酮与频哪醇硼烷的催化不对称还原胺化反应已经实现。在温和的反应条件下,获得了一系列具有多个官能团的手性胺衍生物,具有良好至优异的产率和对映选择性(高达 97% 产率,98% ee)。此外,该方法的合成适用性已通过 ( R )-Fendiline 的不对称合成得到证明。
Li, Chaoqun; Villa-Marcos, Barbara; Xiao, Jianliang, Journal of the American Chemical Society, 2009, vol. 131, p. 6967 - 6969