文献类型：期刊文献

英文题名：Theoretical Exploration of Mechanism and Ligand Effects of Asymmetric Hydrogenation of β-Amino Ketone Catalyzed by an Iridium-PNN Catalyst

作者：Xiong, Yan[1]; Liu, Chengyu[2]; Zhang, Lei[2]; Wang, Xin[1]; Yang, Jiaxin[3]; Liu, Zhen[1]; Ye, Jinxing[2,3]; Cheng, Ruihua[1,3]

机构：[1] School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China; [2] Engineering Research Centre of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, China; [3] School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, 510006, China

年份：2023

卷号：42

期号：9

起止页码：757

外文期刊名：Organometallics

收录：EI(收录号：20231914058727)

语种：英文

外文关键词：Amides - Amines - Binding energy - Catalysts - Chemical bonds - Density functional theory - Enantioselectivity - Iridium - Ketones - Ligands - Phosphorus compounds - Scaffolds - Sodium compounds

摘要：The Ir-PNN catalyst incorporating triaryl phosphine, secondary amine, and sulfonyl amide groups previously developed by our group has realized excellent enantioselectivities (up to 99% ee) in asymmetric hydrogenation of β-amino ketones. Based on this research, density functional theory calculations were employed to explore the possible reaction mechanisms. Due to the complex structure of the catalyst, the energy in terms of the rotation of the aryl sulfonyl group on the ligand was scanned to identify the most stable conformation for the calculation. In the presence of t-BuONa, Na+ prefers to transfer from the N atom to O atom to form an O-Na-O bond based on sulfonyl amide groups and isomerization, which is different from the coordination in the traditional hydrogenation mechanism. This coordination benefits the reaction. The positive synergy of Na+ with catalysts is verified by comparison of O-Na-O and N-H-O binding. The hydrogenation is suggested to proceed via a one-bond concerted reaction by N-H-O binding or one-bond concerted sequential hydrogenation. i-PrOH participates in H-H bond cleavage as the proton-carrier. Also, the unfavorable reaction paths of coordination of the NH groups with the substrate are explored. The computationally predicted enantioselectivities of various ligands are in accordance with the experimental results. The aryl sulfonyl group on the unsymmetrical vicinal diamine scaffold of the ligand has a significant effect on enantioselectivity, while the configuration of the unsymmetrical diamine is irrelevant to enantioselectivity. ? 2023 American Chemical Society