当前位置: X-MOL 学术ACS Catal. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Mechanistic Study of Ni and Cu Dual Catalyst for Asymmetric C–C Bond Formation; Asymmetric Coupling of 1,3-Dienes with C-nucleophiles to Construct Vicinal Stereocenters
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-05-21 , DOI: 10.1021/acscatal.1c01626
Jingzhao Xia 1, 2 , Takahiro Hirai 1 , Shoichiro Katayama 1 , Haruki Nagae 1 , Wanbin Zhang 2 , Kazushi Mashima 1
Affiliation  

We report details of the reaction mechanism for a coupling reaction of 1,3-dienes with C-nucleophiles that was catalyzed by a Ni/Cu cooperative catalyst system using Ni(cod)2 and [Cu(CH3CN)4]PF6 in the presence of a chiral JOSIPHOS-type bisphosphine ligand and iPr2NEt, providing direct access to highly valuable vicinal quaternary and tertiary stereocenters with high enantio- and diastereoselectivity. The bimetallic cooperative catalyst system exhibited a broad substrate scope, including both cyclic/acyclic stabilized nucleophiles and aryl-/alkyl-substituted 1,3-dienes. The bimetallic cooperative catalyst mechanism was elucidated in depth by isolating and characterizing four key complexes of nickel and copper and conducting deuterium labeling experiments, kinetic studies, and density functional theory calculations. The turnover-limiting step of this reaction is the proton-transfer step to diene-coordinated Ni complex 6 from cationic Cu complex 8 to yield π-allyl Ni complex 7 and Cu enolate complex 9, respectively. The stereoselectivity of the reaction was also clarified according to single-point calculations of the key intermediates 7 and 9.

中文翻译:

Ni和Cu双催化剂形成不对称C-C键的机理研究;1,3-二烯与C-亲核试剂的不对称偶联构建邻位立体中心

我们报告了使用 Ni(cod) 2和 [Cu(CH 3 CN) 4 ]PF 6的 Ni/Cu 协同催化剂系统催化的 1,3-二烯与 C-亲核试剂偶联反应的反应机理的详细信息在手性 JOSIPHOS 型双膦配体和i Pr 2 存在下NEt,提供对具有高对映选择性和非对映选择性的高价值邻位四级和三级立体中心的直接访问。双金属协同催化剂体系表现出广泛的底物范围,包括环状/非环状稳定的亲核试剂和芳基/烷基取代的 1,3-二烯。通过分离和表征镍和铜的四种关键配合物并进行氘标记实验、动力学研究和密度泛函理论计算,深入阐明了双金属协同催化机理。该反应的转换限制步骤是质子转移步骤,从阳离子 Cu 配合物8到二烯配位的 Ni 配合物6,生成 π-烯丙基 Ni 配合物7和 Cu 烯醇化物配合物9, 分别。根据关键中间体79的单点计算也阐明了反应的立体选择性。
更新日期:2021-06-04
down
wechat
bug