四川大学陈应春团队报道了钯催化的1,3-烯炔与亚胺和硼试剂的模块化和对映选择性顺式双官能化。相关研究成果于2021年10月20日发表在《美国化学会杂志》。

该文中，研究人员报道了钯（0）络合物可以介导前所未有的1,3-烯炔和N-磺酰亚胺区域选择性和立体选择性的分子间偶联反应，并且所得钯（II）物种与有机硼试剂进行级联Suzuki反应。不对称三组分过程的底物范围很大，并且以模块化和顺式双功能化的方式有效地构建了富含对映体的全碳四取代烯烃衍生物。

控制实验和密度泛函理论（DFT）计算证明钯（0）作为π-Lewis碱催化剂，通过化学选择性地与1,3-烯炔的烯烃部分形成η2-络合物，从而根据乙烯基原理增加炔基的亲核性，对映选择性地攻击亚胺。通过生成的π-烯丙基络合物的90°单键旋转形成氮杂帕拉达环戊烯中间体，确保炔基的真正的顺式碳钯化。此外，以甲酸为氢转移试剂，实现了钯（0）催化的1,3-烯炔与亚胺的对映选择性还原偶联。

附：英文原文

Title: Palladium-Catalyzed Modular and Enantioselective cis-Difunctionalization of 1,3-Enynes with Imines and Boronic Reagents

Author: Qing He, Lei Zhu, Zhen-Hong Yang, Bo Zhu, Qin Ouyang, Wei Du, Ying-Chun Chen

Issue&Volume: October 20, 2021

Abstract: Here we report that a palladium(0) complex can mediate the unprecedented intermolecular coupling reaction of 1,3-enynes and N-sulfonylimines regio- and stereoselectively, and the resultant palladium(II) species undergo a cascade Suzuki reaction with organoboronic reagents. The substrate scope is substantial for the asymmetric three-component process, and the enantioenriched all-carbon tetra-substituted alkene derivatives are efficiently constructed in a modular and cis-difunctionalized manner. Control experiments and density functional theory (DFT) calculations support the idea that the palladium(0) acts as a π-Lewis base catalyst by chemoselectively forming η2-complexes with the alkene moiety of 1,3-enynes, thus increasing the nucleophilicity of the alkyne group based on the principle of vinylogy, to attack imines enantioselectively. The preferable formation of aza-palladacyclopentene intermediates, via a 90° single bond rotation from the resultant π-allyl complex, guarantees the formal cis-carbopalladation of alkyne group. In addition, a palladium(0)-catalyzed enantioselective reductive coupling of 1,3-enyne and imine is realized by using formic acid as hydrogen transfer reagent.

DOI: 10.1021/jacs.1c09877

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09877