Insight into the mechanism of the arylation of arenes via norbornene relay palladation through meta-to para-selectivity

作     者：Shengnan Liu Qiong Wang Fang Huang Wenjuan Wang Chong Yang Jianbiao Liu Dezhan Chen 

作者机构：College of ChemistryChemical Engineering and Materials ScienceCollaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of ShandongInstitute of Molecular and Nano ScienceShandong Normal UniversityJinan 250014P.R.China 

出 版 物：《Organic Chemistry Frontiers》 (有机化学前沿（英文）)

年 卷 期：2022年第9卷第1期

页      面：129-139页

核心收录：

学科分类：07[理学] 070304[理学-物理化学(含∶化学物理)] 0806[工学-冶金工程] 0703[理学-化学] 0702[理学-物理学] 

基　　金：supported by the Natural Science Foundation of Shandong Province(ZR2019YQ11). 

主　　题：selectivity catalysis determining 

摘      要：A novel mechanism of the arylation of arenes via norbornene(NBE)relay palladation through meta-to para-selectivity was revealed via density functional theory(DFT)calculations.Our calculated results revealed that the reaction was initiated by a[mono-N-protected amino acid ligand(MPAA)–Pd]complex to activate at first the meta-C–H guided by the directing group(DG),and para-arylation was subsequently achieved by NBE relay palladation from meta-to para-position.Significantly,the palladium/norbornene(Pd/NBE)cooperative catalysis was catalyzed by a Pd–Ag bimetallic complex,which accounted for the experimental fact that no yield detected without Ag.The reaction pathway through para-to meta-selectivity was also investigated,while this pathway was kinetically unfavorable.The results revealed that the initial DG guided C–H site activation was the rate-determining step and played an important role in determining site-selectivity.The primary meta-activation was favorable in energy due to the less ring strain in the cyclic nitrile-coordinated C–H transition states in the meta position.Moreover,the perfect cooperation of a remote directing template and a transient mediator NBE through the alternating association with the Pd center achieved the relay through meta-to para-position.The present results provide a reasonable insight into the para-C–H arylation by the Pd/MPAA/NBE cooperative catalysis in conjunction with a precise DG and Ag(I)additive.