Radical Mechanism of IrⅢ/NiⅡ Metallaphotoredox-Catalyzed C(sp^(3))-H Functionalization Triggered by Proton-Coupled Electron Transfer:Theoretical Insight

作     者：Yu-Jiao Dong Bo Zhu Yun Geng Zhi-Wen Zhao Zhong-Min Su Wei Guan 

作者机构：Institute of Functional Material ChemistryFaculty of ChemistryNortheast Normal UniversityChangchun 130024 College of ChemistryJilin UniversityChangchun 130012 

出 版 物：《CCS Chemistry》 (中国化学会会刊（英文）)

年 卷 期：2022年第4卷第4期

页      面：1429-1440页

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

基　　金：financially supported by the NSFC(no.21773025) 

主　　题：C(sp^(3))-H functionalization photoredox catalysis iridium nickel density functional calculations 

摘      要：Photoredox catalysis can be induced to activate organic substrates or to modulate the oxidation state of transition-metal catalysts via unique singleelectron transfer processes,so as to achieve challenging C(sp^(3))-H functionalization under mild ***,the specific reaction mechanism and relevant electron transfer process still need to be ***,a highly regioselective Ir^(Ⅲ)/Ni^(Ⅱ)-metallaphotoredox-catalyzed hydroalkylation of asymmetrical internal alkyne with an etherα-hetero C(sp^(3))-H bond has been investigated by density functional theory(DFT)calculations.A novel radical mechanism was predicted to merge oxidative quenching(Ir^(Ⅲ)-*Ir^(Ⅲ)-Ir^(Ⅳ)-Ir^(Ⅲ))and nickel catalytic cycles(NiⅡ-NiⅢ-NiI-NiⅢ-NiⅡ)for this C(sp^(3))-H functionalization to construct C(sp^(3))-C(sp^(2))*** consists of seven major steps:the single-electron transfer involved in the photoredox cycle for generating active Ni(Ⅰ)-chloride complexes,proton-coupled electron transfer process to provide α-carbon-centered tetrahydrofuran(THF)radicals,radical capture by Ni(Ⅱ),reductive elimination to obtain 2-chlorotetrahydrofuran,alkyne oxidative hydrometallation,innersphere electron transfer,and σ-bond metathesis to yield the desired alkyne hydroalkylation ***,both the thermodynamic performance for redox potentials and the kinetic exploration for energy barriers and electron-transfer rates have also been evaluated for the corresponding electron transfer *** addition,the steric effects play a major role in determining the regioselectivity of alkyne oxidative hydrometallation.