Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System
Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System
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DOI：
10.1021/jacs.2c01705
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发表时间：
2022-04-13
影响因子：
15
通讯作者：
Kanai, Motomu
中科院分区：
文献类型：
--
作者：
Fuse, Hiromu;Irie, Yu;Kanai, Motomu
我们开发了有机催化剂体系，通过氢原子转移（HAT）过程促进稳定C-H键（如甲酰基、α-羟基和苄基C-H键）的裂解，而不使用外源光敏剂。电子调谐硫代磷酸（7，7 ′-OMe-TPA）与底物或助催化剂N-杂环芳烃通过氢键和π-π相互作用组装成电子给体-受体（EDA）复合物，EDA复合物经光照射诱导逐步、顺序的单电子转移（SET）过程，产生HAT活性的硫基自由基。第一个SET是从7，7 ′-OMe-TPA的富电子萘基到质子化的N-杂芳环，第二个SET是从7，7 ′-OMe-TPA的硫代磷酸部分到所产生的萘基自由基阳离子。光谱研究和理论计算的特点stepwiseSET过程介导的短寿命的中间体。将该催化体系应用于四种不同的碳氢（C-H）官能化反应，即N-杂环芳烃的羟烷基化和烷基化反应、醇的无受体脱氢反应和亚胺的苄基化反应，并对反应中的官能团进行了高容忍度的研究。
We developed organocatalyst systems to promote the cleavage ofstable C-H bonds, such as formyl,alpha-hydroxy, and benzylic C-H bonds, through ahydrogen atom transfer (HAT) process without the use of exogenous photo-sensitizers. An electronically tuned thiophosphoric acid, 7,7'-OMe-TPA, wasassembled with substrate or co-catalystN-heteroaromatics through hydrogen bondingand pi-pi interactions to form electron donor-acceptor (EDA) complexes.Photoirradiation of the EDA complex induced stepwise, sequential single-electrontransfer (SET) processes to generate a HAT-active thiyl radical. Thefirst SET wasfrom the electron-rich naphthyl group of 7,7'-OMe-TPA to the protonatedN-heteroaromatics and the second proton-coupled SET (PCET) from thethiophosphoric acid moiety of 7,7'-OMe-TPA to the resulting naphthyl radicalcation. Spectroscopic studies and theoretical calculations characterized the stepwiseSET process mediated by short-lived intermediates. This organocatalytic HAT systemwas applied to four different carbon-hydrogen (C-H) functionalization reactions,hydroxyalkylation and alkylation ofN-heteroaromatics, acceptorless dehydrogenation of alcohols, and benzylation of imines, withhigh functional group tolerance.