[Acc. Chem. Res.] 我室徐海超教授发表论文:Chemistry with Electrochemically Generated N-Centered Radicals

2019年12月02日

我室徐海超教授在 Acc. Chem. Res. 上发表论文:Chemistry with Electrochemically Generated N-Centered Radicals

文章链接:https://pubs.acs.org/doi/10.1021/acs.accounts.9b00472

摘要:

N-centered radicals are versatile reaction intermediates that can react with various π systems to construct C–N bonds. Current methods for generating N-centered radicals usually involve the cleavage of an N–heteroatom bond; however, similar strategies that are applicable to N–H bonds prove to be more challenging to develop and therefore are attracting increasing attention.

In this Account, we summarize our recent efforts in the development of electrochemical methods for the generation and synthetic utilization of N-centered radicals. In our studies, N-aryl amidyl radical, amidinyl radical and iminyl radical cation intermediates are generated from N–H precursors through direct electrolysis or indirect electrolysis assisted by a redox catalyst. In addition, an electrocatalytic method that converts oximes to iminoxyl radicals has also been developed. The electrophilic amidyl radical intermediates can participate in 5-exo or 6-exo cyclization with alkenes and alkynes to afford C-centered radicals, which can then undergo various transformations such as H atom abstraction, single-electron transfer oxidation to a carbocation, cyclization, or aromatic substitution, leading to a diverse range of N-heterocyclic products. Furthermore, amidinyl radicals, iminyl radical cations, and iminoxyl radicals can undergo intramolecular aromatic substitution to afford various N-heteroaromatic compounds. Importantly, the electrochemical reaction can be channeled toward a specific product despite the presence of other competing pathways. For a successful electrosynthesis, it is important to take into consideration of both the electron transfer steps associated with the electrode and the nonelectrode related processes.