Author
Na Chen
Bio: Na Chen is an academic researcher from Huaqiao University. The author has contributed to research in topics: Radical & Alkene. The author has an hindex of 2, co-authored 2 publications receiving 22 citations.
Papers
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01 May 2021
TL;DR: In this article, a review of recent advances in the chemistry of electrochemically generated nitrogen-centered radicals (NCRs) is presented, based on the electrochemical strategies for their formation and the types of NCRs.
Abstract: There is a resurgence of interests in organic electrochemistry, which is generally accepted as a green synthetic tool. In this context, many electrochemical methods have been developed in the past decade to access various nitrogen-centered radicals (NCRs) from readily available precursors in a controlled fashion, enabling the rapid development of many NCR-mediated new reactions for the construction of nitrogen-containing organic compounds. In this review, recent advances in the chemistry of electrochemically generated NCRs are critically highlighted, based on the electrochemical strategies for their formation and the types of NCRs. Focus is put on the mechanism for the electrochemical generation of different NCRs and their synthetic applications.
100 citations
TL;DR: In this article, various radical species such as alkene and arene radical cations and carbon-and heteroatom-centered radicals are generated from readily available precursors through direct electrolysis, molecular electrocatalysis or molecular electrophotocatalysis.
Abstract: Organic radicals are versatile synthetic intermediates that provide reactivities and selectivities complementary to ionic species. Despite its long history, electrochemically driven radical reactions remain limited in scope. In the past few years, there have been dramatic increase in research activity in organic electrochemistry. We have been developing electrochemical and electrophotocatalytic methods for the generation and synthetic utilization of organic radicals. In our studies, various radical species such as alkene and arene radical cations and carbon- and heteroatom-centered radicals are generated from readily available precursors through direct electrolysis, molecular electrocatalysis or molecular electrophotocatalysis. These radical species undergo various inter- and intramolecular oxidative transformations to rapidly increase molecular complexity. The simultaneous occurrence of anodic oxidation and cathodic proton reduction allows the oxidative reactions to proceed through H2 evolution without external chemical oxidants.
40 citations
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TL;DR: The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding of these reactive species increases as discussed by the authors , which is demonstrated in the recent advances in C-H amination and the (di)amination of alkenes.
Abstract: The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding of these reactive species increases. The utility of these reactive intermediates is demonstrated in the recent advances in C-H amination and the (di)amination of alkenes. Synthesis of previously challenging structures can be achieved by efficient functionalization of sp2 moieties without prefunctionalization, allowing for faster and more streamlined synthesis. This Review addresses the generation, reactivity, and application of NCRs, including, but not limited to, iminyl, aminyl, amidyl, and aminium species. Contributions from early discovery up to the most recent examples have been highlighted, covering radical initiation, thermolysis, photolysis, and, more recently, photoredox catalysis. Radical-mediated intermolecular amination of (hetero)arenes can occur with a variety of complex amine precursors, generating aniline derivatives, an important class of structures for drug discovery and development. Functionalization of olefins is achievable in high anti-Markovnikov regioselectivity and allows access to difunctionalized structures when the intermediate carbon radicals are trapped. Additionally, the reactivity of NCRs can be harnessed for the rapid construction of N-heterocycles such as pyrrolidines, phenanthridines, quinoxalines, and quinazolinones.
66 citations
TL;DR: In this article, a novel and efficient electrochemical initiated radical strategy was developed for the preparation of both N-substituted and N-unsubstantituted 4-selanyl isoquinolin-1(2H)-ones through selenylation of isoquinol-1 (2H) with organodiselenides under chemical oxidant-, additive-free and ambient conditions.
48 citations
TL;DR: In this paper , a novel and efficient electrochemical initiated radical strategy was developed for the preparation of both N-substituted and N-unsubstantituted 4-selanyl isoquinolin-1(2H)-ones through selenylation of isoquinol-1 (2H) with organodiselenides under chemical oxidant-, additive-free and ambient conditions.
46 citations
TL;DR: In this article, an electrochemical palladium-catalyzed oxidative carbonylation of arylhydrazines with alkynes was proposed, which is regarded as an alternative supplement of the carbonylative Sonogashira reaction.
Abstract: Oxidative carbonylation using carbon monoxide has evolved as an attractive tool to valuable carbonyl-containing compounds, while mixing CO with a stoichiometric amount of a chemical oxidant especially oxygen is hazardous and limits its application in scale-up synthesis. By employing anodic oxidation, we developed an electrochemical palladium-catalyzed oxidative carbonylation of arylhydrazines with alkynes, which is regarded as an alternative supplement of the carbonylative Sonogashira reaction. Combining an undivided cell with constant current mode, oxygen-free conditions avoids the explosion hazard of CO. A diversity of ynones are efficiently obtained using accessible arylhydrazines and alkynes under copper-free conditions. A possible mechanism of the electrochemical Pd(0)/Pd(II) cycle is rationalized based upon cyclic voltammetry, kinetic studies, and intermediates experiments.
40 citations
TL;DR: In this article , the most recent contributions are reviewed, demonstrating exciting new opportunities, namely, the combination of PEC with other reactivity paradigms (hydrogen-atom transfer, radical polar crossover, energy transfer sensitization), scalability up to multigram scale, novel selectivities in SET super-oxidations/reductions and the importance of precomplexation to temporally enable excited radical ion catalysis.
Abstract: Synthetic photoelectrochemistry (PEC) is receiving increasing attention as a new frontier for the generation and handling of reactive intermediates. PEC permits selective single-electron transfer (SET) reactions in a much greener way and broadens the redox window of possible transformations. Herein, the most recent contributions are reviewed, demonstrating exciting new opportunities, namely, the combination of PEC with other reactivity paradigms (hydrogen-atom transfer, radical polar crossover, energy transfer sensitization), scalability up to multigram scale, novel selectivities in SET super-oxidations/reductions and the importance of precomplexation to temporally enable excited radical ion catalysis.
37 citations