Characterization and Monitoring of Transient Enamine Radical Intermediates in Photoredox/Chiral Primary Amine Synergistic Catalytic Cycle
Shixue Zhang, Liang Cheng, Jianqing Qi, Zongbin Jia, Long Zhang, Lei Jiao, Xingwei Guo, Sanzhong Luo
Abstract
Open AccessCCS ChemistryCOMMUNICATIONS28 Mar 2024Characterization and Monitoring of Transient Enamine Radical Intermediates in Photoredox/Chiral Primary Amine Synergistic Catalysis Cycle Shixue Zhang, Liang Cheng, Jian-Qing Qi, Zongbin Jia, Long Zhang, Lei Jiao, Xingwei Guo and Sanzhong Luo Shixue Zhang , Liang Cheng , Jian-Qing Qi , Zongbin Jia , Long Zhang , Lei Jiao , Xingwei Guo and Sanzhong Luo https://doi.org/10.31635/ccschem.024.202404035 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Enamine-derived radicals are crucial intermediates in singly occupied molecular orbital (SOMO) catalysis. However, observing them directly is elusive and remains a long-standing challenge. Here, an advanced time-resolved electron paramagnetic resonance technique is employed to characterize and monitor the key intermediates in photoredox transformations by primary aminocatalysis on a microsecond timescale. The transient enamine radical cation, generated by single electron transfer (SET), and the deprotonated form α-imino radical intermediates, were directly observed for the first time, both spectroscopically and kinetically. When reacting with styrene, enamine radical cation was found to be faster than α-imino radical by one order of magnitude. This reveals the subtle role of deprotonation associated with secondary enamine radical cation in the photoredox transformations by primary aminocatalysis. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2024 Chinese Chemical Society Downloaded 0 times PDF downloadLoading ...