Characterization and Monitoring of Transient Enamine Radical Intermediates in Photoredox/Chiral Primary Amine Synergistic Catalytic Cycle  

作　　者：Shixue Zhang Liang Cheng Jian-Qing Qi Zongbin Jia Long Zhang Lei Jiao Xingwei Guo Sanzhong Luo 

机构地区：[1]Center of Basic Molecular Science(CBMS),Department of Chemistry,Tsinghua University,Beijing 100084

出　　处：《CCS Chemistry》2024年第10期2420-2426,共7页中国化学会会刊（英文）

基　　金：provided by the Tsinghua University Dushi Program,China,the National Natural Science Foundation of China(grant nos.22031006,22193011,22373056,and 22393891);the Haihe Laboratory of Sustainable Chemical Transformations,China,and the National Science&Technology Fundamental Resource Investigation Program of China(grant no.2023YFA1500008).

摘　　要：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 was 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 ofα-imino radical intermediates were directly observed for the first time,both spectroscopically and kinetically.In reactions with styrene,enamine radical cation was found to be faster thanα-imino radical by one order of magnitude.This revealed the subtle role of deprotonation associated with secondary enamine radical cation in the photoredox transformations by primary aminocatalysis.

关 键 词：AMINOCATALYSIS radical chemistry electron paramagnetic resonance direct observation time-resolved technique 

分 类 号：O62[理学—有机化学]