Photochemical reaction mechanism of benzophenone protected guanosine at N7 position  

作　　者：Yan Guo Hongtao Bian Le Yu Jiani Ma Yu Fang 

机构地区：[1]Key Laboratory of Applied Surface and Colloid Chemistry,Ministry of Education,School of Chemistry and Chemical Engineering,Shaanxi Normal University,Xi’an 710119,China [2]Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education,College of Chemistry and Materials Science,Northwest University,Xi’an 710127,China

出　　处：《Chinese Chemical Letters》2025年第3期311-315,共5页中国化学快报(英文版)

基　　金：sponsored by grants from the National Natural Science Foundation of China(Nos.22322301,22303046);the Shaanxi Science Fund for Distinguished Young Scholars(No.2021JC-38);the Fundamental Research Funds for the Central Universities(Nos.GK202207001,GK202304008);the Shaanxi Province Postdoctoral Science Foundation(No.2023BSHEDZZ187).

摘　　要：Aryl ketones as photolabile protecting group(PPG)to modify purine imines is a novel nucleic acid protection strategy.Especially,photoprotection of N7-guanosine is the first reported photoprotected nucleoside that can affect the Hoogsteen recognition site of guanosine.However,the mechanism,which is pivotal to high efficiency of photorelease and applications of PPGs in biological and medical systems,is unclear.Here,a detailed deprotection mechanism of benzophenone protected guanosine(BP-Guo)at N7 position is reported.Upon irradiation,BP-Guo populates to singlet state,which generates^(3)[BP]-Guo via intersystem crossing process.Thereafter,triplet energy transfer competes with hydrogen atom transfer forming BP-^(3)[Guo]and ketyl-Guo,respectively.Both species break C–N bond to release guanosine.These results provide deeper insights into exploiting improved strategies for photo-protecting nucleic acids.In particular,the TTET pathway could trigger well-known cyclization reactions that brings about DNA mutagenic adducts.The latter should be avoided in developing improved strategies for photoprotecting nucleic acids.

关 键 词：Excited state Photolabile protecting group Time-resolved spectroscopy Transient absorption DFT calculation 

分 类 号：O621.1[理学—有机化学]