Redox-neutral photocatalytic strategy for selective C–C bond cleavage of lignin and lignin models via PCET process

作     者：Yinling Wang Yue Liu Jianghua He Yuetao Zhang 

作者机构：State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University 

出 版 物：《Science Bulletin》 (科学通报（英文版）)

年 卷 期：2019年第64卷第22期

页      面：1658-1666页

核心收录：

学科分类：07[理学] 070303[理学-有机化学] 0703[理学-化学] 

基　　金：supported by the National Natural Science Foundation of China (21975102  21871107  21774042  and 21422401) 

主　　题：C–C bond cleavage Lignin depolymerization Photocatalysis Proton-coupled electron transfer Redox-neutral 

摘      要：It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and selectivity.We have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/mol.Without breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and selectivities.Preliminary studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.