~tBuONa/DMSO/air Mediated C-O Bond Cleavage Of Model Lignin Compounds And C-O Bond Construction

In recent years,the depolymerization of macromolecular lignin into small molecular aromatic compounds has attracted the attention of many researchers.However,the structure of lignin is complex,and the lignin composition of different samples is different,so it is difficult to obtain consistent reaction data when lignin is used as the actual reactant.In this case,using lignin model compounds is preferable to using lignin itself.The purpose of depolymerizing lignin is achieved by biological or chemical cleavage of specific chemical bonds of lignin model compounds.Among chemical methods,most of the cracking methods focus on the use of high temperature,high pressure,expensive metal catalysts,etc.Therefore,it is indispensable to develop a mild and green method to crack lignin model compounds.This paper mainly discusses from the following two aspects:1.Under the ~tBu ONa-DMSO-air system,without using transition metal catalyst,the small molecule compound(phenoxyethylbenzene)containingβ-O-4 type C-O bond was cracked,the conversion rate of the raw material was more than 99%,and the yield of styrene and phenol reached 91%and 82%respectively.The reaction has good functional group tolerance,and the derivatives of styrene and phenol can be obtained in high yields.At the same time,for different kinds of substrates,such as alkyl ethers,aryl ethers,esters,2,3-dihydrobenzofuran,etc.,C-O bond cleavage can be achieved,and the target products can be obtained in high yields.2.Under the same system,we realized a series reaction with benzyl alcohol and benzaldehyde to form styrene-anisole and construct C-O bond efficiently.This reaction also does not require transition metal catalysis,and does not require other additives,can occur under mild conditions,and the yield is well.