Recent Progress in Benzylic C(sp3)-H Functionalization of Toluene and Its Derivatives

Toluene derivatives are alkyl aromatic hydrocarbons derived from oil and natural gas and are among the cheapest and most readily available materials for the chemical industry. C-H functionalization is important for the synthesis of various bioactive substances, and inert benzylic hydrocarbon bond activation has long been a big challenge in this field due to the high hydrocarbon bond energy. Therefore, the development of simple and efficient methods for C-C and C-X bonds formation has been demonstrated as one of the hot topics by activating the benzylic C(sp(3))-H bonds in recent years. The progress in benzylic C(sp(3))-H functionalization of toluene and its derivatives under different catalytic conditions in the past decade is summarized according to different reaction classifications. The reaction substrate compatibility, mechanism, applications, advantages and limitations in this field are also discussed in detail.