Peroxide: A Novel Methylating Reagent

Methylation is an important transformation in organic chemistry. Methods for methylation in industry and academia still frequently employ hazardous and toxic reagents, such as diazomethane, dimethyl carbonate, methyl iodide, and dimethyl sulfate. From the point of view of sustainable and environmentally friendly chemistry, much effort has been devoted to the discovery and development of alternative methylating reagents. A particularly attractive new methyl source that is attracting attention is derived from the cleavage of peroxides. This short review summarizes recent important developments using peroxides as versatile methylating reagents, including direct methylation and sequential methylation together with other functionalization processes. The corresponding reaction mechanisms are also discussed. 1 Introduction 2 Direct Methylation 2.1 Methylation of C–H Bonds 2.2 Methylation of N–H Bonds 2.3 Methylation of O–H Bonds 3 Methylation together with Other Functionalizations 3.1 Oxidation and Methylation 3.2 Decarboxylative Methylation 3.3 Methylation and Cyclization 4 Conclusions and Perspectives