Recent Development in Synthesis of N‐methylamines with Amines and Methanol

The N-methylation reaction of amines with methanol via the borrowing-hydrogen strategy is an important method for the construction of C-N bonds. Compared with other C1 sources, such as toxic formaldehyde or expensive formic acid, methanol is more suitable for N-methylation reactions due to its eco-friendliness and low price. Using this strategy, various types N-methylated products, including biological and pharmaceutical molecules have been prepared. Here, we present a thorough survey of decades of articles showing current developments in N-methylation reactions with methanol. We discuss homogenous, heterogenous and light-driven catalytic systems for both N-methylation and N,N-dimethylation reactions. This review presents the shortcomings of current developments and provides future development progress in N-methylation reactions with methanol.