© Schweizerische Chemische Gesellschaft. A simple transition metal-free procedure using formaldehyde for the N,N-dimethylation and N-methylation of primary and secondary anilines is reported. The reaction showed limitations on sterically hindered and electron-withdrawing anilines, but is successful on amines with electron-donating substituents. Formaldehyde acts as both the reducing agent and the carbon source in the reaction.
Man, N., Li, W., Stewart, S., & Wu, X. F. (2015). Transition metal-free methylation of amines with formaldehyde as the reductant and methyl source. Chimia, 69(6), 345-347. https://doi.org/10.2533/chimia.2015.345