Light-induced, metal free, and green synthetic approach for N-methylation via coupling of benzylamine, benzaldehyde and CO2 at atmospheric pressure

Herein, we report a combination of experimental and computational studies for the photochemical synthesis of N,N’-dibenzyl-N-methylamine via three component coupling of benzylamine, benzaldehyde, and CO₂ assisted by 1-butyl-3-methylimidazolium chloride ionic liquid at atmospheric pressure. The theoretical investigation revealed the formation of imine and two reaction intermediates (I & II) through the coupling reaction of CO₂ with benzaldehyde and benzylamine in excess phenyl saline. The Molecular electrostatic potential and activation energy calculations depicted the formation of Intermediate I (formoxysilane) formation by inserting CO₂ into the SiH bond of the phenyl silane via hydrogen bonding. Furthermore, Intermediate I converted to Intermediate II by reacting with phenyl saline (PhSiH₃) and imine, followed by the final methylated product via the CN bond between the carbon of CO₂ and nitrogen of the imine group.