Visible-Light-Induced Multicomponent Synthesis of Tetrasubstituted Imidazoles

An efficient visible light photocatalyzed one-pot, three-component synthesis of tetrasubstituted imidazoles was developed. Catalytic amount of 2,4-dinitrophenol (2,4-DNP) was necessary for the successful coupling of anilines, aldehydes and alpha-keto vinyl azides to yield imidazoles in the presence of 7 W blue LED light. The scope of the reaction was demonstrated by synthesizing a series of highly functionalized imidazoles in excellent yields (75-86%). Control experiments were carried out and a mechanistic rationalization of the three-component reaction was proposed.