Arylethanolamines in Ritter reaction: Synthesis of 2,4‐Diarylimidazole Core

Abstract

AbstractA three‐step synthesis of imidazole core from arylethanolamines was achieved. A key to this sequence is a Ritter reaction of arylethanolamines promoted by perchloric acid, allowing the formation of 2‐methylamino‐1‐(acylamino)‐1‐arylethanes in 33–82% yields. The latter were subjected to thermal cyclization into 4‐arylimidazolines by simple heating in n‐butanol in 51–95% yields or to one‐pot cyclization‐oxidation sequence to produce 2,4‐diarylimidazoles in 73–93% yields. The efficiency of this approach was demonstrated on a straightforward one‐pot synthesis of 2,4‐diarylimidazoles from readily available starting materials: aromatic aldehydes, sarcosine, paraformaldehyde and benzonitriles, in 42–49% total yields.