A facile and practical solid-phase synthesis of trisubstituted 2-aminoimidazolones

The solid-phase synthesis of trisubstituted 2-aminoimidazolones based on the intramolecular cyclization between a δ-guanidinium nitrogen and the amide carbonyl under acidic conditions is described. The method utilizes easily accessible commercial starting materials, mild reaction conditions, as well as a cyclizative–cleavage strategy to afford the desired products in moderate to good overall yields and good to excellent purity.