By cyclization of 5-diazoimidazole-4-carboxamide (I) with 2-chloroethyl isocyanate (II) in dichloromethane.
By reaction of 5-diazoimidazole-4-carboxamide (II), prepared by diazotization of 5-aminoimidazole-4-carboxamide (I) with nitrous acid, with methylisocyanate (III) either alone or in dichloromethane.