The reaction of S-methyl isothiouronium iodide (I) with n-hexyl isocyanate (II) by means of triethylamine in acetone gives N-(methylthioiminocarbonyl)-N?n-hexylurea (III), which is then condensed with 1,4-bis(3-aminopropyl)piperazine (IV) in refluxing isopropanol and methanesulfonic acid.