The reaction ot S-(2-aminothiazol-4-ylmethyl)isothiourea (I) with 3-chloropropionitrile (II) by means of NaOH in ethanol - water gives 3-(2-aminothiazol-4-ylmethylthio)propionitrile (III), which is condensed with benzoyl isothiocyanate (IV) in refluxing acetone to afford 3-[2-(3-benzoylthioureido)thiazol-4-ylmethylthio]propionitrile (V). The hydrolysis of (V) with K2CO3 in acetone - methanol - water yields 3-(2-thioureidothiazonl-4-ylmethylthio)propionitrile (VI), which by methylation with methyl iodide in refluxing ethanol is converted into 3-[2-(S-methylisothioureido)thiazol-4-ylmethylthio]propionitrile hydroiodide (VII). The reaction of (VII) with NH3 and NH4Cl in methanol at 90 C in a pressure vessel affords 3-(2-guanidinothiazol-4-ylmethylthio)propionitrile (VIII), which by partial alcoholysis with methanol by means of dry HCl in CHCl3 is converted into methyl 3-(2-guanidinothiazol-4-ylmethylthio)propionimidate (IX). Finally, this compound is treated with sulfamide in refluxing methanol.