1) By methanolysis of 2,6-dichlorophenylacetonitrile (I) by means of H2SO4 to methyl 2,6-dichlorophenylacetate (II), which is then condensed with guanidine (A) in isopropanol. 2) By condensation of S-methylisothiourea (V) with 2,6-dichlorophenylacetyl chloride (VI) in acetone to afford S-methyl-N-(2,6-dichlorophenylacetyl)isothiourea (VII); this product is then treated with ammonia in isopropanol. 3) By condensation of 2,6-dichlorophenylacetic acid (VIII) with guanidine (A) in toluene.
4) By reaction of the nitrile (I) with ethyl formate (B) by means of NaOEt in ethanol to give alpha-formyl-2,6-dichlorophenylacetonitrile (III), which is condensed with guanidine hydrochloride (A) by means of NaOEt in ethanol to yield alpha-(guanidinomethylene)-2,6-dichlorophenylacetonitrile (IV); this product is finally hydrolyzed and rearranged by means of HCl.