The product is prepared by condensation of 3-[3-(1-piperidinylmethyl)phenoxy]propylamine (I) with 1-amino-2-methoxy-1-cyclobutene-3,4-dione (II) in methanol, followed by treatment with HCl.
Treatment of 3-amino-4-[3-(3-piperidinomethylphenoxy)propylamino]-1,2,5-thiadiazole-1-oxide, BMY-25260 (I), with an excess of hydrogen chloride in methanol gives N-[3-(3-piperidinomethylphenoxy)propyl]ethanediimidamide trihydrochloride (II) in high yield. Compound (II) is then treated (method A) with sulfur monochloride or sulfur dichloride in DMF, or alternatively (method B) with N,N'-thiobisphthalimide and triethylamine in methylene chloride, followed by treatment with HCl.