By reduction of 2-propoxybenzamidoxime (I) with H2 over Raney-Ni in ethanol to give 2-propoxybenzamidine (II), m.p. 170-1 C, which was condensed with ethyl alpha-nitrosocyanacetate (A) by means of sodium methoxide in methanol yielding 4-amino-2-(2-propoxyphenyl)-5-nitrosopyrimid-6-one (III), m.p. 215-6 C. This compound was reduced with sodium dithionite in water to give 4,5-diamino-2-(2-propoxyphenyl)- pyrimid-6-one (IV), m.p. 162-4 C, which was finally cyclized with sodium nitrite in aqueous HCl.