Cyclization of 2-ethoxybenzamidine (I) with 2-butyramidopropionic acid (II) and ethoxalyl chloride (III) by means of DMAP in refluxing pyridine gives 2-(2-ethoxyphenyl)-5-methyl-7-propyl-3,4-dihydroimidazo[5,1-f][1,2,4]triazin-4-one (IV), which is sulfonated with chlorosulfonic acid to provide the sulfonyl chloride (V). Finally, this compound is condensed with 1-ethylpiperazine (VI) in dichloromethane.