2-[(2-ethoxy-5(4-ethylpiperazine-1-sulphonyl)phenyl)]-7-ethoxycarbonyl-5-methylimidazo[5,1-f][1,2,4]triazin-4(3H)-one is a reagent in the preparation of imidazotriazinones which functions as substrates in the synthesis of phosphodiesterase 5 inhibitors.