Aspects of the present invention are directed towards compounds of Formula I for the treatment of human erectile disorders including erectile dysfunction in men. wherein: R1 is hydrogen, halo, hydroxy, nitro, cyano, phenyl, trifluoromethyl, C1-C6 alkyl, C1-C6 alkoxy, carboxy, amino, cyclohexyl, C1-C6 alkylamino, or (C1-C6 alkyl)2amino; R2 is hydrogen, halo, hydroxy, nitro, cyano, trifluoromethyl, C1-C6 alkyl, C1-C6 alkoxy, carboxy, amino, C1-C6 alkylamino, or (C1-C6 alkyl)2amino; R3 is a group of the formula R4 is hydrogen or C1-C6 alkyl; R5 is hydrogen, halo, hydroxy, nitro, cyano, phenyl, trifluoromethyl, C1-C6 alkyl, C1-C6 alkoxy, carboxy, amino, C1-C6 alkylamino, or (C1-C6 alkyl)2amino; and R6 is hydrogen, halo, hydroxy, nitro, cyano, trifluoromethyl, C1-C6 alkyl, C1-C6 alkoxy, carboxy, amino, C1-C6 alkylamino, or (C1-C6 alkyl)2amino; or pharmaceutically acceptable salts thereof