Design and synthesis of novel 5-(3,4,5-trimethoxybenzoyl)-4-aminopyrimidine derivatives as potent and selective phosphodiesterase 5 inhibitors: scaffold hopping using a pseudo-ring by intramolecular hydrogen bond formation.

5-(3,4,5-Trimethoxybenzoyl)-4-amimopyrimidine derivatives were found as a novel chemical class of potent and highly selective phosphodiesterase 5 inhibitors. A pseudo-ring formed by an intramolecular hydrogen bond constrained the conformation of 3-chloro-4-methoxybenzylamino and 3,4,5-trimethoxybenzoyl substituents and led to the discovery of T-6932 (19a) with a potent PDE5 inhibitory activity (IC50 = 0.13 nM) and a high selectivity over PDE6 (IC50 ratio: PDE6/PDE5 = 2400). Further modification at the 2-position of T-6932 resulted in the finding of 26, which exhibited potent relaxant effects on isolated rabbit corpus cavernosum (EC30 = 11 nM) with a high PDE5 selectivity over PDE6 (IC50 ratio: PDE6/PDE5 = 2800).

The discovery of avanafil for the treatment of erectile dysfunction: a novel pyrimidine-5-carboxamide derivative as a potent and highly selective phosphodiesterase 5 inhibitor.

Novel pyrimidine-5-carboxamide derivatives bearing a 3-chloro-4-methoxybenzylamino group at the 4-position were identified as potent and highly selective phosphodiesterase 5 inhibitors. Among them, we successfully found 10j (avanafil) which exhibited a potent relaxant effect on isolated rabbit cavernosum (EC30=2.1 nM) and a high isozyme selectivity.