Disclosed are selective phosphodiesterase inhibitor compounds shown informula (I) for treating Erectile Dysfunction, the pharmaceutically acceptablesaltsand configurational isomers thereof In the formula, the substituents R1, R2,R3, R4and R5 are defined as in the specification. Also disclosed are a method forpreparingcompounds of formula (I), a medical composition comprising compounds offormula (I), and the use of these compounds for preparing a drug treating orpreventing male Erectile Dysfunction.
