The compounds of formula (I) wherein R1, R2, R21, R22, R23, R24, Y and R3 have the meanings as given in the description, the salts thereof, and the stereoisomers of the compounds and the salts thereof are effective inhibitors of the type 5 phosphodiesterase.
式(I)中的化合物,其中R1、R2、R21、
R22、R23、R24、Y和R3的含义如描述中所述,其盐以及这些化合物和其盐的立体异构体是有效的第5型
磷酸二酯酶抑制剂。