8-QUINOLINXANTHINE AND 8-ISOQUINOLINXANTHINE DERIVATIVES AS PDE 5 INHIBITORS

A compound of formula (I) in free or salt form, where R is hydrogen or alkyl optionally substituted by hydroxy, alkoxy, or alkylthio, R is hydrogen, alkyl, hydroxyalkyl, alkylcarbonyloxyalkyl, alkoxyalkyl, alkylthioalkyl, alkenyl, cycloalkylalkyl, heterocyclylalkyl, aralkyl in which the aryl ring thereof is optionally fused to a 5-membered heterocyclic group or is optionally substituted by one or more substituents selected from alkoxy, amino, alkylamino, dialkylamino, acylamino, halogen, hydroxy, aminosulfonyl, alkylaminosulfonyl, dialkylaminosulfonyl, alkylsulfonylamino or dialkylaminosulfonylamino, R is hydrogen or alkyl optionally substituted by hydroxy, alkoxy, or alkylthio, R is hydrogen or alkyl, R is a quinolinyl, isoquinolinyl or oxodihydroisoquinolinyl group optionally fused to a 5-membered heterocyclic group and optionally substituted by one or more substituents selected from halogen, cyano, hydroxy, alkyl, hydroxyalkyl, alkoxyalkyl, alkylthioalkyl, alkoxy, alkylthio, alkenyl, alkoxycarbonyl, alkynyl, carboxyl, acyl, a group of formula -N(R )R , aryl optionally substituted by one or more substituents selected from halogen or alkoxy, or heteroaryl having 5 or 6 ring atoms attached through a ring carbon atom to the indicated carbon atom, and R and R are each independently hydrogen or alkyl optionally substituted by hydroxy or alkoxy or one of R and R is hydrogen and the other is acyl, or R and R together with the nitrogen atom to which they are attached denote a 5- or 6-membered heterocyclyl group.