. "; R3 is an alkyl group selected from n-propyl or i-propyl, wherein one carbon atom is optionally replaced by O and wherein said alkyl group is optionally independently substituted with an oxo group and/or phenyl or morpholinyl; or Rb is phenyl, methoxy, phenoxy, fluoro, chloro or oxo; R3 is a hydrogen, methyl, ethyl, n-propyl, n-butyl, i-butyl, methoxymethyl, methylthiomethyl, propenyl, butenyl, i" . . .