abstract |
The present invention provides a compound which has the effect of blocking PDE, and which is useful as a medicament for the prevention or treatment of schizophrenia or so. A compound of formula (I0): wherein R1 represents a substituent, R2 represents a hydrogen atom, or a substituent R3 represents a hydrogen atom, or a substituent, Ring A represents an aromatic ring which may be substituted by B, ring, which may be substituted, or a salt thereof. |