| abstract |
The present invention provides a compound with PDE inhibitory effect, which is suitable as a drug for preventing or treating schizophrenia and the like. A compound of formula (I 0 ), or a salt thereof: wherein R 1 represents a substituent; R 2 represents a hydrogen atom or a substituent; R 3 represents a hydrogen atom or a substituent; Ring A represents an aromatic ring that may be substituted; and Ring B represents a 5-membered heteroaromatic ring which may be substituted. |