The invention relates to a compound of formula (I)
wherein A and R
1
to R
3
are defined as in the description and in the claims. The compound of formula (I) can be used as a medicament.
The present invention aims to provide a compound having a PDE inhibitory action and useful as a medicament for the prophylaxis or treatment of schizophrenia and the like.
A compound represented by the formula (1
x
):
wherein each symbol is as described in the DESCRIPTION, or the formula (1):
W
1
—W
2
(1)
wherein each symbol is as described in the DESCRIPTION,
or a salt thereof.