The invention provides for a compound of formula (I) or a pharmaceutically
acceptable salt thereof:
wherein R.sup.1, R.sup.2, R.sup.3, A, B, D, m, n, x, and y are defined as
described in the specification. The invention additionally provides a
pharmaceutically composition comprising the compound of formula I,
together with a method of using the same to treat or prevent neurological
and psychiatric disorders. The compounds are useful in therapy related to
the treatment or prevention of mGluR2 receptor-mediated disorders.