The present invention provides compounds of formula I:
1
in which:
one of X and Y is a nitrogen atom substituted by a group R
6
′ and the other is a carbon atom substituted by an isoxazole group substituted on its carbon atoms by groups R
3
and R
4
;
one of R
6
and R
6
′ is hydrogen;
either all of W
1
, W
2
, W
3
and W
4
are carbon or one of W
1
, W
2
, W
3
and W
4
is nitrogen and the rest are carbon;
and R
1
and R
2
are, independently, a small group, heteroaromatic ring or a 4-7 membered cyclic amine ring; processes for making them; pharmaceutical composition containing them; their use in therapy, particularly for enhancing cognition in conditions such as Alzheimer's Disease; and methods of treatment using them.