摘要 |
The present invention provides a compound of formula (I) wherein A is an optionally substituted C<SUB>1-4</SUB>alkylidene group or a bond, R<SUP>20 </SUP>and R<SUP>21 </SUP>are hydrogen, alkyl groups or heterocyclic groups, R<SUP>1 </SUP>and R<SUP>2 </SUP>are small substituents or hydrogen, L is O, S or substituted N, X is a 5- or 6-membered heteroaromatic ring, Y is C<SUB>1-4</SUB>alkylidene and Z is a 5- or 6-membered heteroaromatic ring; or a pharmaceutically acceptable salt thereof; pharmaceutical compositions comprising it; its use in therapy; its use in making medicaments for treating neurodegenerative disease and methods of using it to enhance cognition.
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