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1. (WO1999006407) THERAPEUTICALLY ACTIVE 1,2,4-TRIAZOLO(4.,3-b) PYRIDAZINE DERIVATIVES AS LIGANDS FOR GABA RECEPTORS

Pub. No.:    WO/1999/006407    International Application No.:    PCT/GB1998/002227
Publication Date: Fri Feb 12 00:59:59 CET 1999 International Filing Date: Tue Jul 28 01:59:59 CEST 1998
IPC: C07D 487/04
Applicants: MERCK SHARP & DOHME LIMITED
CARLING, William, Robert
MOORE, Kevin, William
REEVE, Austin, John
Inventors: CARLING, William, Robert
MOORE, Kevin, William
REEVE, Austin, John
Title: THERAPEUTICALLY ACTIVE 1,2,4-TRIAZOLO(4.,3-b) PYRIDAZINE DERIVATIVES AS LIGANDS FOR GABA RECEPTORS
Abstract:
The invention provides a novel class of compounds (1,2,4-triazolo[4.3-b] pyridazine derivatives) which are ligands for GABAA receptors containing the α5 subunit, and which satisfy formula (I) wherein R?1 and R2¿ are hydrogen or defined substituents; X is a 5-membered ring containing 1,2,3 or 4 heteroatoms independently chosen from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur, or a 6-membered heteroaromatic ring containing 1,2 or 3 nitrogen atoms, the 5- or 6-membered heteroaromatic ring optionally being fused to a benzene ring and optionally being substituted; or X is optionally substituted phenyl; Y is optionally branched C¿1-4?alkylene optionally substituted by an oxo group or Y is a group (CH2)jO wherein the oxygen atom is nearest to group X and j is 2, 3 or 4; and Z is optionally substituted furyl, thienyl or pyridyl; which compounds are useful in the treatment of dementing illness such as Alzheimer's disease.