The present invention is concerned with aryl-isoxazol-4-yl-imidazo[1,5-a]pyridine derivatives of formula (I) wherein: R is hydrogen, halogen, hydroxy, lower alkyl, benzyloxy or -O-(CH)-(CO)-5 or 6 membered heteroaryl optionally substituted by aryl and lower alkyl； R is hydrogen, lower alkyl, or -(CO)-R； R is hydrogen, halogen, cyano, lower alkyl, or -(CO)-R； R is hydroxy, lower alkoxy, NR'R'', wherein R' and R'' are each independently hydrogen, cycloalkyl, 5 or 6-membered heterocycloalkyl or lower alkyl optionally substituted by cycloalkyl, cyano, 5 or 6-membered heterocycloalkyl or 5 or 6-membered heteroaryl； as well as pharmaceutically acceptable acid addition salts thereof. It has been found that this class of compounds show high affinity and selectivity for GABA A α5 receptor binding sites and might be useful as cognitive enhancer or for the treatment of cognitive disorders like Alzheimer's disease.
