| 摘要 |
The present invention relates to compounds of formula (I) wherein R1 is halogen or lower alkyl; R2 is hydrogen, lower alkyl, cycloalkyl, -(CH2)m- phenyl, wherein the phenyl ring may be substituted by lower alkoxy, or is (CH2)m-indolyl; R3 is C(O)O-lower alkyl, -C(O)OH, or a five membered heteroaromatic group, which rings may be substituted by lower alkyl or cycloalkyl; n is 0, 1 or 2 ; m is 0, 1 or 2 ; and their pharmaceutically acceptable acid addition salts. It has been found that this class of compoun ds show high affinity and selectivity for GABA A .alpha.5 receptor binding site s and might be useful for the treatment of cognitive enhancer or of cognitive disorders like Alzheimer's disease.
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