The present invention relates to compounds of the general formula (IA) (IB)wherein R1, R2 independently from each other are lower alkyl or -(CH2)m-O-lower alkyl, or form together with the N atom to which they are attach aheterocyclic ring； R3 is hydrogen or lower alkyl； R4 is lower alkyl； hetarylis 3H-imidazole-2,4-diyl or 1H-pyrazole-1,4-diyl； n is 1 or 2 and m is 1 or 2；and to pharmaceutically acceptable acid addition salts thereof. Thesecompounds may be used for the treatment of Alzheimer's disease, Parkinson'sdisease, Huntington's disease, neuroprotection, schizophrenia, anxiety, pain,respiration deficits, depression, ADHD, drug addiction, such as amphetamine,cocaine, opioids, ethanol, nicotine, cannabinoids, or for the treatment ofasthma, allergic responses, hypoxia, ischaemia, seizure and substance abuse,or for use as sedatives, muscle relaxants, antipsychotics, antiepileptics,anticonvulsants and cardiaprotective agents for coronary artery disease andheart failure.
