The present invention relates to compounds of general formula (I) wherein R1 is aryl or heteroaryl, which are optionally substituted by one, two or three substituents, selected from lower alkyl, halogen, lower alkyl substituted by halogen, hydroxy, lower alkyl substituted by hydroxy, lower alkoxy, lower alkoxy substituted by halogen, cyano or nitro R 2 is halogen, lower alkyl or cyano R 3 is hydrogen, lower alkyl or lower alkyl substituted by halogen R 4 is hydrogen or lower alkyl R5, R 6 are hydrogen, lower alkyl, or may form together with the N-atom to which they are attached a heterocycloalkyl ring or a pharmaceutically acceptable acid addition salt, a racemic mixture or its corresponding enantiomer and/or optical isomers thereof. The compounds may be used for the treatment of schizophrenia, obsessive-compulsive personality disorder, major depression, bipolar disorders, anxiety disorders, normal aging, epilepsy, retinal degeneration, traumatic brain injury, spinal cord injury, post-traumatic stress disorder, panic disorder, Parkinsons disease, dementia, Alzheimers disease, cognitive impairment, chemotherapy-induced cognitive dysfunction ("chemobrain"), Down syndrome, autism spectrum disorders, hearing loss, tinnitus, spinocerebellar ataxia, amyotrophic lateral sclerosis, multiple sclerosis, Huntingtons disease, stroke, and disturbances due to radiation therapy, chronic stress, or abuse of neuro-active drugs, selected from alcohol, opiates, methamphetamine, phencyclidine and cocaine.La presente invención se refiere a compuestos de la fórmula general (ver Fórmula) en donde R1 es arilo o heteroarilo, los cuales son opcionalmente sustituidos por uno, dos o tres sustituyentes, seleccionados a partir de alquilo inferior, halógeno, alquilo inferior sustituido por halógeno, hidroxi, alquilo inferior sustituido por hidroxi, alcoxi inferior, alcoxi inferior sustituido por halógeno, ciano o nitro R2 es halógeno, alquilo inferior o ciano R3 es hidrógeno, alquilo inferior o a
