The invention relates to a compound of formula (I), its R,R- and S,S-enantiomeres and to their pharmaceutically acceptable acid addition salts. The compound of formula (I) and its R,R- and S,S-enantiomeres may be used as medicaments for the treatment of diseases, wherein the therapeutic indications include acute forms of neurodegeneration caused by stroke or brain trauma; chronic forms of neurodegeneration such as Alzheimer's disease, Parkinson's disease, Huntington's disease or ALS (amyotrophic lateral sclerosis); neurodegeneration associated with bacterial or viral infections, and diseases such as schizophrenia, anxiety, depression and chronic/acute pain.