The present invention relates to a compound of general formula Iwherein R1, R2and R3are independently from each other hydrogen, lower alkyl, lower alkoxy, cycloalkyl, lower alkyl substituted by halogen or S-lower alkyl； or to a pharmaceutically acceptable acid addition salt, to a racemic mixture, or to its corresponding enantiomer and/or optical isomer thereof..It has been found that the compounds of general formula I are good inhibitors of the glycine transporter 1 (GlyT-1), and that they have a good selectivity to glycine transporter 2 (GlyT-2) inhibitors. The compounds may be used in the treatment of neurological and neuropsychiatric disorders.本發明係關於一種如通式I之化合物其中R1、R2及R3彼此獨立地係氫、低碳數烷基、低碳數烷氧基、環烷基、經鹵素原子取代之低碳數烷基或S-低碳數烷基；或係關於其醫藥可接受酸加成鹽、消旋混合物、或其相應對映異構體及/或光學異構體。已發現如通式I之化合物係甘胺酸轉運體1(GlyT-1)之良好抑制劑，及其等對甘胺酸轉運體2(GlyT-2)抑制劑具有良好選擇性。該等化合物可用於治療神經病症及神經精神病症。
