The present invention relates to a compound of general formula I-A or I-Bwherein X is a bond or a -CH2- group； R1, R2 and R3 are independently from each other hydrogen, lower alkoxy, 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 formulas I-A and I-B are good inhibitors of the glycine transporter 1 (GlyT-1), and that they have a good selectivity to glycine transporter 2 (GlyT-2) inhibitors, suitable in the treatment of neurological and neuropsychiatric disorders.本發明係關於通式I-A或I-B之化合物，其中X為一鍵或-CH2-基團；R1、R2及R3彼此獨立地為氫、低碳烷氧基、經鹵素取代之低碳烷基或S-低碳烷基；或其醫藥學上可接受之酸加成鹽、外消旋混合物或其相應對映異構體及/或光學異構體。已發現通式I-A及I-B之化合物為甘胺酸轉運體1(GlyT-1)之良好抑制劑且其對甘胺酸轉運體2(GlyT-2)抑制劑具有良好選擇性，適於治療神經病症及神經精神病症。
