The invention relates to compounds which are represented by the formula 
wherein R1, R2, R3, R4, X and Y are as defined in the specification, as well as pharmaceutically acceptable salts thereof. The invention further relates to pharmaceutical compositions containing these compounds and to a process for their preparation. The compounds possess affinity towards metabotropic glutamate receptors and are therefore useful in the treatment or prevention of acute and/or chronic neurological disorders.
                            本发明涉及由下式所表示的化合物,其中R1、R2、R3、R4、X和Y在规范中定义,并且其药学上可接受的盐。本发明还涉及含有这些化合物的制药组合物以及其制备方法。这些化合物具有亲和力,可用于治疗或预防急性和/或慢性神经系统疾病,因为它们与代谢型谷
氨酸受体有关。