The present invention relates to ethynyl derivatives of formula I wherein X is N or C-R, wherein R is hydrogen or halogen； G is N or CH； with the proviso that maximum one of G or X can be nitrogen； R1 is phenyl or pyridinyl, which are optionally substituted by halogen； R2 is hydrogen, lower alkyl, hydroxy, lower alkoxy or C(O)O-benzyl； R3, R3’, R4, R4’, R6, R6’ are independently from each other hydrogen or lower alkyl； or R6 and R4 may form together with the carbon atom to which they are attached a C4-6-cycloalkyl ring, if m is 0 and n is 1 or 2； R5 is hydrogen or lower alkyl； n is 0, 1 or 2； m is 0 or 1； with the proviso that n and m are not simultaneously 0； or to a pharmaceutically acceptable acid addition salt, to a racemic mixture, or to its corresponding enantiomer and/or optical isomer and/or stereoisomer thereof. It has now surprisingly been found that the compounds of general formula I are positive allosteric modulators (PAM) of the metabotropic glutamate receptor subtype 5 (mGluR5). They may be used for the treatment of schizophrenia or cognitive disorders.本發明係關於式I之乙炔基衍生物：其中X 係N或C-R，其中R係氫或鹵素；G 係N或CH；限制條件為G或X中至多一個可為氮；R1 係苯基或吡啶基，其視需要經鹵素取代；R2 係氫、低碳數烷基、羥基、低碳數烷氧基或C(O)O-苄基；R3、R3'、R4、R4'、R6、R6' 相互獨立地為氫或低碳數烷基；或若m係0且n係1或2，則R6及R4可與其等所連接之碳原子一起形成C4-6-環烷基環；R5 係氫或低碳數烷基；n 係0、1或2；m 係0或1；限制條件為n及m不同時為0；或其醫藥上可接受的酸加成鹽、外消旋混合物、或其相應的對映異構體及/或光學異構體及/或立體異構體。現已驚訝地發現該等通式I化合物係代謝型麩胺酸受體亞型5(mGluR5)之正向異位調節劑(PAM)。其可用於治療精神分裂症或認知障礙。
