| abstract |
The present invention relates to an ethynyl derivative of formula (I), or a pharmaceutically acceptable salt or acid addition salt thereof, racemic mixtures, corresponding enantiomers and / or optical isomers and / or stereoisomers. Surprisingly, the compounds of formula (I) are positive allosteric modulators (PAMs) of the metabolic glutamate receptor subtype 5 (mGluR5) and thus have been found useful in the treatment of diseases associated with these receptors: Formula I In this formula, X is N or CR 1 ; Y is N or CR 2 ; Z is CH or N; R 4 is a 6-membered aromatic substituent, optionally substituted with one to three groups selected from halogen, lower alkyl, lower alkoxy and NRR ′ and containing 0, 1 or 2 nitrogen atoms; R 1 is hydrogen, lower alkyl, lower alkoxy, hydroxy, lower hydroxyalkyl, lower cycloalkyl, or heterocycloalkyl optionally substituted by hydroxy or alkoxy; R 2 is hydrogen, CN, lower alkyl or heterocycloalkyl; R and R 'are independently of each other hydrogen or lower alkyl. |