| abstract |
The invention relates to an ethynyl derivative of the formula I; where R is phenyl, 3-fluorophenyl, 4-fluorophenyl, or 2,5-difluorophenyl; or a pharmaceutically acceptable acid addition salt, in an enantiomerically pure form with absolute configuration, as shown in formula I. Compounds of general formula I are allosteric modulators of metabotropic glutamate receptors of subtype 5 (mGluR5), which exhibit improved biochemical, physico-chemical and pharmacodynamic properties compared to compounds known in the art. |