The disclosure relates to compounds of formula IA, IB and ID, wherein the unspecified functional groups are disclosed in the specification. These compounds act as allosteric modulators of the metabotropic glutamate receptor subtype 5 (mGluR5) and may have utility in the treatment or prevention of schizophrenia, cognitive diseases, fragile X syndrome or autism. Example compounds include: 2-Methoxy-2-methyl-N-(5-phenylethynyl-pyridin-2-yI)-propionamide, N-[5-(3-Fluoro-phenylethynyI)-pyridin-2-yl]-2-methoxy-2-methyl-propionamide, 2,2-Dimethyl-N-(5-phenylethynyl-pyrimidin-2-yl)-propionamide, 2,2,N-Trimethyl-N-(5-phenylethynyl-pyrimidin-2-yl)-propionamide, 2,2-Dimethyl-N-(6-phenylethynyl-pyridazin-3-yl)-propionamide and N-[6-(3-Chloro-phenylethynyl)-pyridazin-3-yl]-2,2-dimethyl-propionamide.
Ethynyl derivatives as metabotropic glutamate receptor modulators