FIELD: medicine, pharmaceutics.SUBSTANCE: invention refers to a new ethinyl derivative of formula I in the form of a racemic mixture or respective enanthiomer and/or optic isomer and/or stereoisomer or to a pharmaceutically acceptable salt of the above compounds formed by acid addition. The compounds are allosteric modulators of metabotropic glutamate receptor subtype 5 (mGluR5) and can find application in treating diseases mediated by mGluR5 action, wherein a disease is schizophrenia, cognitive disorders, fragile X syndrome or autism. In formula I,U is N or C(R)； V is CH or N； W is CH or N； provided only one of the groups U, V or W is a nitrogen atom, Ris hydrogen, methyl or halogen； Y is -N(R)-, -O-, -C(R)(R)-, -CHO- or -CHS(O)-； Ris hydrogen or lower alkyl, whereas R/Rindependently represent hydrogen, hydroxy group, lower alkyl or lower alkoxy group； Ris phenyl or 5-6-merous heteroaryl containing 1-2 heteroatoms specified in nitrogen atoms, which can contain one or two substitutes specified in halogen or lower alkyl； R/Rindependently represent hydrogen, lower alkyl, hydroxy group, lower alkoxy group, C-C-cycloalkyl, CH-lower alkoxy group, or together with a carbon atom, to which they are attached, can form C-C-cycloalkyl, or a ring containing -CHOCH-； m is equal to 0, 1 or 2； if m is equal to 1, R/Rindependently represent hydrogen, lower alkyl, CH-lower alkoxy group, or together with a carbon atom, to which they are attached, can form C-C-cycloalkyl； or Rand Rtogether with a carbon atom, to which they are attached, can form C-cycloalkyl or a ring containing -(CH)OCH-； n is equal to 0 or 1； if n is equal to 1, R/Rindependently represent hydrogen, lower alkyl, CH-lower alkoxy group or together with a carbon atom, to which they are attached, can form C-C-cycloalkyl； Rand Rtogether with a carbon atom, to which they are attached, can form C-cycloalkyl； or if n is equal to 0, and Y is -N(R)-, then Rand Rtogether with a carbon atom and a nitrogen atom, to which they are
