FIELD : medicine; pharmaceuticals.SUBSTANCE : invention relates to ethynyl derivatives of formula I, where R1 is a hydrogen atom or F; n equals 1 or 2. Invention also relates to a pharmaceutical composition having negative allosteric modulator mGluR5 activity, based on said compounds. I.EFFECT : technical result is obtaining novel compounds and a pharmaceutical composition based thereon, which can be used in medicine for treating anxiety and pain, depression, Parkinson' s disease and gastroesophageal reflux disease (GERD).9 cl, 2 dwg, 4 ex