diseases related to a dysfunction of the GABAergic neurotransmission. A series of potent fluorinated analogues of the pyrazolopyrimidine Indiplon has been synthesized and evaluated in vitro as potential agents for imaging the GABA(A) receptor by means of positron emission tomography (PET). The most promising compound N-(3-fluoropropyl)-N-[3-[3-(thiophene-2-carbonyl)-pyrazolo[1,5-a]pyrimidin-7-yl]- phenyl]-acetamide