This thesis presents a study of introduction of fluorine-18, a positron-emitting radioisotope to the designed position of molecules of adenosine type. This thesis also includes strategies of synthesising of precursors, into which the fluorine-18 isotope, either in fluoride ion form or as a suitable fluorine-containing small molecule, can be introduced. The synthesized labelled molecules make the investigation of adenosine-receptors by PET technique possible. Preliminary biological evaluation of one of these molecules, namely 5’-N-(2-[18F]fluoroethyl)-carboxamidoadenosine is also presented.

Two molecules were chosen to synthesise their fluorine-18 labelled forms: 5’-deoxy-5’-fluoro-adenosine and 5’-N-(2-fluoroethyl)-carboxamidoadenosine. Both compounds were labelled in two ways, each synthetic route includes nucleophilic fluorination with [18F]fluoride ion. 5’-Deoxy-5’-[18F]fluoro-adenosine would serve as a suitable model-compound for the synthesis of fluorine-18 labelled ligands; the appropriate modification of the adenine moiety leads to increased selectivity towards the chosen receptor subtype. As the radiochemical yields proved to be rather low, using either 5’-deoxy-5’-haloadenosines or N6-benzoyl 2’,3’-isopropylideneadenosine-5’-sulfonates as precursors, we had to resign to label adenosine at that (5’) position. Although N6-benzoyl 2’,3’-isopropylideneadenosine-5’-tosylate, one of these sulfonates was not proven to be a suitable precursor in the radiofluorination reactions, it served as an appropriate starting material in radioiodination reactions. 5’-N-(2-fluoroethyl)-carboxamidoadenosine ([18F]FNECA), as a fluorine-18 labelled analogue of NECA represents a PET isotope labelled agonist with given adenosine receptor specificity. It was synthesised in the following ways: in the reaction of [18F]fluoride with 5’-N,N-ethylene-2’,3’-O-isopropylidenecarboxamido-adenosine as well as by reacting 2-[18F]fluoroethylamine with 2’,3’-O-isopropylideneadenosine-5’-uronic acid. This latter route provides sufficient [18F]FNECA for the subsequent preliminary biological evaluation using PET-technique. According to the preliminary biological evaluation, agonist [18F]FNECA labelled with positron emitting isotope is capable of mapping the distribution for adenosine-receptors of P1 type, as well as investigating of receptor-regulation processes in vivo.