SYNTHESIS OF THE TRITIUM-LABELED SCH-58261, A NEW NONXANTHINE A(2A)-ADENOSINE RECEPTOR ANTAGONIST

The tritium labeled form of mino-7-(2-phenylethyl)-2-(2-furyl)-pyrazol o[4,3-e] 1,2,4-triazolo[1,5-c]pyrimidine (H-3-SCH 58261) was obtained by reduction of yl)-pyrazolo[4,3-e]1,2,4-triazolo[1,5-c]pyrimidine wit h tritium gas in the presence of 10% Pd-C. Final product was purified by HPLC to give the title H-3-SCH 58261 with radiochemical purity of 9 9% and specific activity of 68.6 Ci/mmol. H-3-SCH 58261 bound A(2A) re ceptors in rat striatal membranes (specific binding > 90%) with K-d ac id B-max value of 0.70 nM and 971 fmol/mg of protein, respectively. H- 3-SCH 58261 represents a useful tool for a further characterization of A(2A) adenosine receptor subtype.