The nucleophilic addition–elimination reaction of 2′, 3′, 5′-tri-O-acetyl-2-fluoro-O 6-[2-(4- nitrophenyl) ethyl] inosine (8) with [15N] benzylamine in the presence of triethylamine afforded the N 2-benzyl [2-15N] guanosine derivative (13) in a high yield, which was further converted into the N 2-benzoyl [2-15N] guanosine derivative by treatment with ruthenium trichloride and tetrabutyl-ammonium periodate. A similar sequence of reactions of 2′, 3′ ...