SYNTHESIS OF 8-[O-18]HYDROXY-2'-DEOXYGUANOSINE

8-[O-18]Hydroxy-2'-deoxyguanosine was synthesized starting from 8-brom o-2'-deoxyguanosine and the sodium salt of [O-18]benzyl alcohol, resul ting in the intermediate 8-[O-18]benzyloxy-2'-deoxyguanosine. Subseque nt reduction by catalytic transfer hydrogenation, yielded the desired product 8-[O-18]hydroxy-2'-deoxyguanosine. 8-Bromo-2'-deoxyguanosine w as synthesized from 2'-deoxyguanosine by treatment with Br-2. The sodi um salt of [O-18]benzyl alcohol was prepared by treatment of ethyl ben zimidate hydrochloride with (H2O)-O-18 (95%), LiAlH4 and sodium hydrid e. Starting from (H2O)-O-18 the overall yield of 8-[O-18]hydroxy-2'-de oxyguanosine was approximately 4%. The isotopic purity was calculated to be 93.4 atom% based on CC-MS measurements. The chemical purity and the isotopic purity comply with the planned application, namely as int ernal standard for the determination of 8-hydroxy-2'-deoxyguanosine by CC-MS,