Radiosynthesis of 6-[C-11]-d-glucose

Availability of 6-[C-11]-d-glucose will permit positron emission tomography (PET) investigations of glucose utilization derived from the pentose shunt which supports biosynthesis in tissues. The first radiosynthesis of 6-[C-11]-d-glucose is described. As much as 1 mCi of 6-[C-11]-d-glucose, sufficient for animal studies, is obtained from [C-11]CO₂ after 100 min with a 16% radiochemical yield (EOB). The radiosynthesis has many attractive features. The method uses [C-11]CH₃I and combines a Wittig reaction and a stereoselective OsO₄ catalyzed alkene hydroxylation. The OsO₄ hydroxylation of the [C-11]-labeled alkene (9) is accomplished in less than 10 min with high stereoselectivity (94:6) in favor of the 6-[C-11]-d-gluco-isomer. HPLC purification (C-18) of the protected labeled sugar removes the undesired 6-[C-11]-l-ido-sugar at an early stage and avoids the use of an expensive low-capacity ion-exchange HPLC column. OsO₄, a highly toxic reagent, is removed in the process by adsorption and inactivation on polymer-bound triphenylphosphine.