THE SYNTHESIS OF NO-CARRIER-ADDED [C-11] UREA FROM [C-11] CARBON-DIOXIDE AND APPLICATION TO [C-11] URACIL SYNTHESIS

No-carrier-added [C-11]urea has been synthesized by bubbling cyclotron -produced [C-11]carbon dioxide directly into a tetrahydrofuran solutio n of lithium bis(trimethylsilyl)amide, followed by hydrolysis of the C -11 labeled adduct with aqueous ammonium chloride. Using this simple, one-pot method, [C-11]urea was produced in 55-70% radiochemical yield (decay-corrected) in 16 min following end-of-bombardment (or in 10 min following the introduction of the [C-11]carbon dioxide). The [C-11]ur ea thus produced was converted to [C-11]uracil (carrier-added) in 40-7 5% decay-corrected radiochemical yield by condensation with diethyl ma late in presence of fuming sulfuric acid. (C) 1997 Elsevier Science Lt d.