Solid-Phase Catalytic Hydrogenation of Uracil with Tritium: Synthesis of Tritium-Labeled β-Alanine

Abstract

Solid-phase catalytic hydrogenation of uracil with gaseous tritium was studied. Isotope exchange of protons at C5 and C6 is accompanied by hydrogenation of the 5,6-double bond in the pyrimidine core; as a result, a mixture of tritium-labeled uracil and 5,6-dihydrouracil is formed. The influence of the reaction temperature and time on the yield and molar radioactivity of these compounds was examined. The best conditions for cleavage of 5,6-dihydrouracil into β-alanine were found. [5,6-3H2]Uracil (49 Ci mmol-1), [5,5,6,6-3H4]5,6-dihydrouracil (100 Ci mmol-1), and [2,2,3,3-3H4]β-alanine (100 Ci mmol-1) were prepared.