Synthesis of 14C‐labelled 5‐hydroxy‐4‐keto‐valeric acid and 4, 5‐dioxo‐valeric acid

Abstract
5‐Hydroxy‐4‐keto [4‐14C]valeric acid was prepared from 5‐amino [4‐14C]levulinic acid. The synthesis of 5‐hydroxy‐4‐keto [1‐14C]valeric acid (4) was achieved by Grignard reaction of 1‐benzyloxy‐4‐bromo‐2‐butanone ethylene acetal (1) with 14CO2 and subsequent removal of the protecting groups.4,5‐Dioxo [1‐ or 4‐14C]valeric acid was made by oxidation of the α‐ketol group with cupric acetate.