14 C labelled Metribuzine was synthetised in a five step synthesisfromsodium [1-14 C]pivalate (trimethyl acetic acid) via ω-bromo-[2- 14 C]pinacoline (1-bromo-3,3-dimethyl-butan-2-on) and trimethyl [2-14C]pyruvic acid. The total yield was 30% (calculated on sodium pivalate).