SYNTHESES OF 14C-LABELED PYRETHRIN I ALLETHRIN PHTHALTHRIN AND DIMETHRIN ON A SUBMILLIMOLE SCALE

Studies on the metabolic fate and degradation chemistry of pyrethroid insecticide chemicals are greatly facilitated by the use of compounds radiolabeled, in separate preparations, in the acid and alcohol moieties. Acid-labeled preparations were made by converting d-trans-chrysanthemic acid-1-14C (88 mg, 1.3 mCi/mm) into d-trans-d-pyrethrin-1-14C (68 mg, 1.3 mCi/mm), d-trans-d-allethrin-14C (43 mg, 1.3 mCi/mm), d-trans-dimethrin-14C (54 mg, 0.294 mCi/mm), and d-trans-phthalthrin-14C (47 mg, 0.294 mCi/mm), incorporating approximately 81% of the starting radiocarbon into the four pyrethroid preparations. Alcohol-labeled preparations were made by converting acetone-1,3-14C into d-trans-dl-ailethrin-14C (146 mg, 0.162 mCi/mm) and formaldehyde-14C into d-trans-phthalthrin-14C (299 mg, 0.276 mCi/mm). Each labeled compound had a high stereochemical purity and a radiochemical purity of greater than 99%. Detailed procedures were worked out for all conversions which took place in high yields except in one case: The synthesis of allethrin labeled in the alcohol moiety. © 1968 Taylor and Francis Group LLC.