SYNTHESIS OF [9-C-14]NONANOIC ACID VIA 2-THIENYL((CH3)-C-14)(CYANO)CUPRATE AND ITS OXIDATION BY NEWBORN PIGLET MUSCLE STRIPS

To determine if newborn piglet muscle could oxidize propionyl-CoA form ed by catabolism of odd chain fatty acids, an odd chain fatty acid lab eled in the terminal three carbons was needed. The synthetic scheme de scribed is based upon the displacement of a primary alkyl iodide, ethy l 8-iodooctanoate, by a [C-14]methyl group via an activated 2-thienyl( (CH3)-C-14) (cyano)cuprate intermediate, forming ethyl [9-C-14]nonanoa te. Ethyl [9-C-14]nonanoate was hydrolyzed in 6 N KOH and [9-C-14]nona noic acid recovered by ion-exchange chromatography. The yield of [9-C- 14]nonanoic acid was 40%, based on the initial amount of [C-14]methyl iodide. The cuprate and other precursors mere commercially available o r readily synthesized from available precursors. Mass spectroscopy of commercial and synthesized nonradioactive nonanoate determined an m/z of 159 for the product molecular ion, as expected. The C-14-labeled pr oduct phenacyl ester was found to cochromatograph in a C-18 reverse-ph ase HPLC system with similarly derivatized commercially obtained nonan oic acid. The synthesis should be generally applicable to labeling of compounds by displacement of primary alkyl iodides, where other reacti ve groups (e.g., carboxylic acid),if present, can be protected (e.g., converted to an ester). Muscle strips isolated from the triceps muscle of newborn piglets oxidized [9-C-14]nonanoic acid to (CO2)-C-14. Newb orn piglet muscle can oxidize propionyl-CoA produced during odd-chain fatty acid oxidation. (C) 1997 Academic Press.