An efficient synthesis of racemic methylenecyclopropaneacetic acid has been developed. A mixture of the corresponding diastereomeric coenzyme A esters, one of which is the metabolite of the nonprotein amino acid hypoglycin from Blighia sapida directly responsible for its hypoglycemic potency, reacts stereospecifically with general acyl-CoA dehydrogenase from pig kidney to irreversibly inactivate the enzyme.