An Example of the Oxidative De-esterification of an Isopropyl Ester. Its Role in the Metabolism of the Herbicide Flampropisopropyl

Abstract

1. Two mammalian metabolites of the herbicidal ester, flamprop-isopropyl (Barnon), have been characterized as products of ω-hydroxylation of the isopropoxycarbonyl grouping (-CO₂CHMe₂).

2. Hydroxylation at the methine group of this moiety, to afford an unstable lactol (-CO₂C(OH)Me₂) and thence the corresponding carboxylic acid also appears to occur. On the basis of experiments with rat liver microsomes, this pathway to the acid may be as important as the esterase-catalysed route.

3. Biomimetic oxidation studies with peroxytrifluoroacetic acid of a simple model of the herbicide (isopropyl acetate) have provided confirmation of the feasibility of the novel biotransformation.