Enzymatic Oxidation of Methyl Groups on Aromatic Heterocycles: A Versatile Method for the Preparation of Heteroaromatic Carboxylic Acids

Heteroarenes such as pyrrole, pyrazole, furan, thiophene, pyridine, and pyrazine substituted by one or more methyl groups can be oxidized to the corresponding monocarboxylic acids by the bacterial strain Pseudomonas putida ATCC 33015 grown on para-xylene. Within 50 h on a 20 L scale, 20 gL−1 of 2,5-dimethyl-pyrazine (1 ) could be converted in quantitative yield to 5-methylpyrazine-2-carboxylic acid (as the sodium salt 2).