Chloroperoxidase‐Catalyzed Achmatowicz Rearrangements

Chloroperoxidase from Caldariomyces fumago catalyzes the selective oxidation of furfuryl alcohols in an Achmatowicz‐type ring expansion. In combination with glucose oxidase as oxygen‐activating biocatalyst, a purely enzymatic, aerobic protocol for the synthesis of 6‐hydroxypyranone building blocks is obtained. Thanks to an only modest stereochemical bias of the oxygenating heme protein, optically active alcohols of either configuration are converted without a significant mismatch opening up opportunities for enantioselective multienzymatic cascades. Balancing the oxidase‐driven aerobic activation, extended enzyme half‐lives and productive conversion of poorly soluble and slowly reacting substrates can be achieved with high yields of the six‐membered O‐heterocycles.