Aromatic ring cleavage in degradation of β‐O‐4 lignin substructure by Phanerochaete chrysosporium

The degradation of a β‐O‐4 lignin substructure model dimer, 4‐ethoxy‐3‐methoxyphenylglycerol‐β‐guaiacyl ether (I), by the white‐rot fungus Phanerochaete chrysosporium was investigated. The guaiacyl aromatic ring of the dimer (I) was first cleaved to give the cyclic carbonate of 4‐ethoxy‐3‐methoxyphenylglycerol (II) which was then converted to 4‐ethoxy‐3‐methoxyphenylglycerol (III). The carbonate carbon of (II) was found to be derived from the guaiacyl group of (I) based on tracer experiments with 13C.