Novel aryl ether rearrangement catalyzed by lignin peroxidase of Phanerochaete chrysosporium

Abstract
Lignin peroxidase catalyzed the rearrangement of 2‐(2́‐methoxy‐4́‐propylphenoxy)‐1,3‐dihydroxypropane I to 3‐(2́‐methoxy‐4́‐propylphenoxy)‐1,2‐dihydroxypropane VI with a maximum product yield of 64%. The reaction was strongly inhibited by oxygen. The enzyme also catalyzed the rearrangement of 2‐(2́‐methoxy‐4́‐propylphenoxy) ‐1‐hydroxypropane IV to form 1‐(2́‐methoxy‐4́‐propylphenoxy)‐2‐hydroxypropane VIII. When IV was labeled with 18O in the 1‐hydroxyl group, all of the 18O was retained in the ether oxygen of the product VIII. A mechanism explaining these results involves: (i) one electron oxidation of the substrate to form an aryl cation radical; (ii) nucleophilic attack by the hydroxyl oxygen on the cation radical with release of a proton, resulting in a dioxolane radical intermediate; (iii) cleavage of the latter and subsequent hydrogen abstraction to form the rearranged product.