Mechanism of the Fe(III)-Catalyzed Peracetic Acid Oxidation of Catechol. A Biomimetic Reaction for Pyrocatechase

Article abstract of DOI:10.1021/jo00170a007

The Fe(III)-catalyzed peracetic acid (HOOAc) oxidation of catechol to cis,cis-muconic acid (MA) is proposed as a model for the action of the Fe(III)-containing dioxygenase pyrocatechase (catechol 1,2-dioxygenase).The yield of MA is a function of the reaching a maximum of 75 percent when the ratio / is 1000.No appreciable quantity of MA is formed in the absence of Fe(III).Evidence is presented that implicates peracetic acid and hydrogen peroxide as the active oxidants and o-benzoquinone as an intermediate in the reaction.Substrate binding to Fe(III) represents an important part of the reaction.The proposed mechanism for the model involves formation of an Fe(III)-catechol complex which is oxidized to an Fe(III)-o-benzoquinone species.The Fe(III)-quinone complex then undergoes nucleophilic attack at carbonyl by H2O2 to give a peroxide addition product which undergoes intramolecular nucleophilic addition at the adjacent carbonyl to give a dioxetane intermediate.Spontaneous opening of the dioxetane gives MA.