CHAPTER 6: Bio-catalyzed Aerobic Oxidation Reactions

Oxidoreductase enzymes enable a large variety of oxidation and oxyfunctionalization reactions at the expense of molecular oxygen, which is most commonly used in the form of air and at atmospheric pressure. Over the past decade, the number of available enzymes and methodologies enabling the performance of these types of reactions has increased significantly, thereby greatly complicating the navigation of the biochemical landscape of aerobic enzymatic reactions. This chapter provides an overview of bio-catalytic reactions that utilize dioxygen as a final electron acceptor or hydroxylating agent with a focus on more mature processes that allow at least gram-scale biotransformations with significant chemical turnovers, thus demonstrating practical applicability in organic synthesis. The described aerobic bio-catalytic reactions comprise: (a) carbon–hydrogen hydroxylation or halogenation; (b) mono- or di-hydroxylation as well as epoxidation or cleavage of alkenes; (c) Baeyer–Villiger oxidation; (d) oxidation of alcohols or aldehydes; oxidative decarboxylation; (e) oxidation of amines or imines; oxidation of organosulfur, organoboron or organoselenium compounds; and (f) oxidative carbon–carbon bond formation. Additionally, this chapter provides brief and selected mechanistic insights into the enzyme classes (i.e., oxygenases, oxidases, and dehydrogenases) that catalyze these biochemical transformations with often excellent chemo-, regio- and stereoselectivities.