Dioxygenase-catalyzed oxidations

The dioxygenase-catalyzed oxidation of heterocyclic arenes occurs predominantly in a carbocycHc ring of the substrate [7], exemplified by the conversion by P. putida UV4 of quinoline, isoquinoline, quinoxaline, and quinazoline to the cw-diol products shown in Fig. 35 [57], but a recent report of the formation of cw-diol 46 (Fig. 36) by oxidation of 2-chloroquinoline by P putida [58] suggests the possibility that furtber products of this t) may become available as new chiral starting materials for synthetic applications. 

Figure 30 Dioxygenase-catalyzed oxidation of 2-naphthoic acid.

Kruger, H.-J. Iron-containing models of catechol dioxygenases, Biomimetic Oxidations Catalyzed by Transition Metal Complexes , Ed. Meunier, B. Imperial College Press London, 2000, pp. 363—413. 

Dioxygenases catalyze the incorporation of both atoms of molecular oxygen into the substrate. Microbial pyrocatechol dioxygenases contain non-heme iron as the sole cofactor and catalyze the oxidative cleavage of pyrocatechol to as,cis-muconic acid (intradiol equation 19) or to a-hydroxymuconic s-semialdehyde (extradiol equation 20).63"65 On... 

Tryptophan dioxygenase catalyzes the first step in the oxidative metabolism of L-tryptophan. L-Kynurenine is the product. 

Oxidation is an important catalytic phenomenon, and many industrially and scientifically interesting reactions can be characterized as oxidations. Section 5.5 focuses on chemically catalyzed oxidation reactions. The present section, however, focuses on elementary steps in biocatalytic oxidation reactions. Thus, special emphaisis is placed on elementary principles used by biocatalysts to generate powerful and reactive oxidizing species capable of performing oxidation reactions under mild reaction conditions. Biocatalytic oxidation reactions can vary from simple electron transfer redox reactions to peroxidase-, monooxygenase-, dioxygenase- and oxidase-type of reactions, the basic principles of which will be outlined in this section. 

Various systems oxidizing hydrocarbons and containing iron ions have been described which can be considered as models of non-heme mono- and dioxygenases [87] (see also Chapter X). Mononuclear iron derivatives have been used as catalysts in oxidations modeling the action of methane monooxygenase [88]. For example, a mononuclear iron carboxylate complex immobilized on a modified silica surface catalyzes oxidation of hexane in the presence of mercap-... 

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