Molecular oxygen monooxygenation with

Binding of 4-hydroxybenzoate (S) in the phenolate form facilitates flavin reduction by NADPH. After NADP+ release, the flavin hydroquinone reacts with molecular oxygen to yield the flavin C4a-hydroperoxide oxygenation species. Protonation of the distal oxygen of the peroxflavin facilitates the electrophilic attack on the nucleophilic carbon center of the substrate phenolate. After monooxygenation, the resulting hydroxyflavin is... 

Cytochromes P-450, the CO complexes of which have a characteristic absorption maximum at 450 nm, use molecular oxygen to catalyze monooxygenation of versatile organic compounds such as hydrocarbons, sulfides, and amines with reducing agents (Eq. 1) [27-33],... 

Cytochrome P450 enzymes use molecular oxygen to create ROS that monooxygenate many natural and xenobiotic species. With natural species and some foreign chemicals, the oxygenation is helpful, producing metabolites that are eliminated from the body. With others, however, such as aromatic hydrocarbons, the ROS metabolites are far more toxic than the parent compounds and create OS. Aerobic life is dependent upon the formation and deactivation of ROS. OS arises when ROS are formed at a rate that exceeds the rate of deactivation. 

After screening several reductants in the aerobic epoxidation of olefins catalyzed by nickel(II) complexes, it was found that an aldehyde acts as an excellent reductant when treated under an atmospheric pressure of molecular oxygen at room temperature (Scheme 6). Similar reactions have been reported in the patents. Propylene was monooxygenated into propylene oxide with molecular oxygen in the coexistence of metal complexes and aldehyde such as acetaldehyde " or crotonaldehyde, but the conversion of olefin and the selectivity of epoxide were never reached satisfactory levels. Recently, praseodymium(III) acetate was also shown to be an effective catalyst for the aerobic epoxidation of olefins in the presence of aldehyde. ... 

Monooxygenation of aromatics, alicyclic and linear alkanes with molecular oxygen is catalyzed by nonheme iron complexes in the anhydrous organic solvents in the presence of hydroquinones as electron and proton donors. Iron complexes are prepared in situ by stirring FeCla, pyrocatechol, and pyridine (mole ratio is 1 1 2) in acetonitrile or in pyridine. Isolated catecholatoiron complex is also used. Catalytic activity is greatly dependent on the kinds of hydroquinone and increases in the order of 2,5-di-t-butyl- t-butyl->methyl->H-hydroquinone. Non-substituted hydroquinone hardly exhibits activity, and the activity is controlled by the oxidation potential and steric effect of hydroquinones. 

Monooxygenation by Diiron Complexes with Molecular Oxygen... 

Most functional model monooxygenations by nonheme iron complexes are performed in the presence of electron and proton donors. Udenfriend used ascorbic acid for monooxygenation with ferrous salts and molecular oxygen in the... 

Recently, Egawa et al [68] demonstrated that an iron-oxo complex of P450cam was formed during the reaction with m-chloroperbenzoic acid. The absorption spectrum of the complex had two distinct absorption maxima at 367 and 694 nm (Fig. 3), which were almost indistinguishable from those of Compound I of chloroperoxidase, another type of thiolate-heme protein. As shown in the inset of Fig. 3, Compound I of the latter enzyme has the maxima at 368 and 689 nm. Unfortunately, however, this observation does not necessarily provide information whether the same species could be involved in the real monooxygenation reaction using molecular oxygen. 

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