Kinetics of iron(III) porphyrin catalyzed epoxidations

Traylor, Teddy G.; Marsters, James C.; Nakano, Taku; Dunlap, Beth E.

doi:10.1021/ja00305a042

Cited by 71 publications

(18 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, our kinetic study does not lead to an unambiguous assignment of the active intermediate in the catalytic reaction. It should be noted that the turnover frequency observed in the present catalytic study is in agreement with MnTDCPPCl cyclooctene HOCl r.t. olefin epoxidation 0.17 [7] FeTDCPPCl norbornene PhIO/MeOH r.t. catalyst oxidation 1.4 [12] FeTMpyP cyclooctene PhIO/MeOH r.t. olefin epoxidation 0.06 [13a] MnTPFPPCl cyclooctene 1 0 olefin epoxidation 0.25 [b] [a] Some values are calculated from the data reported in the references.…”

Section: Active Intermediatementioning

confidence: 99%

“…[11] There have been several kinetic studies of (porphyrin)iron-catalyzed olefin epoxidation with the soluble iodo-dimethoxybenzene as the terminal oxidant. [12][13][14] However, the kinetic and mechanistic details observed with iododimethoxybenzene are expected to be different from those with PhIO, given the structure and reactivity differences between the parent PhIO and dimethoxyiodobenzene. Because of the importance of iodosylbenzene as a terminal oxidant in metalloporphyrin-catalyzed olefin epoxidation, a detailed and clean kinetic study of iodosylbenzene or its derivative is needed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics of (Porphyrin)manganese(III)‐Catalyzed Olefin Epoxidation with a Soluble Iodosylbenzene Derivative

et al. 2006

View full text Add to dashboard Cite

We examined the kinetics of a well-behaved system for homogeneous porphyrin-catalyzed olefin epoxidation with a soluble iodosylbenzene derivative 1 as the terminal oxidant and Mn(TPFPP)Cl (2) as the catalyst. The epoxidation rates were measured by using the initial rate method, and the epoxidation products were determined by gas chromatography. The epoxidation rate was found to be first order with respect to the porphyrin catalyst and zero order on the terminal oxidant. In addition, we found the rate law to be sensitive to the nature and concentration of olefin substrates. Saturation kinetics were observed with all olefin substrates at high olefin concentrations, and the kinetic data are consistent with a Michaelis-Menten kinetic model. According to the observed saturation kinetic results, we propose that there is a complexation between the active oxidant and the substrate, and the rate-determining step is thought to be the breakdown of this putative substrate-oxidant complex that

show abstract

Section: Active Intermediatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetics of (Porphyrin)manganese(III)‐Catalyzed Olefin Epoxidation with a Soluble Iodosylbenzene Derivative

et al. 2006

View full text Add to dashboard Cite

show abstract

“…The iron-porphyrin, Fe(TDCPP) (CI) (Fig. 8), catalyzes alkene epoxidation by C6F510 with an initial rate as high as 300 turnovers/s [89], and more than 100000 mol epoxide are obtained/mol catalyst without appreciable destruction of this catalyst. More recently, the even more robust Fe [(tetrakis(2,6-dichlorophenyl)octabromoporphyrin] [Cl] complex was found to be able to hydroxylate norbornane with a 75% yield based on starting C6F510 and without loss of the catalyst [90] (Fig.…”

Section: -2 Model Systems Using Single Oxygen Atom Do-nors Like Imentioning

confidence: 99%

Chemical model systems for drug‐metabolizing cytochrome‐P‐450‐dependent monooxygenases

Mansuy

Battioni

1989

European Journal of Biochemistry

179

View full text Add to dashboard Cite

Monooxygenases are widely distributed enzymes which catalyze dioxygen activation using two electrons and two protons, with the insertion of one oxygen atom from O2 into a substrate and the formation of water (Eqn 1).A great number of these monooxygenases contain a heme protein called cytochrome P-450 which is the site of dioxygen activation. These cytochrome-P-450-dependent monooxygenases are involved in many steps of the biosynthesis and biodegradation of endogenous compounds such as steroids, fatty acids, prostaglandins and leukotrienes. They also play a key role in the oxidative metabolism of exogenous compounds such as drugs and other environmental products allowing their elimination from living organisms. Because of their wide distribution in living organisms and their very important role in biochemistry, pharmacology and toxicology, cytochromes P-450 have been the subject of many studies during the last 20 years. Thus, much is known about the structure and function of cytochromes P-450 (for recent reviews, see [l -41) and more than 60 cytochromes P-450 from various origins have been sequenced [5].However, because of the high molecular mass of cytochromes P-450 (about 50 kDa), it is still difficult to determine the detailed mechanism of substrate oxidations and the nature of the iron intermediates involved in these processes. In particular, it is difficult to determine the molecular structure of the iron-metabolite complexes formed from time to time during the metabolism of some classes of substrates. A possible way to solve these problems is to use biomimetic chemical systems involving iron-porphyrins.In fact, iron-porphyrin model systems for cytochromes P-450 may be used for three main purposes. The first is to determine the nature of the iron complexes involved as intermediates in the catalytic cycle of dioxygen activation and substrate hydroxylation by cytochrome P-450. Model ironporphyrin complexes for all these intermediates except one have been prepared and completely characterized by various spectroscopic techniques. Their structures have been established by X-ray analysis. The spectroscopic characteristics of these model complexes have been found to be very similar to Ahhreviutions. TMP, tetramesitylporphyrin; TPP, meso-tetraphenylporphyriu; TDCPP, tetra-2,6-dichlorophenylporphyrin.those of the corresponding enzymatic complexes and the use of these models has largely contributed to our present detailed knowledge of the catalytic cycle of cytochrome P-450. This first interest of the use of models has been described in previous reviews (see for instance [6 -91) and will not be treated in this article.A second objective of the use of chemical models for cytochromes P-450 is to understand as much as possible about the mechanisms of cytochrome P-450 during these reactions. In particular, the preparation and complete characterization of models for the cytochrome-P-450 -iron -metabolite complexes formed during the metabolism of some drugs or exogenous compounds should allow us to determine the chemical fu...

show abstract

“…Cytochrome P-450 catalyses many oxidation steps involved in biosynthesis, such as oxidation of steroid hormones, fatty acids and drug metabolism [1,2]. Intensive efforts have been made in the past to develop efficient homogeneous catalysts as models for cytochrome P-450 [3][4][5][6][7]. Although many properties of the enzymes have been mimicked [8,9], the challenge of finding better catalysts for hydroxylation of the inert C-H bond of alkanes and selective oxidation of alkenes and aromatic compounds as well as understanding the mechanism of catalytic oxidation of organic substrates remains an interesting task [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Cytochrome P‐450 model reaction: effects of substitution on the rate of aromatic hydroxylation

Safari¹,

Bahadoran²,

Hoseinzadeh³

et al. 2000

J. Porphyrins Phthalocyanines

View full text Add to dashboard Cite

Kinetics of iron(III) porphyrin catalyzed epoxidations

Cited by 71 publications

References 1 publication

Kinetics of (Porphyrin)manganese(III)‐Catalyzed Olefin Epoxidation with a Soluble Iodosylbenzene Derivative

Kinetics of (Porphyrin)manganese(III)‐Catalyzed Olefin Epoxidation with a Soluble Iodosylbenzene Derivative

Chemical model systems for drug‐metabolizing cytochrome‐P‐450‐dependent monooxygenases

Cytochrome P‐450 model reaction: effects of substitution on the rate of aromatic hydroxylation

Contact Info

Product

Resources

About