Alkene epoxidations catalyzed by iron(III), manganese(III), and chromium(III) porphyrins. Effects of metal and porphyrin substituents on selectivity and regiochemistry of epoxidation

Traylor, Teddy G.; Miksztal, Andrew R.

doi:10.1021/ja00201a026

Cited by 143 publications

(46 citation statements)

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“…When reacted with (TPP) CrCl/-iodosylbenzene, styrene underwent cleavage to give benzaldehyde [13,14]. Using dodecylmethyl ammonium bromide (DDAB) as the phase transfer catalyst, styrene in 1,2-dichloroethane containing ruthenium chloride trihydrate was oxidized by hydrogen peroxide to give a good yield of benzaldehyde [15].…”

Section: Introductionmentioning

confidence: 99%

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Pal¹,

Gupta

Sen

2005

Transition Met Chem

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The kinetics of oxidation of a,b-unsaturated compounds by platinum(IV) in the presence of alkali {[OH ) ] ¼ (1-9) · 10 )3 mol dm )3 } have been investigated over the 303-318 K temperature range . The rate of the reaction is dependent on the first power of the concentrations of substrates, oxidant, and alkali. The rate constant increases with an increase in ionic strength and also with increasing dielectric constant of the medium. The oxidation rates follow the order: ACN > ACONH 2 > ACOO ) . The values of the third order rate constant (k 3 ) for the oxidation of acrylonitrile, acrylamide and acrylate are 1.24, 0.826 and 0.628 mol )2 dm 6 s )1 respectively, at 303 K. The oxidations of the substrates by PtCl 5 (OH) 2) take place by an inner-sphere mechanism. Platinum(IV) is reduced to platinum(II) by the substrates in a one-step two-electron transfer process to give reaction products. The major reaction product, HCHO, is identified from the reaction mixture using i.r. spectrometry, n.m.r. and C, H, N analysis. A tentative reaction mechanism, leading to the formation of products, has been suggested. The activation parameters of the reaction have been evaluated.

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Section: Introductionmentioning

confidence: 99%

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Pal¹,

Gupta

Sen

2005

Transition Met Chem

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“…In contrast, the choice of the transition metal has a substantial effect on the product selectivity of the oxidation (Table 1). This chemoselectivity may be understood in terms of the hydrogen-abstraction versus electron-transfer mechanisms proposed for the oxidation of cyclohexene by porphyrin complexes (Scheme 4), [14] since these also display a preference of chromium for allylic oxidations versus epoxidation by manganese. [14] For cyclohexenol, in the first step of Scheme 4, the direct hydrogen abstraction for the allylic oxidation (path 1) competes with the electron transfer for the epoxidation (path 2).…”

Section: Discussionmentioning

confidence: 99%

Allylic CH Oxidation versus Epoxidation of 2-Cyclohexenols, Catalyzed by Chromium- and Manganese-Substituted Polyoxometalates and Salen Complexes

et al. 2002

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2-Cyclohexenol (1) is oxidized chemoselectively to 2-cyclohexenone (2a) by the α-Keggin chromium-substituted polyoxometalate (POM) Ia as the catalyst and iodosobenzene as the oxygen source. For the chromium(salen) catalyst IIa the same chemoselectivity in favor of allylic CH oxidation is observed. The manganese-substituted POM Ib and the manganese(salen) complex IIb, however, afford appreciable amounts of the epoxy alcohol 2b. For the stereolabeled 5-tert-butyl-2-cyclohexenols 5, the diastereoselectivity of the epoxidation was appreciable (syn:anti 82:18) in the case of

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“…The cyclohexene oxidation led to both epoxidation and allylic oxidation whereas cyclooctene is clearly selective for epoxidation [13].…”

Section: Alkene Epoxidationmentioning

confidence: 96%

“…In this regard, an extensive amount of research has been focused on them, owing to the critical role they play in electron transfer [6] and photosynthesis [7] processes and also in catalytic oxygen atom transfer processes including hydroxylation [8][9][10][11] and epoxidation [12][13][14][15] of hydrocarbons. It is found that the reactivity of metalloporphyrin complexes depends on the central metal [13,16], the substituents on the porphyrin periphery [10,17,18], and the axially coordinated ligand [19][20][21]. Investigations in this area have been concentrated on the mechanism of the function of heme-containing enzymes such as cytochrome P-450 by designing metalloporphyrins as models [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen bond controlled formation of trans-dihydroxo porphyrinato platinum(IV) complexes: Synthesis, characterization and catalytic activity in olefin epoxidation

Alemohammad

Safari

Rayati

et al. 2015

Inorganica Chimica Acta

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Alkene epoxidations catalyzed by iron(III), manganese(III), and chromium(III) porphyrins. Effects of metal and porphyrin substituents on selectivity and regiochemistry of epoxidation

Cited by 143 publications

References 0 publications

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Allylic CH Oxidation versus Epoxidation of 2-Cyclohexenols, Catalyzed by Chromium- and Manganese-Substituted Polyoxometalates and Salen Complexes

Hydrogen bond controlled formation of trans-dihydroxo porphyrinato platinum(IV) complexes: Synthesis, characterization and catalytic activity in olefin epoxidation

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