Stereochemical study of the reaction of molecular oxygen with alkylcobaloximes

Deniau, Jean; Gaudemer, A.

doi:10.1016/s0022-328x(00)81076-1

Cited by 17 publications

(3 citation statements)

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“…Gaudemer et al reported that photooxidation of optically active 1phenyl-2-hydroxyethyl(pyridine)cobaloxime, synthesized from (R)-2-phenyl-1,2-ethanediol 1-tosylate, proceeded in a stereospecific manner based on the measurement of optical rotation of the oxidation product1); however, others concluded that the oxidation proceeded with complete racemization.2),3) Jensen et al similarly oxidized optically active alkylcobaloxime such as 2-butyl(pyridine)cobaloxime, synthesized from (R)-2-butyl tosylate, followed it by reduction to give 2-butanol with no optical rotation.2) Recently, Gaudemer et al examined oxidation of 2-octyl(pyridine)cobaloxime, synthesized from (S)-2-octyl tosylate, but found the alcohol obtained optically inactive. 4) We observed that oxidation of optically active α-phenylethyl(pyridine)cobaloxime in dark and at low temperature proceeded partly stereospecifically, in contrast to the results of previous reports.2),3),4)…”

Section: Introductioncontrasting

confidence: 79%

Stereochemistry of oxidation of .ALPHA.-phenylethyl(pyridine)cobalt complexes.

1985

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Section: Introductioncontrasting

confidence: 79%

Stereochemistry of oxidation of .ALPHA.-phenylethyl(pyridine)cobalt complexes.

1985

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“…The exact mechanism of formation is still a matter of debate. It is however noteworthy that recemization of the α-carbon of the R group occurs during the Co−R → Co−O−OR transformation . When the R group is a primary or secondary alkyl, these reactions occur only upon irradiation of [(dmgH) 2 (py)Co III −R] species.…”

Section: Discussion: Partmentioning

confidence: 99%

Co(III)−Alkylperoxo Complexes: Syntheses, Structure−Reactivity Correlations, and Use in the Oxidation of Hydrocarbons

2000

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Crystalline [LCo(III)-OOR] complexes with strong-field ligands, L, afford ROO(*) and RO(*) radicals upon mild heating in solution. This fact allows oxidation of hydrocarbons by these complexes under mild conditions. The extent of hydrocarbon oxidation by discrete [LCo(III)-OOR] complexes depends on the nature of L, the solvent, the temperature, and the presence of other M(II) ions. Such systems are catalytic in the presence of excess ROOH.

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“…Oxygen insertion reactions have been reported for a number of transition-metal alkyl or aryl complexes, in particular for first-row metals such as chromium, iron, , cobalt, − nickel, and zinc. , During the past decade, several oxygen insertions with palladium(II) and platinum(II) methyl complexes have been reported. In 2009, Goldberg reported the reaction of [(PN)PtMe 2 ] (PN = 2-(di- tert -butylphosphino)methylpyridine) with oxygen to give the platinum(II) methylperoxo complex [(PN)PtMe(OOMe)] and the formation of a palladium(II) methylperoxo complex [(bipy)PdMe(OOMe)] (bipy = 2,2′-bipyridine) via the reaction of [(bipy)PdMe 2 ] (bipy = 2,2′-bipyridine) with oxygen (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Photolytic Activation of Late-Transition-Metal–Carbon Bonds and Their Reactivity toward Oxygen

Lam

Aguirre

et al. 2021

Organometallics

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The photolytic activation of palladium(II) and platinum(II) complexes [M(BPI)(R)] (R = alkyl, aryl) featuring the 1,3-bis(2-pyridylimino)isoindole (BPI) ligand has been investigated in various solvents. In the absence of oxygen, the formation of chloro complexes [M(BPI)Cl] is observed in chlorinated solvents, most likely due to the photolytic degradation of the solvent and formation of HCl. The reactivity of the complexes toward oxygen has been studied both experimentally and computationally. Excitation by UV irradiation (365 nm) of the metal complexes [Pt(BPI)Me] and [Pd(BPI)Me] leads to distortion of the square-planar coordination geometry in the excited triplet state and a change in the electronic structure of the complexes that allows the interaction with oxygen. TD-DFT computational studies suggest that, in the case of palladium, the Pd(III) superoxide intermediate [Pd(BPI)(κ 1 -O 2 )Me] is formed and, in the case of platinum, the Pt(IV) peroxide intermediate [Pt(BPI)(κ 2 -O 2 )Me]. For alkyl complexes where metal−carbon bonds are sufficiently weak, the photoactivation leads to the insertion of oxygen into the metal−carbon bond to generate alkylperoxo complexes: for example [Pd(BPI)OOMe], which has been isolated and structurally characterized. For stronger M−C(aryl) bonds, the reaction of [Pt(BPI)Ph] with O 2 and light results in a Pt(IV) complex, tentatively assigned as the peroxo complex [Pt(BPI)(κ 2 -O 2 )Ph], which in chlorinated solvents reacts further to give [Pt(BPI)Cl 2 Ph], which has been isolated and characterized by scXRD. In addition to the facilitation of oxygen insertion reactions, UV irradiation can also affect the reactivity of other components in the reaction mixture, such as the solvent or other reaction products, which can result in further reactions. Labeling studies using [Pt(BPI)(CD 3 )] in chloroform have shown that photolytic reactions with oxygen involve degradation of the solvent.

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Stereochemical study of the reaction of molecular oxygen with alkylcobaloximes

Cited by 17 publications

References 9 publications

Stereochemistry of oxidation of .ALPHA.-phenylethyl(pyridine)cobalt complexes.

Stereochemistry of oxidation of .ALPHA.-phenylethyl(pyridine)cobalt complexes.

Co(III)−Alkylperoxo Complexes: Syntheses, Structure−Reactivity Correlations, and Use in the Oxidation of Hydrocarbons

Photolytic Activation of Late-Transition-Metal–Carbon Bonds and Their Reactivity toward Oxygen

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