Metallo-porphyrin catalysed epoxidations with molecular oxygen

Baccouche, Mohamed; Ernst, Josef; Fuhrhop, Jürgen‐Hinrich; Schlözer, Rüdiger; Arzoumanian, Henri

doi:10.1039/c39770000821

Cited by 18 publications

(4 citation statements)

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“…However, the formation of hydro peroxides (ROOH) is remote as we have not used hydrogen peroxide or co-reductant like iso-butraldehyde. But, there are some reports [53][54][55] on the formation of hydroperoxide with auto air oxidation of alkenes. If that happens, epoxide formation through hydroperoxide route is possible.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Jinka

Sebastian

Jasra

2007

Journal of Molecular Catalysis A: Chemical

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Section: Reaction Mechanismmentioning

confidence: 99%

Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Jinka

Sebastian

Jasra

2007

Journal of Molecular Catalysis A: Chemical

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“…Alkene epoxidation has key importance in the chemical industry and often generates useful precursors for commodity used chemicals. , The industrially relevant Halcón process deals with the epoxidation of propylene and uses molybdenum complexes as a catalyst and tert -butylhydroperoxide ( t -BuOOH) as an oxidant. , While performing the molybdenum-catalyzed epoxidation of olefins using alkyl hydroperoxides, Sharpless et al have described the molybdenum-oxo core as an active catalytic moiety . Thus, the syntheses of molybdenum-oxo complexes having different coordination environments have gained valuable insight. − Due to their superior performance, various aspects of molybdenum porphyrin complexes are extensively studied, and their uses as epoxidation catalysts are also described in detail in the literature. − Corrole, a contracted porphyrin analogue, has gained a considerable research interest in recent times. − The discovery of facile and efficient synthetic protocols for corroles has fueled its rapid growth. , Because of the trianionic nature, small cavity size, and also electron-rich core structure, corrole tends to stabilize different metals in their possible higher oxidation states in comparison to their porphyrin counterparts. − Thus, it is logical to consider that oxo-molybdenum(V)-corrolato complexes will also act as potent epoxidation catalysts. However, similar literature studies using corrole as a metal chelator are very limited.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Application of Oxo-Molybdenum(V)-Corrolato Complexes in Epoxidation Reactions

Nayak

Sahu

et al. 2020

J. Org. Chem.

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Sharpless et al. have described, while performing the molybdenum-catalyzed epoxidation reaction of olefins using alkyl hydroperoxides, that the molybdenum-oxo moiety is an active catalytic species. Thus, continuous efforts have been made to synthesize molybdenum-oxo complexes of different ligand environments. While plenty of such works on molybdenum porphyrins are reported in the literature, related molybdenum corroles are very less reported. The synthesis and characterization of two new oxo-molybdenum(V)-corrolato complexes are described herein. Both the complexes have been fully characterized by several spectroscopic techniques in conjunction with single-crystal X-ray diffraction analysis. The efficacy of the oxo-molybdenum(V)-corrolato complexes for the catalytic epoxidation reaction of olefins with the help of hydroperoxides has also been explored. The catalytic application of oxo-molybdenum(V)-corrolato complexes in the epoxidation reaction has not been reported earlier. A mechanism has been proposed to explain the experimental findings.

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“…The propensity of t -BuOOH supported oxygenation systems to generate t -BuO • / t -BuOO • radicals even in cases in which high-valent iron-oxo units are otherwise regarded to play a prominent role (for instance, in shunt pathways of P-450), raises doubt whether these systems can be used as representative indicators of mechanism for other mainstream Gif reagents. Mechanistic insights regarding Gif systems employing H 2 O 2 or O 2 /Zn have been put forward by M. J. Perkins in a lucid reinterpretation (vide infra) of Barton's results, hinting toward an oxygen- and carbon-centered radical mechanism for the totality of Gif chemistry.…”

Section: Introductionmentioning

confidence: 99%

Functional Aspects of Gif-Type Oxidation of Hydrocarbons Mediated by Iron Picolinate H₂O₂-Dependent Systems: Evidence for the Generation of Carbon- and Oxygen-Centered Radicals

et al. 2000

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The present investigation explores the functional features of several novel and other previously ill-defined ferrous and ferric complexes of the picolinic acid anion (Pic), which are used to mediate Gif-type oxidation of hydrocarbons by H 2 O 2 . Complexes [Fe(Pic) 2 (py) 2 ], [Fe(Pic) 3 ]‚0.5py, [Fe 2 O(Pic) 4 (py) 2 ], [Fe 2 (µ-OH) 2 (Pic) 4 ], and FeCl 3 have been employed in oxygenations of adamantane by H 2 O 2 mostly in py/AcOH to reveal that tert-and sec-adamantyl radicals are generated in Gif solutions. The alleged absence of sec-adamantyl radicals from Gif product profiles has been previously interpreted as compelling evidence in support of a non-radical mechanism for the activation of secondary C-H sites in Gif chemistry. The product profile is entirely dictated by trapping of the diffusively free adamantyl radicals, since authentic tert-and sec-adamantyl radicals are shown to partition between dioxygen and protonated pyridine at 4% O 2 (in N 2 ), or between dioxygen and TEMPO at 100% O 2 , in a manner analogous to that observed in Gif oxygenations of adamantane. The low tert/sec selectivity (2.2-4.5) obtained, increasing with increasing dioxygen partial pressure, and the small intramolecular kinetic isotope effect values revealed by employing adamantane-1,3-d 2 (1.06(6) (Ar); 1.73(2) (4% O 2 in N 2 )), indicate the presence of an indiscriminate oxidant under inert atmosphere, coupled to a more selective oxidant at higher partial pressures of dioxygen. Gif oxygenation of DMSO by H 2 O 2 mediated by [Fe(Pic) 2 (py) 2 ] provides pyridine-trapped methyl radicals under argon, as expected for the addition reaction of hydroxyl radicals to DMSO. The reaction is progressively inhibited by increasing amounts of EtOH, generating pyridine-captured CH 3 • CHOH and • CH 2 CH 2 OH radicals. Quantification of the DMSO-versus EtOH-derived alkyl radicals affords an estimate of k EtOH /k DMSO equal to 0.34(3), in reasonable agreement with the kinetics of radiolytically produced hydroxyl radicals (k EtOH /k DMSO ) 0.29). The formation of methyl radicals in Gif oxygenation of DMSO is also supported by the quantitative generation of tert-adamantyl radicals in the presence of 1-iodoadamantane. These results are consistent with the action of hydroxyl radicals in Gif oxygenations by Fe II/III /H 2 O 2 (Ar), most likely coupled to substrate-centered alkoxyl radicals under O 2 . The oxygen-centered radicals perform H-atom abstractions from Gif substrates to generate diffusively free carbon-centered radicals, in accord with previously reported findings.

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Metallo-porphyrin catalysed epoxidations with molecular oxygen

Cited by 18 publications

References 0 publications

Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Synthesis, Characterization, and Application of Oxo-Molybdenum(V)-Corrolato Complexes in Epoxidation Reactions

Functional Aspects of Gif-Type Oxidation of Hydrocarbons Mediated by Iron Picolinate H₂O₂-Dependent Systems: Evidence for the Generation of Carbon- and Oxygen-Centered Radicals

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Metallo-porphyrin catalysed epoxidations with molecular oxygen

Cited by 18 publications

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Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Epoxidation of cycloalkenes with cobalt(II)-exchanged zeolite X catalysts using molecular oxygen

Synthesis, Characterization, and Application of Oxo-Molybdenum(V)-Corrolato Complexes in Epoxidation Reactions

Functional Aspects of Gif-Type Oxidation of Hydrocarbons Mediated by Iron Picolinate H2O2-Dependent Systems: Evidence for the Generation of Carbon- and Oxygen-Centered Radicals

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Functional Aspects of Gif-Type Oxidation of Hydrocarbons Mediated by Iron Picolinate H₂O₂-Dependent Systems: Evidence for the Generation of Carbon- and Oxygen-Centered Radicals