High turnover rates in pH-dependent alkene epoxidation using NaOCl and square-planar nickel(II) catalysts

Yoon, Hyun-Ki; Wagler, Thomas R.; O'Connor, Kenneth J.; Burrows, Cynthia J.

doi:10.1021/ja00167a078

Cited by 121 publications

(35 citation statements)

References 2 publications

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“…[17][18][19][20][21] Selected nickel complexes have been proven to be efficient catalysts in the challenging oxidation of alkanes and alkenes. For example [Ni II (OAc)(tpa)(H 2 O)] + (tpa = tris(pyridylmethyl)amine) and related systems [22][23][24] catalyze the oxidation of alkanes with mCPBA or H 2 O 2 as oxidant, while Ni-salen complexes 25,26 and Ni II salts 27 have been successfully applied as catalysts in alkene epoxidation in combination with NaOCl. For hypochlorite-based nickel-mediated oxidations, relatively little insight into the nature of the active species involved is available.…”

Section: Introductionmentioning

confidence: 99%

Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel–Oxygen Species

et al. 2016

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Abstract.Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed towards the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This is in part related to the "Oxo Wall" concept, which predicts that late transition elements cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO -at low temperature by UV/Vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a Ni III complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO -

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Section: Introductionmentioning

confidence: 99%

Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel–Oxygen Species

et al. 2016

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“…The addition of various concentrations of Fe2(HPTB)(OH)(NO3)4 and H202 in a 1:100 ratio to supercoiled pBR322 (0.015 mg/ml) resulted in an immediate reaction yielding nicked (single-stranded break) and linearized (double-stranded cut) plasmid. The amounts of supercoiled, nicked, and linear pBR322 obtained in each experiment were quantitated by densitometry and (5,34,35) were ineffective substitutes for H202 in affording double-stranded cleavage by Fe2(HPTB)(OH)(NO3)4 (Fig. 1).…”

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confidence: 99%

Double-stranded cleavage of pBR322 by a diiron complex via a "hydrolytic" mechanism.

Hanson

Que

1994

Proc. Natl. Acad. Sci. U.S.A.

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Treatment of plasmid pBR322 with Fe2-(HPTB)(OH)(NO3)4(HPTB =N,N,N',N '-tetrakis(2-benzimidazolylmethyl The complex Fe2(HPTB)(OH)(NO3)4 was synthesized according to published procedures (20). This complex has been shown to interact with H202 to form a 1:1 adduct (20).Plasmid pBR322 was purchased from Promega and transformed into Escherichia coli strains JM109 and HB101 by using CaCl2 (22). The cells were grown in Luria-Bertani broth containing tetracycline, amplified with chloramphenicol, and harvested; the plasmid was purified according to published procedures (23). Purity and quantity of DNA were determined by measuring the A26o/A280 ratio, using a Hoefer fluorometer and gel electrophoresis.Linearization of pBR322 with Fe2(HPTB)(OH)(NO34. The cleavage of pBR322 by Fe2(HPTB)(OH)(NO3)4/H202 was accomplished by mixing (in order) 1 ,ul of (0.15 mg/ml) pBR322, 1 ,ul of 0.1 M Tris HCl (pH 8.0) buffer, 1,ul (0.1 mM) of Fe2(HPTB)(OH)(NO3)4, 6 ,l of H20, and 1 ,ul of 9.0 mM H202 at 25°C. Immediately after mixing, the DNA solution was subjected to electrophoresis on a 1% agarose gel in TAE (40 mM Tris acetate/i mM EDTA) (24) and stained with ethidium bromide solution at 0.5 pg/ml to observe the cleaved DNA products. The amount of DNA was quantitated by photographing the fluorescence under UV light and analyzing the band intensities with a Pharmacia densitometer. The fluorescence intensities were corrected for the different binding affinities ofethidium bromide to form I vs. forms II and III (25). Lengthening the reaction time did not affect the amounts of nicked and linearized pBR322. The linearized pBR322 was recovered from the agarose gel by electroelution ofthe excised gel fragment, followed by phenol/chloroform extraction and precipitation with 3.0 M NaOAc and ethanol (24).Control experiments with Fe(EDTA)/H202 were done under conditions identical to those of Fe2(HPTB)(OH)(NO3)4/ Abbreviations:

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“…[223] The electrochemical Ni II -catalysed oxidation of olefins to epoxides has been reported with electrogenerated Ni III species derived from (salen)Ni II complexes. [18,224] The electrooxidation of alcohols to carboxylic acids has been described through electrogenerated nickel hydroperoxides. [17] …”

Section: ) Oxidative Coupling Reactionsmentioning

confidence: 99%

“…[16] Electrochemical reactions with oxidised nickel species have been reported for catalytic oxidation of various functional groups. [17,18] The use of these complexes, however, in catalytic CϪC bond-forming reactions has, to the best of our knowledge, not yet been reported.…”

Section: Introductionmentioning

confidence: 99%