- Formation of a Ruthenium(V) - Imido complex and the reactivity in substrate oxidation in water through the nitrogen non-rebound mechanism
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A RuII - NH3 complex, 2, was oxidized through a proton-coupled electron transfer (PCET) mechanism with a CeIV complex in water at pH 2.5 to generate a RuV═NH complex, 5. Complex 5 was characterized with various spectroscopies, and the spin state was determined by the Evans method to be S = 1/2. The reactivity of 5 in substrate C-H oxidation was scrutinized in acidic water, using water-soluble organic substrates such as sodium ethylbenzene-sulfonate (EBS), which gave the corresponding 1-phenylethanol derivative as the product. In the substrate oxidation, complex 5 was converted to the corresponding RuIII - NH3 complex, 3. The formation of 1-phenylethanol derivative from EBS and that of 3 indicate that complex 5 as the oxidant does not perform nitrogen-atom transfer, in sharp contrast to other high-valent metal-imido complexes reported so far. Oxidation of cyclobutanol by 5 afforded only cyclobutanone as the product, indicating that the substrate oxidation by 5 proceeds through a hydride-transfer mechanism. In the kinetic analysis on the C-H oxidation, we observed kinetic isotope effects (KIEs) on the C-H oxidation with use of deuterated substrates and remarkably large solvent KIE (sKIE) in D2O. These positive KIEs indicate that the rate-determining step involves not only cleavage of the C-H bond of the substrate but also proton transfer from water molecules to 5. The unique hydride-transfer mechanism in the substrate oxidation by 5 is probably derived from the fact that the RuIV - NH2 complex (4) formed from 5 by 1e-/1H+ reduction is unstable and quickly disproportionates into 3 and 5.
- Ishizuka, Tomoya,Kogawa, Taichi,Makino, Misaki,Shiota, Yoshihito,Ohara, Kazuaki,Kotani, Hiroaki,Nozawa, Shunsuke,Adachi, Shin-Ichi,Yamaguchi, Kentaro,Yoshizawa, Kazunari,Kojima, Takahiko
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- Mechanism of alcohol oxidation mediated by copper(II) and nitroxyl radicals
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2,2′-Bipyridine-ligated copper complexes, in combination with TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), are highly effective catalysts for aerobic alcohol oxidation. Considerable uncertainty and debate exist over the mechanism of alcohol oxidation mediated by CuII and TEMPO. Here, we report experimental and density functional theory (DFT) computational studies that distinguish among numerous previously proposed mechanistic pathways. Oxidation of various classes of radical-probe substrates shows that long-lived radicals are not formed in the reaction. DFT computational studies support this conclusion. A bimolecular pathway involving hydrogen-atom-transfer from a CuII-alkoxide to a nitroxyl radical is higher in energy than hydrogen transfer from a CuII-alkoxide to a coordinated nitroxyl species. The data presented here reconcile a collection of diverse and seemingly contradictory experimental and computational data reported previously in the literature. The resulting Oppenauer-like reaction pathway further explains experimental trends in the relative reactivity of different classes of alcohols (benzylic versus aliphatic and primary versus secondary), as well as the different reactivity observed between TEMPO and bicyclic nitroxyls, such as ABNO (ABNO = 9-azabicyclo[3.3.1]nonane N-oxyl).
- Ryland, Bradford L.,McCann, Scott D.,Brunold, Thomas C.,Stahl, Shannon S.
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- Controlled synthesis of hydroxyapatite-supported palladium complexes as highly efficient heterogeneous catalysts
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Achieving precise control of active species on solid surfaces is one of the most important goals in the development of highly functionalized heterogeneous catalysts. The treatment of hydroxyapatites with PdCl2(PhCN)2 gives two new types of hydroxyapatite-bound Pd complexes. Using the stoichiometric hydroxyapatite, Ca10(PO4)6(OH)2, we found that monomeric PdCl2 species can be grafted on its surface, which are easily transformed into Pd0 particles with narrow size distribution in the presence of alcohols. Such metallic Pd species can effectively promote alcohol oxidation using molecular oxygen and are shown to give a remarkably high TON of up to 236000. Another monomeric PdII phosphate complex can be generated at a Ca-deficient site of the nonstoichiometric hydroxyapatite, Ca9(HPO4)(PO4)5(OH), affording a catalyst with PdII structure and high activity for the Heck and Suzuki reactions. To the best of our knowledge, the PdHAP are one of the most active heterogeneous catalysts for both alcohol oxidation under an atmospheric O2 pressure and the Heck reaction reported to date. These Pd catalysts are recyclable in the above organic reactions. Our approach to catalyst preparation based on the control of Ca/P ratios of hydroxyapatites represents a particularly attractive method for the nanoscale design of catalysts. Copyright
- Mori, Kohsuke,Yamaguchi, Kazuya,Hara, Takayoshi,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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- Catalytic reactions of chlorite with a polypyridylruthenium(ii) complex: Disproportionation, chlorine dioxide formation and alcohol oxidation
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cis-[Ru(2,9-Me2phen)2(OH2) 2]2+ reacts readily with chlorite at room temperature at pH 4.9 and 6.8. The ruthenium(ii) complex can catalyze the disproportionation of chlorite to chlorate and chloride, the oxidation of chlorite to chlorine dioxide, as well as the oxidation of alcohols by chlorite. The Royal Society of Chemistry 2012.
- Hu, Zongmin,Du, Hongxia,Man, Wai-Lun,Leung, Chi-Fai,Liang, Haojun,Lau, Tai-Chu
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- Kinetic study of ruthenium (VI)-catalyzed oxidation of 2-propanol by alkaline hexacyanoferrate (III)
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The kinetics of Ru(VI)-catalyzed oxidation of 2-propanol by hexacyanoferraie(III) was investigated in alkaline media using a spectrophotometric technique. The reaction shows first order in [Ru(VI)], a Michaelis-Menten-type dependence on [2-propanol], a fractional order in [Fe(CN)63-] and a complicated variation on [OH-]. A reaction mechanism which involves two active catalytic species is proposed. Each of these species forms an intermediate complex with the substrate. These complexes decompose slowly, producing ruthenium(IV) complexes, which are reoxidized by hexacyanoferrate(III) in subsequent steps. The theoretical rate law obtained is in complete agreement with all the experimental observations. Copyright
- Mucientes,Poblete,Rodriguez,Santiago
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- Transition-Metal-Free Ring-Opening Reaction of 2-Halocyclobutanols through Ring Contraction
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The present work describes the preparation of halohydrins from 2-halocyclobutanones by means of reactions with Grignard reagents at ?78 °C. We discovered that the prepared cyclobutanols underwent a thermal ring-opening reaction. Depending on the structure of the starting cyclobutanol, different products were formed. More specifically, 1-substituted 2-bromocyclobutan-1-ol was found to open to γ-substituted butyrophenones. A novel 1,3-dihydro-2H-inden-2-ylidene derivative was obtained for indene-derived cyclobutanols. Based on the outcomes of the performed experiments, a mechanism for the ring-opening of cyclobutanols can be proposed.
- ?ubiňák, Marek,Edlová, Tereza,Oeser, Petr,Tobrman, Tomá?
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- Mechanistic insight into alcohol oxidation by high-valent iron-oxo complexes of heme and nonheme ligands
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(Chemical Equation Presented) Iron-mediated oxidation: High-valent iron(IV)-oxo complexes of heme and nonheme ligands are generated in situ and are used in mechanistic studies of alcohol oxidation (see scheme). It is proposed that the oxidation of alcohols occurs by an α-CH hydrogen atom abstraction followed by electron transfer. Porp = porphyrin.
- Na, Young Oh,Suh, Yumi,Mi, Joo Park,Mi, Sook Seo,Kim, Jinheung,Nam, Wonwoo
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- Hydroxyapatite-supported palladium nanoclusters: A highly active heterogeneous catalyst for selective oxidation of alcohols by use of molecular oxygen
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Treatment of a stoichiometric hydroxyapatite (HAP), Ca10(PO 4)6(OH)2, with PdCl2(PhCN) 2 gives a new type of palladium-grafted hydroxyapatite. Analysis by means of powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX), IR, and Pd K-edge X-ray absorption fine structure (XAFS) proves that a monomeric PdCl2 species is chemisorbed on the HAP surface, which is readily transformed into Pd nanoclusters with a narrow size distribution in the presence of alcohol. Nanoclustered Pd 0 species can effectively promote the alcohol oxidation under an atmospheric O2 pressure, giving a remarkably high turnover number (TON) of up to 236 000 with an excellent turnover frequency (TOF) of approximately 9800 h-1 for a 250-mmol-scale oxidation of 1-phenylethanol under solvent-free conditions. In addition to advantages such as a simple workup procedure and the ability to recycle the catalyst, the present Pd catalyst does not require additives to complete the catalytic cycle. The diameters of the generated Pd nanoclusters can be controlled upon acting on the alcohol substrates used. Oxidation of alcohols is proposed to occur primarily on low-coordination sites within a regular arrangement of the Pd nanocluster by performing calculations on the palladium crystallites.
- Mori, Kohsuke,Hara, Takayoshi,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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- Generation and Rearrangement of (1-Hydroxycyclopropyl)- A nd (1-Hydroxycyclobutyl)carbene
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Photolysis of exo-1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclopropan-1-ol and exo-1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclobutan-1-ol in benzene-d6 produces (1-hydroxycyclopropyl)- A nd (1-hydroxycyclobutyl)carbene respectively. It was observed that (1-hydroxycyclopropyl)carbene rearranges to cyclobutanone whereas (1-hydroxycyclobutyl)carbene forms cyclopentanone. Formation of both ketones is attributed to tautomerization of the corresponding enols that arise from ring expansion of the carbenes. Products assignable to intramolecular C-H insertions were not detected in the photolysates.
- Deangelo, Joseph D.,Hatano, Sayaka,Thamattoor, Dasan M.
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- Reactivity of aqueous Fe(IV) in hydride and hydrogen atom transfer reactions
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Oxidation of cyclobutanol by aqueous Fe(IV) generates cyclobutanone in ~70% yield. In addition to this two-electron process, a smaller fraction of the reaction takes place by a one-electron process, believed to yield ring-opened products. A series of aliphatic alcohols, aldehydes, and ethers also react in parallel hydrogen atom and hydride transfer reactions, but acetone and acetonitrile react by hydrogen atom transfer only. Precise rate constants for each pathway for a number of substrates were obtained from a combination of detailed kinetics and product studies and kinetic simulations. Solvent kinetic isotope effect for the self-decay of Fe(IV), kH2O/kD2O, = 2.8, is consistent with hydrogen atom abstraction from water.
- Pestovsky, Oleg,Bakac, Andreja
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- Effects of substrate structure and temperature on the stereospecificity of secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus
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Enzymes from thermophilic microorganisms are of considerable interest in biotechnological applications. The temperature dependence of the rates of reaction of the enantiomers of secondary alcohols with a secondary alcohol dehydrogenase (SADH) from a thermophilic bacterium, Thermoanaerobacter ethanolicus, has been determined. These results demonstrate a novel temperature-dependent reversal of stereospecificity. At temperatures below 26 °C, (S)-2-butanol is a better substrate than (R)-2-butanol on the basis of k(cat)/K(m) values; however, above 26 °C, (R)-2-butanol is a better substrate than (S)-2-butanol. (S)-2-Pentanol is the preferred substrate up to 60 °C; however, our data predict that (R)-2-pentanol would be preferred above 70 °C. (S)-2-Hexanol is predicted to be the preferred enantiomer up to 240 °C. At 50 °C, the k(cat)/K(m) values for oxidation of S alcohols obey a linear free energy relationship with respect to increasing chain length, indicating a constant mechanism. However, the R alcohols show a convex plot, suggesting that there is a chain-length-dependent change in the rate-determining step. 3-Pentanol, cyclobutanol, and cyclopentanol are also good substrates on the basis of comparison of their k(cat)/K(m) values with those of 2-propanol.
- Pham,Phillips
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- In search of α-eliminations of carbon induced by sixteen electron iron: photolysis and thermolysis of derivatives of phenyl substituted cyclobutanes and cyclopropanes
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Photolysis of dicarbonyl(ε5-cyclopentadienyl)(1-phenylcyclobutane-1-carbonyl)iron is proposed to give the hydride complex Ph(cyclobutenyl)Fe(Cp)(CO)H which dissociates to 1-phenylcyclobutene and FpH (Fp = ε5-cyclopentadienyldicarbonyliron).The FpH complex can oxidatively add to the sixteen electron acyl or ? complexes (Ph(cyclobutyl)-C(O)FeCp(CO) and Ph(cyclobutyl)FeCp(CO) respectively) to produce phenylcyclobutane and 1-phenylcyclobutane carboxaldehyde.Photolysis of dicarbonyl(ε5-cyclopentadienyl)(1-phenylcyclopropyl-1-carbonyl)iron gives a ? complex with no further reaction.Substitution of CO with PPh3 and thermolysis producrally substituted ?-allyl complex.In neither the cyclobutyl nor the cyclopropyl case did the reactions give isolable carbene complexes; apparently the phenyl substituent does not provide adequate stabilization of the carbene complex to allow its detection or isolation.
- Trace, Rhonda,Jones, W. M.
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- Hydride-Transfer Reaction to a Mononuclear Manganese(III) Iodosylarene Complex
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Metal iodosylarene species have received interest because of their potential oxidative power as a catalyst. We present the first example of hydride-transfer reactions to a mononuclear manganese(III) iodosylbenzene complex, [MnIII(TBDAP)(OIPh)(OH)]2+ (1; TBDAP = N,N-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane), with dihydronicotinamide adenine dinucleotide (NADH) analogues. Kinetic studies show that hydride-transfer from the NADH analogues to 1 occurs via a proton-coupled electron transfer, followed by a rapid electron transfer.
- Jeong, Donghyun,Cho, Jaeheung
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- PYRANO[4,3-B]L NDOLE DERIVATIVES AS ALPHA-1 -ANTITRYPSIN MODULATORS FOR TREATING ALPHA-1 -ANTITRYPSIN DEFICIENCY (AATD)
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Pyrano[4,3-b]indole derivatives as alpha-1-antitrypsin modulators for treating alpha-1-antitrypsin deficiency (AATD)
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Paragraph 00128-00129; 00216
(2021/10/11)
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- Synthesis method of cyclobutanone
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The invention provides a synthesis method of cyclobutanone. The method taking cyclopropanecarboxylic acid as a raw material comprises the following steps: reducing the raw material into cyclopropylmethanol, rearranging the cyclopropylmethanol under an acidic condition to obtain cyclobutanol, and carrying out TEMPO oxidation to obtain cyclobutanone. The method has the following advantages: the rawmaterials are cheap, the operation is simple, the total yield is high, and the product with the purity of 99% can be obtained through simple post-treatment. The method produces less three wastes and is suitable for large-scale production.
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Paragraph 0015; 0019; 0020
(2020/06/02)
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- Catalytic Selective Oxidation of Primary and Secondary Alcohols Using Nonheme [Iron(III)(Pyridine-Containing Ligand)] Complexes
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The selective oxidation of different primary and secondary alcohols to carbonyl compounds by hydrogen peroxide was found to be catalyzed in conversion ranging from good to excellent by an iron(III) complex of a pyridine-containing macrocyclic ligand (Pc-L), without the need of any additive. The choice of the counteranion (Cl, Br, OTf) appeared to be of fundamental importance and the best results in terms of selectivity (up to 99 %) and conversion (up to 98 %) were obtained using the well-characterized [Fe(III)(Br)2(Pc-L)]Br complex, 4c. Magnetic moments in solid-state, also confirmed in solution ([D6]DMSO) by Evans NMR method, were calculated and point out to an iron metal center in the high spin state of 5/2. The crystal structure shows that the iron(III) center is coordinated by the four nitrogen atoms of the macrocycle and two bromide anions to form a distorted octahedral coordination environment. The catalytic oxidation of benzyl alcohol in acetonitrile was found occurring with better conversions and selectivities than in other solvents. The reaction proved to be quite general, tolerating aromatic and aliphatic alcohols, although very low yields were obtained for terminal aliphatic alcohols. Preliminary mechanistic studies are in agreement with a catalytic cycle promoted by a high-spin iron complex.
- Caselli, Alessandro,Gallo, Emma,Panza, Nicola,Rizzato, Silvia,Tseberlidis, Giorgio,di Biase, Armando
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supporting information
p. 6635 - 6644
(2020/10/30)
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- Preparation method of cyclobutanone (by machine translation)
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The invention relates to the technical field of organic synthesis, in particular to a preparation method of cyclobutanone, which comprises the following steps: trichloroacetyl chloride is used for generating dichloroethylene ketone under the action of zinc powder and phosphorus oxychloride. The preparation method of the cyclobutanone provided by the invention is cheap and easily available in reaction raw materials, simple in reaction step, high in yield and good in industrial prospect. (by machine translation)
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Paragraph 0027; 0029-0030; 0032-0033; 0035
(2020/11/01)
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- Synthesis of trisubstituted alkenes by Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters
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A method for Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters was developed. The reaction has a broad substrate scope. This hydroalkylation shows excellent regio-and stereo-selectivity. This method enables readily available starting materials to be used to access a range of cyano-substituted single-configuration trisubstituted alkenes. These are valuable feedstock chemicals and are widely used in synthetic and medicinal chemistry.
- Lu, Xiao-Yu,Liu, Chuang-Chuang,Jiang, Run-Chuang,Yan, Lu-Yu,Liu, Qi-Le,Wang, Qing-Qing,Li, Jia-Mei
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supporting information
p. 14191 - 14194
(2020/11/24)
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- Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
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Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
- Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
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p. 782 - 792
(2019/01/03)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Aliphatic C-H Bond Halogenation by Iron(II)-α-Keto Acid Complexes and O2: Functional Mimicking of Nonheme Iron Halogenases
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α-Ketoglutarate-dependent nonheme halogenases catalyze the halogenation of aliphatic C-H bonds in the biosynthesis pathway of many natural products. An iron(IV)-oxo-halo species has been established as the active oxidant in the halogenation reactions. With an objective to emulate the function of the nonheme halogenases, two iron(II)-α-keto acid complexes, [(phdpa)Fe(BF)Cl] (1) and [(1,4-tpbd)Fe2(BF)2Cl2] (2) (where phdpa = N,N-bis(2-pyridylmethyl)aniline, 1,4-tpbd = N,N,N′,N'-tetrakis(2-pyridylmethyl)benzene-1,4-diamine, and BF = benzoylformate), have been prepared. The iron complexes are capable of carrying out the oxidative halogenation of aliphatic C-H bonds using O2 as the terminal oxidant. Although the complexes are not selective toward C-H bond halogenation, they are the only examples of nonheme iron(II)-α-keto acid complexes mimicking the activity of nonheme halogenases. The dinuclear complex (2) exhibits enhanced reactivity toward C-H bond halogenation/hydroxylation.
- Jana, Rahul Dev,Sheet, Debobrata,Chatterjee, Sayanti,Paine, Tapan Kanti
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supporting information
p. 8769 - 8777
(2018/08/17)
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- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
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Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
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supporting information
p. 10164 - 10167
(2018/09/13)
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- Copper-catalyzed tandem aerobic oxidative cyclization for the synthesis of 4-cyanoalkylpyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)pyrroles and cyclobutanone oxime esters
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A copper-catalyzed tandem ring-opening/cyclization reaction for the synthesis of 4-cyanoalkylpyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)pyrroles and cyclobutanone oxime esters has been developed. This reaction involves C-C bond cleavage and C-C and C-N bond constructions with good functional group tolerance. A wide range of products are obtained in moderate to good yields under mild conditions.
- An, Zhenyu,Jiang, Yong,Guan, Xin,Yan, Rulong
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supporting information
p. 10738 - 10741
(2018/09/29)
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- Manganese complex-catalyzed oxidation and oxidative kinetic resolution of secondary alcohols by hydrogen peroxide
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The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn-oxo species. Density functional theory calculations revealed the difference in reaction energy barriers for H-atom abstraction from the α-CH bonds of R- and S-enantiomers by a chiral high-valent manganese-oxo complex, supporting the experimental result from the OKR of secondary alcohols.
- Miao, Chengxia,Li, Xiao-Xi,Lee, Yong-Min,Xia, Chungu,Wang, Yong,Nam, Wonwoo,Sun, Wei
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p. 7476 - 7482
(2017/10/30)
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- A β-Carbon elimination strategy for convenient: In situ access to cyclopentadienyl metal complexes
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The electronic and steric properties of tailored cyclopentadienyl (Cp) ligands are powerful handles to modulate the catalytic properties of their metal complexes. This requires the individual preparation, purification and storage of each ligand/metal combination. Alternative, ideally in situ, complexation protocols would be of high utility. We disclose a new approach to access Cp metal complexes. Common metal precursors rapidly react with cyclopentadienyl carbinols via β-carbon eliminations to directly give the Cp-metal complexes. An advantage of this is the direct and flexible use of storable pre-ligands. No auxiliary base is required and the Cp complexes can be prepared in situ in the reaction vessel for subsequent catalytic transformations.
- Smits,Audic,Wodrich,Corminboeuf,Cramer
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p. 7174 - 7179
(2017/10/05)
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- Non-plasmonic metal nanoparticles as visible light photocatalysts for the selective oxidation of aliphatic alcohols with molecular oxygen at near ambient conditions
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Nanoparticles (NPs) of Pd and Pt were used for the selective oxidation of aliphatic alcohols with molecular oxygen as an oxidant at near ambient temperatures under visible light irradiation. Distinct final products were obtained under identical reaction conditions, aliphatic esters formed over the Pd NPs while aldehydes formed over the Pt NPs. The reason for this different product selectivity is proven to be due to the much stronger interaction of Pd NPs with alcohol and aldehyde compared to Pt NPs. The photocatalytic activity is tuneable by light intensity or a moderate change in the reaction temperature.
- Tana, Tana,Guo, Xiao-Wei,Xiao, Qi,Huang, Yiming,Sarina, Sarina,Christopher, Phillip,Jia, Jianfeng,Wu, Haishun,Zhu, Huaiyong
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p. 11567 - 11570
(2016/10/03)
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- Aerobic alcohol oxidation and oxygen atom transfer reactions catalyzed by a nonheme iron(II)-α-keto acid complex
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α-Ketoglutarate-dependent enzymes catalyze many important biological oxidation/oxygenation reactions. Iron(iv)-oxo intermediates have been established as key oxidants in these oxidation reactions. While most reported model iron(ii)-α-keto acid complexes exhibit stoichiometric reactivity, selective oxidation of substrates with dioxygen catalyzed by biomimetic iron(ii)-α-keto acid complexes remains unexplored. In this direction, we have investigated the ability of an iron(ii) complex [(TpPh,Me)FeII(BF)] (1) (TpPh,Me = hydrotris(3-phenyl-5-methylpyrazolyl)borate and BF = monoanionic benzoylformate) to catalyze the aerobic oxidation of organic substrates. An iron-oxo oxidant, intercepted in the reaction of 1 with O2, selectively oxidizes sulfides to sulfoxides, alkenes to epoxides, and alcohols to the corresponding carbonyl compounds. The oxidant from 1 is able to hydroxylate the benzylic carbon of phenylacetic acid to afford mandelic acid with the incorporation of one oxygen atom from O2 into the product. The iron(ii)-benzoylformate complex oxidatively converts phenoxyacetic acids to the corresponding phenols, thereby mimicking the function of iron(ii)-α-ketoglutarate-dependent 2,4-dichlorophenoxyacetate dioxygenase (TfdA). Furthermore, complex 1 exhibits catalytic aerobic oxidation of alcohols and oxygen atom transfer reactions with multiple turnovers.
- Sheet, Debobrata,Paine, Tapan Kanti
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p. 5322 - 5331
(2016/08/02)
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- Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile
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Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH3CN)62+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH3CN)62+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH3CN)62+] and [O3] and independent of [substrate] at concentrations greater than ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, kcat = (8 ± 1) × 104 M-1 s-1, and that for (C2H5)2O is (5 ± 0.5) × 104 M-1 s-1. In the absence of substrate, Fe(CH3CN)62+ reacts with O3 with kFe = (9.3 ± 0.3) × 104 M-1 s-1. The similarity between the rate constants kFe and kcat strongly argues for Fe(CH3CN)62+/O3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH3CN)62+/O3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. This assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.
- Bataineh, Hajem,Pestovsky, Oleg,Bakac, Andreja
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p. 1629 - 1637
(2015/03/14)
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- Catalytic oxidation of water and alcohols by a robust iron(III) complex bearing a cross-bridged cyclam ligand
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An iron(III) complex bearing a cross-bridged cyclam ligand (4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) is an efficient catalyst for the oxidation of both water and alcohols using sodium periodate as the oxidant. In catalytic water oxidation a maximum turnover number (TON) of 1030 is achieved, while in catalytic alcohol oxidation >95% conversions and yields can be obtained.
- Tan, Peng,Kwong, Hoi-Ki,Lau, Tai-Chu
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supporting information
p. 12189 - 12192
(2015/07/27)
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- Mechanistic elucidation of C-H oxidation by electron rich non-heme iron(IV)-oxo at room temperature
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Non-heme iron(iv)-oxo species form iron(iii) intermediates during hydrogen atom abstraction (HAA) from the C-H bond. While synthesizing a room temperature stable, electron rich, non-heme iron(iv)-oxo compound, we obtained iron(iii)-hydroxide, iron(iii)-alkoxide and hydroxylated-substrate-bound iron(ii) as the detectable intermediates. The present study revealed that a radical rebound pathway was operative for benzylic C-H oxidation of ethylbenzene and cumene. A dissociative pathway for cyclohexane oxidation was established based on UV-vis and radical trap experiments. Interestingly, experimental evidence including O-18 labeling and mechanistic study suggested an electron transfer mechanism to be operative during C-H oxidation of alcohols (e.g. benzyl alcohol and cyclobutanol). The present report, therefore, unveils non-heme iron(iv)-oxo promoted substrate-dependent C-H oxidation pathways which are of synthetic as well as biological significance.
- Rana, Sujoy,Dey, Aniruddha,Maiti, Debabrata
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supporting information
p. 14469 - 14472
(2015/09/28)
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- Mechanism of Alcohol Oxidation by FeV(O) at Room Temperature
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Selective oxidation of alcohol to its corresponding carbonyl compound is an important chemical process in biological as well as industrial reactions. The heme containing enzyme CytP450 has been known to selectively oxidize alcohols to their corresponding carbonyl compounds. The mechanism of this reaction, which involves high-valent FeIV(O)-porphyrin?+ intermediate with alcohol, has been well-studied extensively both with the native enzyme and with model complexes. In this paper, we report for the first time the mechanistic insight of alcohol oxidation with FeV(O) complex of biuret TAML (bTAML), which is isoelectronic with FeIV(O)-porphyrin?+ intermediate form in CytP450. The oxidations displayed saturation kinetics, which allowed us to determine both the binding constants and first-order rate constants for the reaction. The K and k values observed for the oxidation of benzyl alcohol by FeV(O) at room temperature (K = 300 M-1, k = 0.35 s-1) is very similar to that obtained by CytP450 compound I at -50 °C (K = 214 M-1, k = 0.48 s-1). Thermodynamic parameters determined from van't Hoff's plot (ΔH~ -4 kcal/mol) suggest hydrogen bonding interaction between substrate and bTAML ligand framework of the FeV(O) complex. Analysis of H/D KIE (kH/kD ~ 19 at 303 K), Hammett correlation and linearity in Bell-Evans-Polyanski plot points to the C-H abstraction as the rate determination step. Finally, experiments using FeV(O18) for benzyl alcohol oxidation and use of the "radical clock" cyclobutanol as a substrate shows the absence of a rebound mechanism as is observed for CytP450. Instead, an ET/PT process is proposed after C-H abstraction leading to formation of the aldehyde, similar to what has been proposed for the heme and nonheme model compounds.
- Ghosh, Munmun,Nikhil,Dhar, Basab B.,Sen Gupta, Sayam
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p. 11792 - 11798
(2015/12/30)
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- H2O2-oxidation of α-aminoisobutyric and cyclic amino acids catalyzed by iron(III) isoindoline complexes
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Series of dichloroiron(III) complexes of 1,3-bis(2′-arylimino)isoindoline have been used as catalysts for the oxidative decarboxylation and deamination reaction of acyclic [α-aminoisobutyric acid (AIBH)] and cyclic amino acids [1-aminocyclohexane-1-carboxylic acid (ACHH), 1-aminocyclopentane-1-carboxylic acid (ACPH), 1-aminocyclobutane-1-carboxylic acid (ACBH), 1-aminocyclopropane-1-carboxylic acid (ACCH)] to ethylene or the corresponding carbonyl compounds. We have found that the title complexes are very efficient and selective as catalysts, and linear correlations were observed between the reaction rate and the oxidation potential, E°′pa of the iron complexes, and the endocyclic bond angle of the substrates used.
- Lakk-Bogáth, Dóra,Harasztia, Miklós,Csonka, Róbert,Speier, Gábor,Kaizer, József
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- Chemoselective hydrogen peroxide oxidation of allylic and benzylic alcohols under mild reaction conditions catalyzed by simple iron-picolinate complexes
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Chemoselective oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds proceeded efficiently using hydrogen peroxide with iron-picolinate catalysts. The in situ generated [Fe(Me-Pic)3] (Me-Pic = 6-methylpicolinate) catalyzed oxidation of the alcohol moiety of primary allylic alcohols while the [Fe(Pic)3] (Pic = picolinate) and [Fe(Me-Pic)2(Pic)] did not show sufficient catalytic activity. the Partner Organisations 2014.
- Tanaka, Shinji,Kon, Yoshihiro,Nakashima, Takuya,Sato, Kazuhiko
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p. 37674 - 37678
(2014/11/07)
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- Chemoselective hydrogen peroxide oxidation of allylic and benzylic alcohols under mild reaction conditions catalyzed by simple iron-picolinate complexes
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Chemoselective oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds proceeded efficiently using hydrogen peroxide with iron-picolinate catalysts. The in situ generated [Fe(Me-Pic)3] (Me-Pic = 6-methylpicolinate) catalyzed oxidation of the alcohol moiety of primary allylic alcohols while the [Fe(Pic)3] (Pic = picolinate) and [Fe(Me-Pic)2(Pic)] did not show sufficient catalytic activity. This journal is
- Tanaka, Shinji,Kon, Yoshihiro,Nakashima, Takuya,Sato, Kazuhiko
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p. 37674 - 37678
(2014/12/11)
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- Oxidation of alcohols and activated alkanes with lewis acid-activated tempo
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The reactivity of MCl3(η1O) (M = Fe, 1; Al, 2; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) with a variety of alcohols, including 3,4-dimethoxybenzyl alcohol, 1-phenyl-2-phenoxyethanol, and 1,2-diphenyl-2-methoxyethanol, was investigated using NMR spectroscopy and mass spectrometry. Complex 1 was effective in cleanly converting these substrates to the corresponding aldehyde or ketone. Complex 2 was also able to oxidize these substrates; however, in a few instances the products of overoxidation were also observed. Oxidation of activated alkanes, such as xanthene, by 1 or 2 suggests that the reactions proceed via an initial 1-electron concerted proton-electron transfer (CPET) event. Finally, reaction of TEMPO with FeBr3 in Et2O results in the formation of a mixture of FeBr3(η1OH) (23) and [FeBr2(η1OH)]2(μ-O) (24), via oxidation of the solvent, Et2O.
- Nguyen, Thuy-Ai D.,Wright, Ashley M.,Page, Joshua S.,Wu, Guang,Hayton, Trevor W.
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p. 11377 - 11387
(2015/02/19)
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- Co(ii), a catalyst for selective conversion of phenyl rings to carboxylic acid groups
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An inexpensive protocol for the conversion of -C6H4R into -COOH groups using Co(ii)-Oxone mixture as the catalytic system is described. A series of substrates containing substituted and non-substituted phenyl groups could be selectively converted into carboxylic acids. Initial mechanistic data have been provided.
- Sinha, Shashi Bhushan,Campos, Jess,Brudvig, Gary W.,Crabtree, Robert H.
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p. 49395 - 49399
(2014/12/10)
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- Copper catalyzed oxidation of amino acids
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Copper(II) chloride and novel bis(1-amino(cyclo)alkane-1-carboxylato- κ2N,O)copper(II) complexes as catalysts were studied in relation with enzymatic oxidation of amino acids. The oxidation of aminophosphonate derivative: (1-amino-1-methyl)ethylphosphonic acid was also investigated. Two bis(1-aminocycloalkane-1-carboxylato-κ2N,O) copper(II) complexes were structurally characterized. Surprisingly, while the 1-aminocyclobutane-1-carboxylate complex has square planar (SP-4) copper(II) center with trans-orientated ligands, the 1-aminocyclohexane-1-carboxylate complex has μ-carboxylato dimeric structure with square pyramidal (SPY-5) sites, one with cis- and one with trans-orientated ligands. Redox behavior of the bis(1-amino(cyclo)alkane-1-carboxylato-κ2N,O)copper(II) complexes was also investigated. Catalytic oxidations were carried out in alkaline DMF-water mixtures using H2O2 as oxidant and the complexes as catalysts. The observed potentials for the irreversible current peaks associated with the Cu(II) to Cu(I) reduction and the rates of the amino acid oxidations show inverse trend. This suggests that the Cu(II)/Cu(I) redox cycling due to the presence of H2O2 plays important role in the peroxide/copper activation that in turn provides the observed products.
- Góger, Szabina,Pap, József S.,Bogáth, Dóra,Simaan, A. Jalila,Speier, Gábor,Giorgi, Michel,Kaizer, József
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- Ruthenium-catalyzed oxidation of alcohols by bromate in water
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The polypyridylruthenium(ii) complex, cis-[Ru(2,9-Me2phen) 2(OH2)2]2+, is a highly efficient catalyst for the oxidation of alcohols to carbonyl products in water using sodium bromate (NaBrO3) as the terminal oxidant. Excellent conversions and yields are readily achieved at room temperature.
- Hu, Zongmin,Ma, Li,Xie, Jianhui,Du, Hongxia,Lam, William W. Y.,Lau, Tai-Chu
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p. 1707 - 1710
(2013/07/05)
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- Bio-inspired amino acid oxidation by a non-heme iron catalyst
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This study reports the kinetics and mechanism of Fe(III)-catalyzed oxidative decarboxylation and deamination of a series of acyclic (α-aminoisobutyric acid, α-(methylamino)isobutyric acid, alanine, norvaline, and 2-aminobutyric acid) and cyclic (1-aminocyclopropane-1-carboxylic acid, 1-amino-1-cyclobutanecarboxylic acid, 1-aminocyclopentanecarboxylic acid, and 1-aminocyclohexanecarboxylicacid) amino acids using hydrogen peroxide, t-butyl hydroperoxide, iodosylbenzene, m-chloroperbenzoic acid, and peroxomonosulphate as oxidant in 75% DMF-25% water solvent mixture. Model complex [FeIVO(SALEN)]?+ (SALENH2: N,N′-bis(salicylidene)ethylenediamine) was generated by the reaction of FeIII(SALEN)Cl and H2O2 in CH3CN at 278 K as reported earlier. This method provided us high-valent oxoiron species, stable enough to ensure the direct observation of the reaction with amino acids.
- Góger, Szabina,Bogáth, Dóra,Baráth, Gábor,Simaan, A. Jalila,Speier, Gábor,Kaizer, József
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- Lewis acid-activated oxidation of alcohols by permanganate
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The oxidation of alcohols by KMnO4 is greatly accelerated by various Lewis acids. Notably the rate is increased by 4 orders of magnitude in the presence of Ca2+. The mechanisms of the oxidation of CH 3OH and PhCH(OH)CH3 by MnO4- and BF3·MnO4- have also been studied computationally by the DFT method.
- Du, Hongxia,Lo, Po-Kam,Hu, Zongmin,Liang, Haojun,Lau, Kai-Chung,Wang, Yi-Ning,Lam, William W. Y.,Lau, Tai-Chu
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supporting information; scheme or table
p. 7143 - 7145
(2011/09/12)
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- Alcohol oxidation catalysed by Ru(VI) in the presence of alkaline hexacyanoferrate(III)
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The oxidation of sodium lactate, 2-methyl-2,4-pentanediol, 2,4-butanediol, 2-butanol and 2-propanol upon treatment with alkaline hexacyanoferrate(III) using a Ru(VI) catalyst is highly effective for the oxidation of alcohols by Fe(CN)63-. The reaction mechanism proposed involves the oxidation of the alcohol by the catalyst, a process that occurs through the formation of a substrate-catalyst complex. The decomposition of this complex yields Ru(IV) and a carbocation (owing to a hydride transfer from the α-C-H bond of the alcohol to the oxoligand of ruthenium). The role of the co-oxidant, hexacyanoferrate(III), is to regenerate the catalyst. In the oxidation reactions, the rate constants for complex decomposition and catalyst regeneration have been determined and a comparative study of the structure versus reactivity has been carried out. Copyright
- Poblete, Francisco J.,Corrochano, Pablo
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experimental part
p. 1088 - 1092
(2011/07/06)
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- Mechanism of alcohol oxidation by dipicolinate vanadium(V): Unexpected role of pyridine
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Dipicolinate vanadium(V) alkoxide complexes (dipic)VV(O)(OR) (OR = isopropoxide (1), n-butanoxide (2), cyclobutanoxide (3), and α-tert-butylbenzylalkoxide (4)) react with pyridine to afford vanadium(IV) and 0.5 equiv of an aldehyde or ketone product. The role of pyridine in the reaction has been investigated. Both NMR and X-ray crystallography experiments indicate that pyridine coordinates to 1, which is in equilibrium with (dipic)VV(O)(OiPr)(pyr) (1-Pyr). Kinetic studies of the alcohol oxidation suggest a pathway where the rate-limiting step is bimolecular and involves attack of pyridine on the C-H bond of the isopropoxide ligand of 1 or 1-Pyr. The oxidations of mechanistic probes cyclobutanol and α-tert-butylbenzylalcohol support a two-electron pathway proceeding through a vanadium(III) intermediate. The alcohol oxidation reaction is promoted by more basic pyridines and facilitated by electron-withdrawing substituents on the dipicolinate ligand. The involvement of base in the elementary alcohol oxidation step observed for the dipicolinate system is an unprecedented mechanism for vanadium-mediated alcohol oxidation and suggests new ways to tune reactivity and selectivity of vanadium catalysts.
- Hanson, Susan K.,Baker, R. Tom,Gordon, John C.,Scott, Brian L.,Silks, L. A. Pete,Thorn, David L.
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experimental part
p. 17804 - 17816
(2011/02/25)
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- Ruthenium-functionalized nickel hydroxide catalyst for highly efficient alcohol oxidations in the presence of molecular oxygen
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Ru/Ni(OH)2 composite, prepared by simple wetness impregnation method, has demonstrated highly efficient alcohol oxidation reaction in the presence of molecular oxygen at T = 363 K with good selectivity (>99%) and excellent reaction yield (TOF ~ 132 h-1).
- Venkatesan,Senthil Kumar,Lee, Jyh-Fu,Chan, Ting-Shan,Zen, Jyh-Myng
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body text
p. 1912 - 1914
(2009/10/17)
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- Catalytic aerobic oxidation of allylic alcohols to carbonyl compounds under mild conditions
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A new catalytic aerobic oxidation of alcohols to aldehydes under green conditions was developed (room temperature and pressure, water solution, open vials). The water-soluble platinum(II) tetrasulfophthalocyanine (PtPcS) catalyst showed the best selectivity for carbonyl derivatives, and in particular for α,β-unsaturated alcohols; the reactions are slow.
- Tonucci, Lucia,Nicastro, Marco,D'Alessandro, Nicola,Bressan, Mario,D'Ambrosio, Primiano,Morvillo, Antonino
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experimental part
p. 816 - 820
(2010/04/23)
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- A thermodynamic study of ketoreductase-catalyzed reactions 2. Reduction of cycloalkanones in non-aqueous solvents
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The equilibrium constants for the ketoreductase-catalyzed reactions (cycloalkanone + 2-propanol = cycloalkanol + acetone) have been measured in n-hexane, n-pentane, and supercritical carbon dioxide SCCO2 (pressure = (8.0 to 12.0) MPa). The cycloalkanones included in this study were: cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone. The equilibrium constants for the reactions involving cyclobutanone and cyclohexanone were measured in n-hexane over the range T = (288.35 to 308.05) K. The thermodynamic quantities at T = 298.15 K are: K = (0.763 ± 0.001); ΔrGm=(0.670±0.002)kJ·mol-1; ΔrHm=-(1.09±0.11) kJ·mol-1, and ΔrSm=-(5.9±0.4)J·K-1·mol-1 for the reaction involving cyclobutanone; and K = (15.7 ± 0.2); ΔrGm=-(6.82±0.02)kJ·mol-1; ΔrHm=-(4.6±1.0) kJ·mol-1, and ΔrSm=(7.4±3.3)J·K-1·mol-1 for the reaction involving cyclohexanone, respectively. An inspection of the equilibrium constants for these reactions in n-hexane, n-pentane, and SCCO 2 shows that solvent dependence is not significant. The equilibrium constants of cycloalkanones decrease with increasing value of the number of carbons, NC with the exception of cyclohexanone. The cyclohexanol, which adopts a nearly strainless, idealized tetrahedral conformation around each carbon, is thermodynamically favored and more stable compared to other cycloalkanol rings, and this is reflected in the significantly higher value of the equilibrium constant obtained for this reaction. Comparisons with results obtained by using two independent thermochemical routes are also made.
- Tewari, Yadu B.,Phinney, Karen W.,Liebman, Joel F.
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p. 388 - 395
(2008/02/11)
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- Kinetics and mechanism of the oxidation of alcohols by tetrapropylammonium perruthenate
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2-Propanol is oxidized by tetrapropylammonium perruthenate (TPAP) in a reaction that is second order in TPAP and first order in 2-propanol. One of the products, believed to be ruthenium dioxide, is an effective catalyst for the reaction, making it an autocatalytic process. The rate of oxidation is relatively insensitive to the presence of substituents. Primary kinetic deuterium isotope effects are observed when either the hydroxyl or the α hydrogen is replaced by deuterium. The only product obtained from the oxidation of cyclobutanol is cyclobutanone, indicating that the reaction is a two-electron process. Tetrahydrofuran is oxidized at a rate that is several orders of magnitude slower than that observed for 2-propanol, suggesting that the reaction of TPAP with alcohols may be initiated by formation of perruthenate esters. A tentative mechanism consistent with these observations is proposed.
- Chandler, W. David,Wang, Zhao,Lee, Donald G.
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p. 1212 - 1221
(2007/10/03)
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- Salt-free preparation of cyclobutanone
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A salt-free process for preparing cyclobutanone, including isomerizing cyclopropylmethanol, preferably in aqueous solution, in the presence of an acidic heterogeneous catalyst to form cyclobutanol and, preferably after extraction and removal of the extractant, dehydrogenating the cyclobutanol over a heterogeneous catalyst.
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- Salt-free process for the production of cyclobutanone
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A process for the production of cyclobutanone comprises: (1) isomerization of cyclopropylmethanol to cyclobutanol in the presence of an acidic heterogeneous catalyst; and (2) dehydrogenation at a heterogeneous catalyst to form cyclobutanone.
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- Liquid phase oxygenation reaction using tungsten species
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The present invention is to provide a method by which, in carrying out a liquid-phase oxidation reaction using a catalyst comprising a tungsten species as an essential component, the catalytic activity performance can be improved or maintained and by which the catalyst component tungsten species can be prevented from being leached into liquid reaction mixtures to thereby control decrease in catalytic activity and make it possible to reuse the catalyst. A method of liquid-phase oxidation reaction using a tungsten species, wherein that, in carrying out said method of liquid-phase oxidation reaction using a catalyst comprising a tungsten species as an essential component, said tungsten species is caused to be supported on a porous support and, further, a third element other than the component elements of said porous support and the tungsten element is caused to coexist in said catalyst.
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- Scope, kinetics, and mechanistic aspects of aerobic oxidations catalyzed by ruthenium supported on alumina
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The Ru/Al2O3 catalyst was prepared by modification of the preparation of Ru(OH)3·nH2O. The present Ru/Al 2O3 catalyst has high catalytic activities for the oxidations of activated, nonactivated, and heterocyclic alcohols, diols, and amines at 1 atm of molecular oxygen. Furthermore, the catalyst could be reused seven times without a loss of catalytic activity and selectivity for the oxidation of benzyl alcohol. A catalytic reaction mechanism involving a ruthenium alcoholate species and β-hydride elimination from the alcoholate has been proposed. The reaction rate has a first-order dependence on the amount of catalyst, a fractional order on the concentration of benzyl alcohol, and a zero order on the pressure of molecular oxygen. These results and kinetic isotope effects indicate that β-elimination from the ruthenium alcoholate species is a rate-determining step.
- Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 4353 - 4361
(2007/10/03)
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- A new method for oxidation of various alcohols to the corresponding carbonyl compounds by using n-t-butylbenzenesulfinimidoyl chloride
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Various primary and secondary alcohols were smoothly oxidized to the corresponding aldehydes and ketones by using a new oxidizing agent, N-t-butylbenzenesulfinimidoyl chloride (4a), in the coexistence of DBU or zinc oxide. The present oxidation proceeded under mild conditions via five-membered intramolecular proton-transfer of an alkyl arenesulfinimidate intermediate.
- Matsuo, Jun-Ichi,Iida, Daisuke,Tatani, Kazuya,Mukaiyama, Teruaki
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p. 223 - 234
(2007/10/03)
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- Method of producing cyclobutanone
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The invention relates to a process for preparing cyclobutanone by oxidizing cyclobutanol with an alkali metal hypochlorite or alkaline earth metal hypochlorite in the presence of an acid.
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