- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
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Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
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- Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System
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Abstract: The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway. Graphic Abstract: [Figure not available: see fulltext.]
- Wang, Lingyao,Zhang, Yuanbin,Yuan, Haoran,Du, Renfeng,Yao, Jia,Li, Haoran
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p. 1663 - 1669
(2020/10/21)
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- Green Oxidation of Ketones to Lactones with Oxone in Water
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Cyclic ketones were quickly and quantitatively converted to 5-, 6-, and 7-membered lactones, very important synthons, by treatment with Oxone, a cheap, stable, and nonpollutant oxidizing reagent, in 1 M NaH2PO4/Na2HPO4 water solution (pH 7). Under such simple and green conditions, no hydroxyacid was formed, thus making the adoption of more complex and non-eco-friendly procedures previously developed to avoid lactone hydrolysis unnecessary. With some changes, the method was successfully applied also to water-insoluble ketones such as adamantanone, acetophenone, 2-indanone, and the challenging cycloheptanone.
- Bertolini, Valentina,Appiani, Rebecca,Pallavicini, Marco,Bolchi, Cristiano
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p. 15712 - 15716
(2021/11/01)
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- Revisiting Alkane Hydroxylation with m-CPBA (m-Chloroperbenzoic Acid) Catalyzed by Nickel(II) Complexes
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Mechanistic studies are performed on the alkane hydroxylation with m-CPBA (m-chloroperbenzoic acid) catalyzed by nickel(II) complexes, NiII(L). In the oxidation of cycloalkanes, NiII(TPA) acts as an efficient catalyst with a high yield and a high alcohol selectivity. In the oxidation of adamantane, the tertiary carbon is predominantly oxidized. The reaction rate shows first-order dependence on [substrate] and [NiII(L)] but is independent on [m-CPBA]; vobs=k2[substrate][NiII(L)]. The reaction exhibited a relatively large kinetic deuterium isotope effect (KIE) of 6.7, demonstrating that the hydrogen atom abstraction is involved in the rate-limiting step of the catalytic cycle. Furthermore, NiII(L) supported by related tetradentate ligands exhibit apparently different catalytic activity, suggesting contribution of the NiII(L) in the catalytic cycle. Based on the kinetic analysis and the significant effects of O2 and CCl4 on the product distribution pattern, possible contributions of (L)NiII?O. and the aroyloxyl radical as the reactive oxidants are discussed.
- Itoh, Mayu,Itoh, Shinobu,Kubo, Minoru,Morimoto, Yuma,Shinke, Tomoya,Sugimoto, Hideki,Wada, Takuma,Yanagisawa, Sachiko
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p. 14730 - 14737
(2021/09/29)
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- Aliphatic C–H hydroxylation activity and durability of a nickel complex catalyst according to the molecular structure of the bis(oxazoline) ligands
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Applicability of the oxazoline-based compounds, bis(2-oxazolynyl)methane (BOX) and 2,6-bis(2-oxazolynyl)pyridine (PyBOX), as supporting ligands of nickel(II) complexes for the catalysis of aliphatic C–H hydroxylation with m-CPBA (meta-chloroperoxybenzoic acid) was explored. Substituent groups at the fourth and fifth positions of oxazoline rings and the bridgehead carbon atom of the BOX derivatives affected the catalytic performances toward cyclohexane hydroxylation. Presence of dioxygen led to a reduced catalytic performance of the nickel complexes, except in the case of a fully substituted BOX ligand complex.
- Hikichi, Shiro,Izumi, Takashi,Matsuba, Naki,Nakazawa, Jun
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- Kinetics Modeling of a Convergent Cascade Catalyzed by Monooxygenase-Alcohol Dehydrogenase Coupled Enzymes
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A convergent cascade reaction coupling a cyclohexanone monooxygenase variant and an alcohol dehydrogenase to make ?-caprolactone from cyclohexanone and 1,6-hexanediol was characterized via progress curve analysis with two kinetic models developed iteratively. A chemical side reaction occurring with the utilized Tris buffer and consequent byproduct formations were considered in Model 2, which reduced the root-mean-square error (RMSE) values by half, compared to Model 1 (RMSE values of 13%-40%). The optimized model, Model 2, led us to simulate the cascade reaction including 22 kinetic parameters with a maximum RMSE value in the range of 10%-21%.
- Bornscheuer, Uwe T.,Engel, Jennifer,Kara, Selin
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supporting information
p. 411 - 420
(2020/12/22)
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- Method for preparing epsilon-caprolactone, 6-hydroxyhexanoic acid and esters thereof from tetrahydrofuranacetic acid and esters thereof
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The invention provides a method for preparing epsilon-caprolactone and 6-hydroxyhexanoic acid and esters thereof from tetrahydrofuranacetic acid and esters thereof, which comprises the following steps: in a solvent, in a reducing atmosphere and under the action of a catalyst, carrying out reduction reaction on tetrahydrofuranacetic acid and ester compounds thereof under the conditions that the pressure is 0.1-10MPa and the temperature is 20-200 DEG C for 0.5-48 hours, separating the catalyst, and distilling out the solvent, so that the target products epsilon-caprolactone, 6-hydroxyhexanoic acid and ester compounds of 6-hydroxyhexanoic acid are obtained. According to the method, efficient conversion of bio-based tetrahydrofuranacetic acid and esters thereof is realized under relatively mild conditions, the produced epsilon-caprolactone and 6-hydroxycaproic acid and ester compounds thereof are polymer monomers and are wide in application, and the application range of biomass is expanded; and meanwhile, the dilemma that the preparation of [epsilon]-caprolactone, 6-hydroxycaproic acid and ester thereof must depend on fossil resources is solved.
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Paragraph 0005; 0024
(2021/05/29)
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- A Polyketide Cyclase That Forms Medium-Ring Lactones
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Medium-ring lactones are synthetically challenging due to unfavorable energetics involved in cyclization. We have discovered a thioesterase enzyme DcsB, from the decarestrictine C1 (1) biosynthetic pathway, that efficiently performs medium-ring lactonizations. DcsB shows broad substrate promiscuity toward linear substrates that vary in lengths and substituents, and is a potential biocatalyst for lactonization. X-ray crystal structure and computational analyses provide insights into the molecular basis of catalysis.
- Gao, De-Wei,Jamieson, Cooper S.,Wang, Gaoqian,Yan, Yan,Zhou, Jiahai,Houk,Tang, Yi
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- PROCESS FOR PRODUCING HYDROXY ACID
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PROBLEM TO BE SOLVED: To provide a process for highly efficiently producing hydroxy acid from cyclic ketone. SOLUTION: Provided is a process for producing hydroxy acid, including a step in which hydrogen peroxide and cyclic ketone are reacted using water as solvent in the presence of a zeolite catalyst and a catalytic amount of organic acid. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0025-0027
(2020/05/13)
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- Ni(II) complexes of tripodal N4 ligands as catalysts for alkane hydroxylation and O-arylation of phenol: Structural and reactivity effects induced by fluoro substitution
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Nickel(II) complexes [NiII(L1-2)(OAc)(H2O)][BPh4] (1–2) and [NiII(L3)(OAc)][BPh4] (3) derived from fluorinated tripodal ligands viz. N-((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L1 or FTPA), N,N′-bis((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)methanamine (L2 or F2TPA) and tris((6-fluoropyridin-2-yl)methyl)amine (L3 or F3TPA) have been synthesized and characterized by spectroscopic (UV–visible, FT-IR, paramagnetic NMR), elemental analysis, electrochemistry and X-ray diffraction techniques. In structurally similar complexes 1 and 2, Ni(II) center has a distorted octahedral coordination geometry constituted by all the four N atoms of the ligands, one acetate group and a water molecule. Complex 3 has different structural aspects. It does not have the water molecule in the coordination sphere and contains one acetate group bound with metal center in a bidentate mode. All the complexes exhibit a one-electron oxidation corresponding to the NiII/NiIII redox couple, the potential of which is influenced by the donor functionalities of ligand. These complexes catalyze the oxidation of cyclohexane efficiently (turn over number: 586–698) and selectively (alcohol to ketone ratio: 7.9:1 to 8.4:1). The study also includes the catalysis of adamantane oxidation to a mixture of ketones and alcohols. Catalytic potential of all the three complexes (1–3) has also been screened for C–O coupling reactions of phenol with aryl halides. Among them, complex 1 is more efficient than 2 and 3 for such reactions.
- Kerbib, Wissame,Kumar, Arun,Kumar, Sushil,Nautiyal, Divyanshu,Singh, Siddhant
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- Efficient alkane hydroxylation catalysis of nickel(ii) complexes with oxazoline donor containing tripodal tetradentate ligands
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Tris(oxazolynylmethyl)amine TOAR(where R denotes the substituent groups on the fourth position of the oxazoline rings) complexes of nickel(ii) have been synthesized as catalyst precursors for alkane oxidation withmeta-chloroperoxybenzoic acid (m-CPBA). The molecular structures of acetato, nitrato,meta-chlorobenzoato and chlorido complexes with TOAMe2have been determined using X-ray crystallography. The bulkiness of the substituent groups R affects the coordination environment of the nickel(ii) centers, as has been demonstrated by comparison of the molecular structures of chlorido complexes with TOAMe2and TOAtBu. The nickel(ii)-acetato complex with TOAMe2is an efficient catalyst precursor compared with the tris(pyridylmethyl)amine (TPA) analogue. Oxazolynyl donors’ strong s-electron donating ability will enhance the catalytic activity. Catalytic reaction rates and substrate oxidizing position selectivity are controlled by the structural properties of the R of TOAR. Reaction of the acetato complex with TOAMe2andm-CPBA yields the corresponding acylperoxido species, which can be detected using spectroscopy. Kinetic studies of the decay process of the acylperoxido species suggest that the acylperoxido species is a precursor of an active species for alkane oxidation.
- Hikichi, Shiro,Horii, Sena,Nakazawa, Jun,Okamura, Masaya,Terao, Ikumi
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supporting information
p. 6108 - 6118
(2020/05/25)
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- Mechanism of Ni-catalyzed oxidations of unactivated C(sp3)-H Bonds
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The Ni-catalyzed oxidation of unactivated alkanes, including the oxidation of polyethylenes, by meta-chloroperbenzoic acid (mCPBA) occur with high turnover numbers under mild conditions, but the mechanism of such transformations has been a subject of debate. Putative, high-valent nickel-oxo or nickel-oxyl intermediates have been proposed to cleave the C-H bond, but several studies on such complexes have not provided strong evidence to support such reactivity toward unactivated C(sp3)-H bonds. We report mechanistic investigations of Ni-catalyzed oxidations of unactivated C-H bonds by mCPBA. The lack of an effect of ligands, the formation of carbon-centered radicals with long lifetimes, and the decomposition of mCPBA in the presence of Ni complexes suggest that the reaction occurs through free alkyl radicals. Selectivity on model substrates and deuterium-labeling experiments imply that the m-chlorobenzoyloxy radical derived from mCPBA cleaves C-H bonds in the alkane to form an alkyl radical, which subsequently reacts with mCPBA to afford the alcohol product and regenerate the aroyloxy radical. This free-radical chain mechanism shows that Ni does not cleave the C(sp3)-H bonds as previously proposed; rather, it catalyzes the decomposition of mCPBA to form the aroyloxy radical.
- Qiu, Yehao,Hartwig, John F.
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supporting information
p. 19239 - 19248
(2020/11/13)
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- Preparation method of lactone compound
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The invention relates to a preparation method of a lactone compound. In the presence of an organic nitroxide radical precursor, an alcohol, and a Sn-based catalyst, a ketone represented by a formula (1) is oxidized with molecular oxygen to obtain a compound represented by a formula (2), wherein the organic nitroxide radical precursor is a nitrogen-containing cyclic compound having a skeleton represented by formula (I), in the formula (1), Ra and Rb are the same or different, and Ra and Rb are bonded to each other and form a ring together with an adjacent carbonyl carbon atom; in the formula (I), R represents a protective group of a hydroxyl group or a hydrogen atom; in the formula (2), Ra and Rb are the same or different, and Ra and Rb are bonded to each other and form a ring together withan adjacent carbonyl carbon atom and oxygen atom.
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-
Page/Page column 15-23
(2020/03/05)
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- (Cyclopentadienone)iron-Catalyzed Transfer Dehydrogenation of Symmetrical and Unsymmetrical Diols to Lactones
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Air-stable iron carbonyl compounds bearing cyclopentadienone ligands with varying substitution were explored as catalysts in dehydrogenative diol lactonization reactions using acetone as both the solvent and hydrogen acceptor. Two catalysts with trimethylsilyl groups in the 2- A nd 5-positions, [2,5-(SiMe3)2-3,4-(CH2)4(δ4-C4C= O)]Fe(CO)3 (1) and [2,5-(SiMe3)2-3,4-(CH2)3(δ4-C4C= O)]Fe(CO)3 (2), were found to be the most active, with 2 being the most selective in the lactonization of diols containing both primary and secondary alcohols. Lactones containing five-, six-, and seven-membered rings were successfully synthesized, and no over-oxidations to carboxylic acids were detected. The lactonization of unsymmetrical diols containing two primary alcohols occurred with catalyst 1, but selectivity was low based on alcohol electronics and modest based on alcohol sterics. Evidence for a transfer dehydrogenation mechanism was found, and insight into the origin of selectivity in the lactonization of 1°/2° diols was obtained. Additionally, spectroscopic evidence for a trimethylamine-ligated iron species formed in solution during the reaction was discovered.
- Tang, Yidan,Meador, Rowan I. L.,Malinchak, Casina T.,Harrison, Emily E.,McCaskey, Kimberly A.,Hempel, Melanie C.,Funk, Timothy W.
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p. 1823 - 1834
(2020/02/04)
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- Method for preparing epsilon-caprolactone by using in-situ peroxide
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The invention discloses a method for preparing epsilon-caprolactone by using in-situ peroxide. The method efficiently utilizes an in-situ peroxide obtained in a process of oxidizing alcohol by oxygento oxidize cyclohexanone into epsilon-caprolactone, i.e., under the catalysis of a catalyst, an alcohol is oxidized into the corresponding ketone while substances such as peroxy hydroxyl or hydrogen peroxide and the like generated in the process are fully utilized, so that the Baeyer Villiger oxidation reaction from cyclohexanone to epsilon-caprolactone is realized. Compared with a previous epsilon-caprolactone synthesis method, the method of the invention has the advantages that the product yield is remarkably increased, the use efficiency of alcohol is further improved, raw materials and reagents are cheap and easy to obtain, operation is easy, reaction conditions are mild, and the method is clean and environmentally friendly.
- -
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Paragraph 0056-0058
(2020/12/30)
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- A sustainable synthetic route for biobased 6-hydroxyhexanoic acid, adipic acid and ?-caprolactone by integrating bio- And chemical catalysis
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A green route for the production of 6-carbon polymer building blocks 6-hydroxyhexanoic acid, adipic acid and ?-caprolactone from 1,6-hexanediol, a hydrogenation product of biobased 5-hydroxymethylfurfural is reported. Gluconobacter oxydans oxidized 1,6-hexanediol completely to adipic acid, and selectively at pH 6-7 to 6-hydroxyhexanoic acid, which was converted to ?-caprolactone by catalytic cyclization. This journal is
- Hatti-Kaul, Rajni,Park, Ji Hoon,Pyo, Sang-Hyun,Srebny, Vanessa
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supporting information
p. 4450 - 4455
(2020/08/10)
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- ε-Caprolactone manufacture via efficient coupling Baeyer-Villiger oxidation with aerobic oxidation of alcohols
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To avoid the use of peracids oxidant or highly concentrated hydrogen peroxide which is potentially hazardous and explosive, herein, a new route to ε-caprolactone was developed in which molecule oxygen was employed as the terminal oxidant. The commercial available N-hydroxyphthalimide and ammonium cerium nitrate were used as the key catalysts for the increased yield of ε-caprolactone. For instance, the selectivity of ε-caprolactone was obtained 92 % with 85 % conversion of cyclohexanone which was comparable to the strategies using highly concentrated hydrogen peroxide. The sacrificed alcohols were transformed into corresponding ketones which were also valuable chemicals. Furthermore, the efficiency of the alcohols was achieved to unprecedented 52 %. The Baeyer-Villiger oxidation of various other cycloalkanones was also examined. The substituent group effect on the efficiency of sacrificed alcohols was investigated in which weak electron-donating substituent induced nearly quantitative yield of ε-caprolactone. The reaction mechanism was studied with the help of electron paramagnetic resonance which indicated the existence of a radical pathway.
- Du, Renfeng,Li, Haoran,Wang, Yongtao,Yao, Jia,Yuan, Haoran,Zhao, Chenxuan
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- Tin and copper species dispersed on a metal-organic framework as a new catalyst in aerobic Baeyer-Villiger oxidation: An insight into the mechanism
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Metal-organic frameworks (MOF) containing tin and copper metal salts were used as catalysts in the Baeyer-Villiger oxidation of cyclohexanone. The outcome was a synergistic effect on the catalyst's efficiency, which resulted from the simultaneous presence of copper and tin species in the MOF. The catalyst with high metal content showed the intermolecular dehydration of benzoic acid and the formation of benzoic anhydride in a side reaction as well as the Baeyer-Villiger oxidation reaction with a decline in efficiency. The optimized catalyst promoted the Baeyer-Villiger reaction in a high yield without the formation of benzoic anhydride.
- Alavijeh, Masoumeh Karimi,Amini, Mostafa M.
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- Soluble asphaltene oxide: A homogeneous carbocatalyst that promotes synthetic transformations
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Carbocatalysts, materials which are predominantly composed of carbon and catalyze the synthesis of organic or inorganic compounds, are promising alternatives to metal-based analogues. Even though current carbocatalysts have been successfully employed in a broad range of synthetic transformations, they suffer from a number of drawbacks in part due to their heterogeneous nature. For example, the insolubility of prototypical carbocatalysts, such as graphene oxide (GO), may restrict access to catalytically-active sites in a manner that limits performance and/or challenges optimization. Herein we describe the preparation and utilization of soluble asphaltene oxide (sAO), which is a novel material that is composed of oxidized polycyclic aromatic hydrocarbons and is soluble in a wide range of organic solvents as well as in aqueous media. sAO promotes an array of synthetically useful transformations, including esterifications, cyclizations, multicomponent reactions, and cationic polymerizations. In many cases, sAO was found to exhibit higher catalytic activities than its heterogeneous analogues and was repeatedly and conveniently recycled, features that were attributed to its ability to form homogeneous phases.
- Bielawski, Christopher W.,Jung, Hyosic
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p. 15598 - 15603
(2020/05/05)
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- Combining Photo-Organo Redox- and Enzyme Catalysis Facilitates Asymmetric C-H Bond Functionalization
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In this study, we combined photo-organo redox catalysis and biocatalysis to achieve asymmetric C–H bond functionalization of simple alkane starting materials. The photo-organo catalyst anthraquinone sulfate (SAS) was employed to oxyfunctionalise alkanes to aldehydes and ketones. We coupled this light-driven reaction with asymmetric enzymatic functionalisations to yield chiral hydroxynitriles, amines, acyloins and α-chiral ketones with up to 99 % ee. In addition, we demonstrate functional group interconversion to alcohols, esters and carboxylic acids. The transformations can be performed as concurrent tandem reactions. We identified the degradation of substrates and inhibition of the biocatalysts as limiting factors affecting compatibility, due to reactive oxygen species generated in the photocatalytic step. These incompatibilities were addressed by reaction engineering, such as applying a two-phase system or temporal and spatial separation of the catalysts. Using a selection of eleven starting alkanes, one photo-organo catalyst and 8 diverse biocatalysts, we synthesized 26 products and report for the model compounds benzoin and mandelonitrile > 97 % ee at gram scale.
- Zhang, Wuyuan,Fueyo, Elena Fernandez,Hollmann, Frank,Martin, Laura Leemans,Pesic, Milja,Wardenga, Rainer,H?hne, Matthias,Schmidt, Sandy
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- Method for preparing lactone compound by cycloalkane compound through oxidation
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The invention discloses a method for preparing a lactone compound by a cycloalkane compound through oxidation. The method comprises the following steps of using the cycloalkane compound as the raw material, and further oxidizing by a catalysis system under the oxygen-containing atmosphere, so as to obtain the lactone compound, wherein the catalysis system comprises a catalyst and an additive; thecatalyst is selected from a cyclic organic nitrogen and oxygen free radical precursor in formulas (I), (II), (III) and (IV); in the formula, R1, R2 and R3 are independently selected from hydrogen atom, alkyl, cycloalkyl, aryl, heterocycle, hydroxyl, nitryl, or halogen, or at least two of R1, R2 and R3 form loops; the additive is selected from an aldehyde compound. The preparation method has the advantages that the corresponding lactone is prepared by the cycloalkane compound through a one-step method; the conditions are mild, the safety is high, and the metal catalytic oxidization is avoided;the selectivity of the target product, namely the lactone compound, is high. The formulae are shown in the description.
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Paragraph 0091; 0092; 0097-0099
(2019/02/04)
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- Selective One-Step Aerobic Oxidation of Cyclohexane to ?-Caprolactone Mediated by N-Hydroxyphthalimide (NHPI)
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The selective one-step aerobic oxidation of cyclohexane to ?-caprolactone was achieved in the presence of N-hydroxyphthalimide (NHPI) and aldehyde under mild conditions. Remarkably, 12 % of cyclohexane was converted with a selectivity of 77 % of ?-caprolactone and 15 % of KA oil. Control experiments indicated that NHPI accelerated the oxidation of aldehydes and peroxy radicals generated from aldehydes in situ were the key intermediates in the period of CH bond activation. 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO) addition and a series of m-chloroperoxybenzoic acid (m-CPBA) oxidation experiments showed that the oxidation proceeded via a complex radical chain mechanism.
- Wang, Lingyao,Zhang, Yuanbin,Du, Renfeng,Yuan, Haoran,Wang, Yongtao,Yao, Jia,Li, Haoran
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p. 2260 - 2264
(2019/04/10)
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- Oxidation of KA oil to caprolactone with molecular oxygen using N-hydroxyphthalimide-mediated Ce(NH4)2(NO3)6 catalyst
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In traditional Baeyer-Villiger oxidation, peracids or hydrogen peroxide are usually adopted as the oxidants. When molecular oxygen is used as oxidant, the sacrificial agents are always indispensable, such as aldehydes that are transformed into cheap acids after reaction. In this work, KA oil (the industrial raw material, a mixture of cyclohexanol and cyclohexanone) has been oxidized to caprolactone by molecular oxygen using N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) as catalyst, in which the sacrificial agent is cyclohexanol, and it is converted into cyclohexanone, then into caprolactone rather than into byproducts. The selectivity of caprolactone was 98% with cyclohexanol conversion of 34% and it was still kept at 90% when the conversion reached to 46%. The mechanism investigation showed a bifunctional role of CAN, which performed both as a radical initiator for cyclohexanol oxidation and a Lewis acid for Baeyer-Villiger reaction. In the Baeyer-Villiger oxidation, a weak interaction between cerium and cyclohexanone was suggested by Fourier Transform Infrared Spectroscopy (FTIR), meanwhile, the active species generated from cerium and hydrogen peroxide was separated and characterized by FTIR. The detailed research also revealed an unusual effect between cerium and the Br?nsted acid generated as a byproduct, which was critical for caprolactone synthesis.
- Du, Renfeng,Yuan, Haoran,Yao, Jia,Li, Haoran
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- Heteroleptic cobalt(iii) acetylacetonato complexes with N-heterocyclic carbine-donating scorpionate ligands: Synthesis, structural characterization and catalysis
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Exposure of O2 to a reaction mixture containing bis(acac)cobalt(ii), a facially capping tris(N-heterocyclic carbene)borate ligand and 1-methylimidazole yields a heteroleptic cobalt(iii) complex with acac, 1-methylimidazole and tris(NHC)borate ligands. meta-Chloroperbenzoic acid is efficiently activated by this heteroleptic complex to catalytically oxidize cyclohexane at ambient temperature.
- Nishiura, Toshiki,Takabatake, Asako,Okutsu, Mariko,Nakazawa, Jun,Hikichi, Shiro
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supporting information
p. 2564 - 2568
(2019/02/27)
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- METHOD FOR PRODUCING ε-CAPROLACTONE
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A method for manufacturing andepsi;-caprolactone of the present invention comprises steps of converting adipic acid to 1,6-hexanediol and ring-closing 1,6-hexanediol to andepsi;-caprolactone. The method for manufacturing andepsi;-caprolactone of the present invention comprises steps of: converting adipic acid to 1,6-hexanediol; partially oxidizing the 1,6-hexanediol to 6-hydroxycaproic acid; and ring-closing 6-hydroxycaproic acid into andepsi;-caprolactone. The present process provides a novel approach for the synthesis of andepsi;-caprolactone with a high yield and selectivity.COPYRIGHT KIPO 2020
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- Study on Synthesis of Acid-Washed Illite Supported Fe3O4 Nanometer Catalyst and Baeyer–Villiger Oxidation Reaction of Cyclohexanone
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Baeyer–Villiger oxidation allows for effective control of the stereochemical structure of the product, which is a significant feature for functional group conversion and ring expansion in organic synthesis. In this study, Fe3O4 nanoparticles were loaded on acid-washed porous illite silicon slag (I-SR) using an in situ hydrothermal method to obtain the magnetic composite Fe3O4@I-SR. This composite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 adsorption–desorption isotherm measurements, vibrating sample magnetometer analysis, etc. The results indicated that the Fe3O4 nanoparticles had a face-centered cubic lattice geometry with an average size of about 10?nm; the nanoparticles were uniformly dispersed on the surface of the carrier (I-SR) and exhibited strong paramagnetism. Fe3O4@I-SR composite was found to be a promising and efficient catalyst with high activity (> 99% cyclohexanone conversion and > 99% ε-caprolactone selectivity) for the Baeyer–Villiger of cyclohexanone to ε-caprolactone. The catalyst could be easily separated from the reaction mixture and reused many times. Thus, Fe3O4@I-SR is an attractive multiphase catalyst that is easy to handle and recycle under environmentally friendly reaction conditions. Graphical Abstract: [Figure not available: see fulltext.].
- Yang, Yong,Guan, Dongdong,Liu, Yu,Chen, Shuang,Meng, Wan,Jiang, Nanzhe
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p. 1111 - 1117
(2019/02/13)
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- Method for preparing epsilon-caprolactone by catalyzing cyclohexanone oxidation through Fe2O3/CeO2
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The invention discloses a method for preparing epsilon-caprolactone by catalyzing cyclohexanone oxidation through Fe2O3/CeO2. The method comprises the following steps: with cyclohexanone as a raw material, oxygen as an oxidant and a Fe2O3/CeO2 composite oxide as a catalyst, adding a certain amount of co-oxidant and solvent, and conducting reacting at 30-70 DEG C for 1-5 hours to prepare the epsilon-caprolactone. The method has the advantages that the catalyst is simple to prepare and low in cost; under mild reaction conditions, the conversion rate of cyclohexanone can reach 99% or above, and the selectivity reaches 99% or above; and the catalyst can still maintain high catalytic activity after being repeatedly used for many times, and is high in stability.
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Paragraph 0020-0036
(2019/07/01)
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- Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
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Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
- Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
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supporting information
p. 14499 - 14503
(2019/09/17)
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- What to sacrifice? Fusions of cofactor regenerating enzymes with Baeyer-Villiger monooxygenases and alcohol dehydrogenases for self-sufficient redox biocatalysis
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A collection of fusion biocatalysts has been generated that can be used for self-sufficient oxygenations or ketone reductions. These biocatalysts were created by fusing a Baeyer-Villiger monooxygenase (cyclohexanone monooxygenase from Thermocrispum municipale: TmCHMO) or an alcohol dehydrogenase (alcohol dehydrogenase from Lactobacillus brevis: LbADH) with three different cofactor regeneration enzymes (formate dehydrogenase from Burkholderia stabilis: BsFDH; glucose dehydrogenase from Sulfolobus tokodaii: StGDH, and phosphite dehydrogenase from Pseudomonas stutzeri: PsPTDH). Their tolerance against various organic solvents, including a deep eutectic solvent, and their activity and selectivity with a variety of substrates have been studied. Excellent conversions and enantioselectivities were obtained, demonstrating that these engineered fusion enzymes can be used as biocatalysts for the synthesis of (chiral) valuable compounds.
- Mourelle-Insua, ángela,Aalbers, Friso S.,Lavandera, Iván,Gotor-Fernández, Vicente,Fraaije, Marco W.
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p. 1832 - 1839
(2019/02/24)
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- Continuous Flow Chemo-Enzymatic Baeyer-Villiger Oxidation with Superactive and Extra-Stable Enzyme/Carbon Nanotube Catalyst: An Efficient Upgrade from Batch to Flow
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Continuous flow chemo-enzymatic Baeyer-Villiger oxidation in the presence of exceptionally active Candida antarctica lipase B immobilized via simple physical adsorption on multiwalled carbon nanotubes has been investigated. The nanobiocatalyst was used to generate peracid in situ from ethyl acetate and 30 wt % aq. hydrogen peroxide as the primary oxidant. Application of the highly stable and active nanobiocatalyst in the Baeyer-Villiger oxidation of 2-methylcyclohexanone to 6-methyl-?-caprolactone after 8 h at 40 °C led to a high product yield (87%) and selectivity (>99%). Environmentally friendly ethyl acetate was applied as both solvent and the peracid precursor. To determine the most favorable reaction conditions, a series of experiments using various parameters was performed. The main contribution of this work is that it describes the first application of the nanobiocatalyst in a chemo-enzymatic Baeyer-Villiger oxidation in a flow system. Since the process was performed in a flow reactor, many improvements were achieved. First of all, substantially shorter reaction times as well as a significant increase in the product yield were obtained as compared to the batch process. Since peracids are unstable, a large increase in the safety of the process was demonstrated under mild conditions in this work. In summary, this work shows a particularly efficient upgrade in the studied processes by transfer from a batch to a flow system.
- Szelwicka, Anna,Zawadzki, Przemys?aw,Sitko, Magdalena,Boncel, S?awomir,Czardybon, Wojciech,Chrobok, Anna
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supporting information
p. 1386 - 1395
(2019/08/12)
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- Combined H2O2/nitrile/bicarbonate system for catalytic Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone over Mg–Al hydrotalcite catalysts
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Magnesium-aluminium hydrotalcite-like compounds (Ht) with molar ratios of Mg/Al = 2, 3, 4 and 6, were synthesized and used as catalysts in the Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone. Oxidation was carried out in mild conditions (70 °C, atmospheric pressure) either with conventional H2O2/acetonitrile oxidizing mixture, or with a newly designed H2O2/acetonitrile/bicarbonate system. The presented results show clearly superiority of bicarbonate-containing setup, which provides a significant increase of the ε-caprolactone yield. The neutralizing effect of bicarbonate, strongly limiting leaching of magnesium from Ht, is considered the main cause of the improved catalytic performance.
- Karcz, Robert,Olszówka, Joanna E.,Napruszewska, Bogna D.,Kry?ciak-Czerwenka, Joanna,Serwicka, Ewa M.,Klimek, Agnieszka,Bahranowski, Krzysztof
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- METHOD FOR PRODUCING COMPOSITION DERIVED FROM ESTER COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing a composition derived from an ester compound useful as a raw material such as a polyester. SOLUTION: There is provided a method for producing a composition derived from an ester compound which is composed of an ester compound represented by the following formula (3), carboxylic acid derived from the ester compound and an alcohol compound or the like by reacting a ketone compound represented by the following formula (1), a peroxide such as hydrogen peroxide and a metal compound such as tin tetrachloride in an organic solvent such as trifluoro-ethanol represented by R3-OH. [R1 and R2 each independently represents H or an alkyl group having 1 to 8 carbon atoms; R1 and R2 may be bonded together to form a ring.] SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0082; 0083; 0084; 0085; 0086; 0087; 0088-0092
(2019/05/17)
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- An Alcohol Dehydrogenase from the Short-Chain Dehydrogenase/Reductase Family of Enzymes for the Lactonization of Hexane-1,6-diol
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Biocatalytic production of lactones, and in particular ?-caprolactone (CL), have gained increasing interest as a greener route to polymer building blocks, especially through the use of Baeyer–Villiger monooxygenases (BVMOs). Despite several advances in the field, BVMOs, however, still suffer several practical limitations. Alcohol dehydrogenase (ADH)-mediated lactonization of diols in turn has received far less attention and very few enzymes have been identified for the conversion of diols to lactones, with horse-liver ADH (HLADH) remaining the catalyst of choice. Screening of a diverse panel of ADHs, AaSDR-1, a member of the short-chain dehydrogenase/reductase family, was found to produce ?-caprolactone from hexane-1,6-diol. Moreover, cofactor regeneration by an NADH oxidase eliminated the requirement of co-substrates, yielding water as the sole by-product. Despite lower turnover frequencies as compared to HLADH, higher selectivity was found for the production of CL, with HLADH forming significant amounts of 6-hydroxyhexanoic acid and adipic acid through aldehyde dehydrogenation/oxidation of the gem-diol intermediates. Also, CL yield were shown to be dependent on buffer choice, as structural elucidation of a Tris adduct confirmed the buffer amine to react with aliphatic aldehydes forming a Schiff-base intermediate which through further ADH oxidation, forms a tricyclic acetal product.
- Dithugoe, Choaro D.,van Marwijk, Jacqueline,Smit, Martha S.,Opperman, Diederik J.
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- Preparation method of 11- andrographolide compound and caprolactone compound (by machine translation)
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To the method, cyclohexenone spiro-11 - peroxide is used as a raw material, a protic acid is used as a catalyst, fluorine alcohol is used as a solvent, and the reaction temperature is in a range of from 25 °C~60 °C about. The method has the advantages of high yield, low cost, convenience in operation, mild reaction conditions and the like, and is convenient for industrial application. (by machine translation)
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Paragraph 0046-0070; 0075-0078
(2019/11/28)
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- Highly Selective Silica-supported Copper Catalysts Derived from Copper Phyllosilicates in the Hydrogenation of Adipic Acid to 1,6-hexanediol
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Hydrogenation of adipic acid (AA) is a potential way to prepare 1,6-hexanediol (HDOL). Herein, silica-supported copper catalysts derived from copper phyllosilicates were synthesized, characterized, and tested in the hydrogenation of AA to HDOL. In a full conversion of AA, a high yield of HDOL (approximately 90 %) was obtained through the use of each Cu-based catalyst. The turnover frequency calculated according to the consumption rate of AA was discovered to be dependent on the Cu+/(Cu0+Cu+) ratio and the reduction condition. Moreover, recycling tests showed that a catalyst derived from a copper phyllosilicate had better stability compared with Cu/SiO2 made through impregnation due to a stronger interaction between Cu and silica. The kinetic analyses based on the global rate expression and Langmuir?Hinshelwood?Hougen?Watson (LHHW) formalism of AA conversion were conducted. The possible competitive adsorption between AA and its derivatives, including hydroxycaproic acid and ?-caprolactone, was thereby revealed.
- Jiang, Jia-Wei,Tu, Cheng-Chieh,Chen, Chao-Huang,Lin, Yu-Chuan
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p. 5449 - 5458
(2018/12/04)
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- Cobalt(II) complexes with N,N,N-scorpionates and bidentate ligands: Comparison of hydrotris(3,5-dimethylpyrazol-1-yl)borate Tp? vs. Phenyltris(4,4-dimethyloxazolin-2-yl)borate ToM to control the structural properties and reactivities of cobalt centers
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Scorpionate ligands Tp? (hydrotris(3,5-dimethylpyrazol-1-yl)borate) and ToM (tris(4,4- dimethyloxazolin-2-yl)phenylborate) complexes of cobalt(II) with bidentate ligands were synthesized. Both Tp? and ToM coordinate to cobalt(II) in a tridentate fashion when the bidentate ligand is the less hindered acetylacetonate. In crystal structures, the geometry of cobalt(II) supported by the N3O2 donor set in the Tp? complex is a square-pyramid, whereas that in the ToM complex is close to a trigonal-bipyramid. Both Tp?- and ToM-acac complexes exhibit solvatochromic behavior, although the changing structural equilibria of these complexes in MeCN are quite different. In the bis(1-methylimidazol-2-yl)methylphenylborate (LPh) complexes, Tp? retains the tridentate (k3) mode, whereas ToM functions as the bidentate (k2) ligand, giving the tetrahedral cobalt(II) complex. The bowl-shaped cavity derived from the six methyl groups on ToM lead to susceptibility to the bulkiness of the opposite bidentate ligand. The entitled scorpionate compounds mediate hydrocarbon oxidation with organic peroxides. Allylic oxidation of cyclohexene occurs mainly on the reaction with tert-butyl hydroperoxide (TBHP), although the catalytic efficiency of the scorpionate ligand complexes is lower than that of Co(OAc)2 and Co(acac)2. On cyclohexane oxidation with meta-chloroperbenzoic acid (mCPBA), both ToM and Tp? complexes function as catalysts for hydroxylation. The higher electron-donating ToM complexes show faster initial reaction rates compared to the corresponding Tp? complexes.
- Nishiura, Toshiki,Uramoto, Takahiro,Takiyama, Yuichiro,Nakazawa, Jun,Hikichi, Shiro
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- Enhanced shape selective catalysis of mixed cyclic ketones in aerobic Baeyer-Villiger oxidation with magnetic Cu-Fe3O4 supported mesoporous silica microspheres
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Various strategies have been developed to improve the conversion for the Baeyer-Villiger oxidation. However, the catalytic effects of the Baeyer-Villiger oxidation for the mixed ketones are rarely reported, though it is also important for the natural and industrial separation processes. In this report, magnetite Cu modified Fe3O4 supported mesoporous silica microspheres (Cu-Fe3O4@mSiO2) have been successfully synthesized by two step direct hydrothermal method (DHT). Over 99% of cyclohexanone conversion was obtained with mild air oxidation and benzaldehyde as sacrificing agent over Cu-Fe3O4@mSiO2. The catalytic system also shows higher conversion rates for small molecular ketones in the mixed ketone reactants, which was attributed to the enhanced mass transfer effect and Fe-Cu composite active sites in the magnetite mesoporous silica microspheres. The catalyst could be recycled for four times with similar catalytic performance, which shows enhanced shape selectivity in aerobic Baeyer-Villiger oxidations for mixed cyclic ketones.
- Zheng, Chunming,Chang, Shubin,Yang, Chuanwu,Lian, Dongying,Ma, Chao,Zhang, Chunrong,Fan, Xiangrui,Xu, Shichao,Sun, Xiaohong
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p. 2608 - 2616
(2018/04/23)
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- N-Hydroxyphthalimide (NHPI) Promoted Aerobic Baeyer-Villiger Oxidation in the Presence of Aldehydes
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Metal-free aerobic Baeyer-Villiger (BV) oxidation of ketones to lactones or esters in the presence of aldehydes promoted by N-hydroxyphthalimide (NHPI) has been developed. The reaction proceeded under mild conditions with excellent selectivity and high yields. Compared with the methods that use metal complexes as catalysts, this strategy not only showed good environmental advantages, but also increased aldehyde efficiency up to 84 %. Control experiments indicated that NHPI accelerated the oxidation of aldehydes to peroxy acids but did not improve the BV oxidation while peroxy acids were already generated. Peroxy acids generated from aldehydes in situ were the key intermediates, and the phthalimide-N-oxyl radical (PINO) contributed to high aldehyde efficiency by stabilizing the radical species, which are necessary for the chain propagation reactions. This study may offer some useful strategies for new transition metal-free catalytic aerobic oxidation reactions in which aldehydes act as sacrificial agents.
- Wang, Lingyao,Wang, Yongtao,Du, Renfeng,Dao, Rina,Yuan, Haoran,Liang, Cheng,Yao, Jia,Li, Haoran
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p. 4961 - 4966
(2018/10/02)
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- A tetranuclear diphenyltin(IV) complex and its catalytic activity in the aerobic Baeyer-Villiger oxidation of cyclohexanone
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The synthesis and crystal structure of the new tetranuclear diphenyltin(IV) compound [{SnPh2}{SnPh2(OCOMe)}(μ2-OMe)(μ3-O)]2 (1), generated from the reaction of [SnPh2Cl2] and NaOCOMe, are described. Single crystal X-ray diffraction revealed that 1 is a tetranuclear complex with four diphenyltin(IV) units which are inter-connected by μ3-oxido and μ2-methoxido bridges leading to a ladder-like Sn4O4 cluster. Structural comparison with related compounds found in crystallographic data base (CSD) attests that such tetranuclear systems are more abundant than related oxido bridged dimers or trimers. Complex 1 efficiently catalyzes the aerobic Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone, under mild conditions. With the sacrificial benzaldehyde method, quantitative conversion was observed in just 30 min with a remarkable selectivity.
- Hazra, Susanta,Martins, Nuno M.R.,Mahmudov, Kamran,Zubkov, Fedor I.,Guedes da Silva, M. Fátima C.,Pombeiro, Armando J.L.
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p. 193 - 200
(2018/01/10)
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- Pentafluoroperbenzoic acid as the efficient reagent for Baeyer–Villiger oxidation of cyclic ketones
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The Baeyer–Villiger oxidation of cyclic ketones with pentafluoroperbenzoic acid provides the corresponding lactones in 40–98% yields.
- Khusnutdinov, Ravil I.,Egorova, Tatyana M.,Aminov, Rishat I.,Dzhemilev, Usein M.
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p. 644 - 645
(2018/12/13)
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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supporting information
p. 6584 - 6592
(2018/10/05)
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- Facile aromatisation of Hantzsch 1,4-dihydropyridines by autoxidation in the presence of p-toluenesulfonic acid in acetic acid
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A simple protocol to achieve the aromatisation of Hantzsch dihydropyridines in high yield was established using p-toluenesulfonic acid in acetic acid and yields of 90% were obtained at room temperature. With regards to the Hantzsch 1,4-dihydropyridines derived from alkyl aldehydes bearing one or more á-hydrogens, dealkylation products were obtained through a proposed autoxidation mechanism.
- Zhang, Ding,Sha, Min
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p. 141 - 144
(2018/04/20)
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- Kinetics and enantioselectivity of the Baeyer-Villiger oxidation of cyclohexanones by chiral tetrapyridyl oxoiron(IV) complex
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The previously reported oxoiron(IV) complex, [FeIV(asN4Py)(O)]2+ with chiral pentadentate ligand, asN4Py (asN4Py = N,N?bis(2?pyridylmethyl)?1,2?di(2?pyridyl)ethylamine), is effective for the Baeyer-Villiger oxidation of cyclohexanone derivatives. The reaction is shown to be first order in both cyclohexanone and the oxoiron(IV) species. The second order rate constant is smaller by one order of magnitude than that obtained for the related achiral [FeIV(N4Py)(O)]2+ complex. Oxidation of 4-substituted cyclohexanone derivatives by the chiral oxoiron(IV) complex attains moderate enantioselectivities up to 45% enantiomeric excess (ee).
- Turcas, Ramona,Lakk-Bogáth, Dóra,Speier, Gábor,Kaizer, József
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p. 141 - 144
(2018/05/07)
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- Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional sustainable catalysts for base-free selective oxidative esterification of alcohols
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We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned. Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with long-chain alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability of the catalyst facilitated by its ease of separation for long-term performance and recycling studies showed that the catalyst was robust and remained active even after six recycling experiments. EPR measurements were performed to deduce the reaction mechanism in the presence of POBN (α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of CH2OH radicals and H radicals, wherein the solvent plays an active role in a nonconventional manner. A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
- Nandan, Devaki,Zoppellaro, Giorgio,Med?ík, Ivo,Aparicio, Claudia,Kumar, Pawan,Petr, Martin,Tomanec, Ond?ej,Gawande, Manoj B.,Varma, Rajender S.,Zbo?il, Radek
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p. 3542 - 3556
(2018/08/07)
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- Interrupted Baeyer–Villiger Rearrangement: Building A Stereoelectronic Trap for the Criegee Intermediate
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The instability of hydroxy peroxyesters, the elusive Criegee intermediates of the Baeyer–Villiger rearrangement, can be alleviated by selective deactivation of the stereoelectronic effects that promote the 1,2-alkyl shift. Stable cyclic Criegee intermediates constrained within a five-membered ring can be prepared by mild reduction of the respective hydroperoxy peroxyesters (β-hydroperoxy-β-peroxylactones) which were formed in high yields in reaction of β-ketoesters with BF3?Et2O/H2O2.
- Vil', Vera A.,dos Passos Gomes, Gabriel,Bityukov, Oleg V.,Lyssenko, Konstantin A.,Nikishin, Gennady I.,Alabugin, Igor V.,Terent'ev, Alexander O.
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p. 3372 - 3376
(2018/02/28)
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- Novel method for preparing epsilon-caprolactone
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The invention discloses a method for preparing epsilon-caprolactone. After cyclohexanone, co-oxidation agents, catalysts, radical initiators and solvents are mixed, reaction is performed in air atmosphere, the co-oxidation agents are methylbenzene compounds, the catalysts are at least one of nitrates or oxides of Co, Fe and Cu, the solvents are at least one selected from 1, 2-dichloroethane, ethyl acetate and acetonitrile, and the method for preparing the caprolactone further co-produces aromatic aldehyde and aromatic acid. The method for preparing the epsilon-caprolactone takes aromatic methyl compounds as the co-oxidation agents, benzaldehyde is replaced, production cost is remarkably reduced, industrial production of the epsilon-caprolactone prepared by an oxygen/air oxidation method is possible, and the aromatic aldehyde and the aromatic acid are further co-produced when the epsilon-caprolactone is prepared by the method, so that the method had higher values in industrial application.
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Paragraph 0061; 0062
(2017/08/29)
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- An alternative approach towards poly-ε-caprolactone through a chemoenzymatic synthesis: Combined hydrogenation, bio-oxidations and polymerization without the isolation of intermediates
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A novel synthetic route towards the polymer poly-ε-caprolactone based on a chemoenzymatic reaction sequence was developed. Initial hydrogenation of phenol to cyclohexanol gave a crude product, which was directly used without work-up for a subsequent biocatalytic double oxidation towards ε-caprolactone by means of an alcohol dehydrogenase and a monooxygenase. In order to overcome product inhibition effects, an in situ-product removal strategy via extraction of ε-caprolactone from an aqueous reaction medium with an organic solvent in the presence of a permeable polydimethylsiloxane membrane was applied. Furthermore, this in situ-product removal was combined with lipase-catalyzed polymerization in the organic phase at 25 °C. The obtained crude product contained a polymer fraction with a degree of polymerization comparable to commercial poly-ε-caprolactone.
- Wedde, Severin,Rommelmann, Philipp,Scherkus, Christian,Schmidt, Sandy,Bornscheuer, Uwe T.,Liese, Andreas,Gr?ger, Harald
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supporting information
p. 1286 - 1290
(2017/08/14)
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- Novel nickel(II) complexes of sterically modified linear N4 ligands: Effect of ligand stereoelectronic factors and solvent of coordination on nickel(II) spin-state and catalytic alkane hydroxylation
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A series of Ni(II) complexes of the types [Ni(L)(CH3CN)2](BPh4)21-3, 5 and [Ni(L4)](BPh4)24, where L = N,N′-bis(2-pyrid-2-ylmethyl)-1,4-diazepane (L1), N-(6-methylpyrid-2-ylmethyl)-N′-(pyrid-2-ylmethyl)-1,4-diazepane (L2), N,N′-bis(6-methyl-2-pyridylmethyl)-1,4-diazepane (L3), N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethylenediamine (L5) and L4 = N,N′-bis((1-methyl-1H-imidazole-2-yl)methyl)-1,4-diazepane, have been isolated and characterized. The complex cations of 1 and 4 possess, respectively, distorted octahedral and low-spin square planar coordination geometries in which nickel(II) is meridionally coordinated to all four nitrogen atoms of L1 and L4. DFT studies reveal that L5 with the ethylenediamine backbone coordinates in the cis-β mode in [Ni(L5)(CH3CN)2]2+5, but in the cis-α mode in [Ni(L5)(H2O)2]2+. Also, they illustrate the role of ligand donor atom type, diazacyclo backbone and steric hindrance to coordination of pyridyl nitrogen in conferring novel coordination geometries on Ni(II). All these complexes catalyse the oxidation of cyclohexane in the presence of m-CPBA as the oxidant up to 600 turnover numbers (TON) with relatively good alcohol selectivity (A/K, 5.6-7.2). Adamantane is oxidized to 1-adamantanol, 2-adamantanol and 2-adamantanone with high bond selectivity (3°/2°, 8.7-11.7). The incorporation of methyl substituent(s) on one (2) or both (3) of the pyridyl rings and the replacement of both the pyridylmethyl arms in 1 by imidazolylmethyl arms to give 4 decrease the catalytic efficiency. Interestingly, 5 with the cis-β mode of coordination provides two labile cis coordination sites for oxidant binding, leading to higher total TON and product/bond selectivity.
- Sankaralingam, Muniyandi,Vadivelu, Prabha,Palaniandavar, Mallayan
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p. 7181 - 7193
(2017/07/10)
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- Alkane oxidation reactivity of homogeneous and heterogeneous metal complex catalysts with mesoporous silica-immobilized (2-pyridylmethyl)amine type ligands
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Attachment of N,N-bis(2-pyridylmethyl)amine (L1) and N-(2-pyridylmethyl)glycine (L2) ligands on the azide-functionalized SBA-15 type mesoporous silica support and subsequent insertion of metal salts into the ligand-immobilized supports yielded heterogeneous metal complex catalysts, M(A)/SBA*-Ln-x, where M, A, *, n, and x indicate the metal ion (MnII, FeII, CoII, NiII, CuII), counter anion (Cl, OAc, OTf), trimethylsilyl end-capped silica, the numbering of the ligands, and the initial content of the azide tether group (tether/Si mol%) respectively. The cyclohexane oxidation activity of these immobilized catalysts and corresponding homogeneous complexes have been evaluated with the use of m-chloroperbenzoic acid as an oxidant. The activity of the immobilized catalysts is influenced by the ligand density on the support. Both the site-isolated immobilized catalysts and the related homogeneous catalysts of ligand L1 show similar trends of their final TONs on the type of metal ions (Co ≈ Ni > Fe > Mn > Cu). These results suggest that all of the metal complex sites are successfully immobilized without structural changes under the site-isolated condition. The reactivity trends of the complexes with the L2 ligand and their dependence on the ligand density were complicated. The observed results may be explained by the formation of cluster complexes via bridging carboxylate moieties of the ligand.
- Nakazawa, Jun,Doi, Yuma,Hikichi, Shiro
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- Process Development through Solvent Engineering in the Biocatalytic Synthesis of the Heterocyclic Bulk Chemical ε-Caprolactone
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For an alternative synthetic approach toward the heterocyclic industrial chemical ε-caprolactone, which is based on a biocatalytic oxidation of readily available cyclohexanol with air in aqueous media (using an alcohol dehydrogenase and a Baeyer–Villiger monooxygenase as enzyme components), a solvent engineering has been carried out identifying isooctane as a suitable co-solvent. Biotransformations in an aqueous-isooctane biphasic solvent system were found to proceed faster at both investigated substrate concentrations of 40 and 80 mm, respectively, compared with the analogous enzymatic reactions in pure aqueous medium. In addition, in all cases quantitative conversions were observed after a reaction time of 23 h when using isolated enzymes. The achievements indicate a high compatibility of isooctane [10%(v/v)] with the enzymes as well as the potential for an in situ removal of the organic reaction components, thus decreasing inhibition and/or destabilization effects of these organic components on the enzymes used. In contrast, so far, the use of recombinant whole-cells gave less satisfactory results, which might be due to limitations of the permeation of, for example, the substrate through the cell membrane.
- Reimer, Anna,Wedde, Severin,Staudt, Svenja,Schmidt, Sandy,H?ffer, Diana,Hummel, Werner,Kragl, Udo,Bornscheuer, Uwe T.,Gr?ger, Harald
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p. 391 - 396
(2017/02/05)
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