- Selective oxidation of 1,2-diols by electrochemical method using organotin compound and bromide ion as mediators
-
A new electrochemical method for a selective oxidation of 1,2-diols to keto alcohols was explored. The method used dibutyltin oxide and bromide ion as mediators, and the oxidation was found to proceed effectively at 0°C under neutral conditions. Under these reaction conditions, 1,2-cyclohexanediol was selectively oxidized even in the presence of primary and secondary alcohols.
- Maki, Toshihide,Fukae, Kazuhiro,Harasawa, Hitomi,Ohishi, Takahiro,Matsumura, Yoshihiro,Onomura, Osamu
-
-
Read Online
- Mechanistic aspects of the bismuth-catalysed oxidation of epoxides to α-diketones
-
The mechanism of the direct oxidation of 1,2-disubstituted epoxides to α-diketones catalysed by BiIII derivatives was examined. The oxidation was carried out in DMSO under dioxygen. Experimental evidence for the various steps of the reaction was obtained from spectroscopic data, isolation of intermediate species, reactions with Bi0, reaction under dinitrogen rather than under dioxygen, measurement of the oxygen consumption, cyclic voltammetry, and oxidations performed in the presence of methyl phenyl sulfoxide. The direct epoxide-to-diketone oxidation involves two main reaction steps: a first DMSO-mediated oxidative ring-opening of the oxirane ring, and a second Bi-catalysed oxidation to the α-diketone by dioxygen. A catalytic cycle is proposed combining the different results. A new alternative preparation of Bi(OTf)3 by oxidative dissolution of Bi0 is also described. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Antoniotti, Sylvain,Dunach, Elisabet
-
-
Read Online
- A zinc-dependent alcohol dehydrogenase (ADH) from Thauera aromatica, reducing cyclic α- And β-diketones
-
Zinc-dependent alcohol dehydrogenases (ADHs) are valuable biocatalysts for the synthesis of chiral hydroxy compounds such as α-hydroxy ketones and diols, both valuable precursors for the synthesis of various pharmaceuticals. However, while highly active on aliphatic or phenyl-substituted diketones, most well characterized ADHs show no significant activity on cyclic α- and β-diketones. Therefore, this study aimed at the detection of a novel ADH capable to reduce these special targets. It involved a rational screening of biochemical pathways for enzymes with structurally related natural substrates. The so detected 6-hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase (ThaADH) from Thauera aromatica was cloned, expressed in Escherichia coli and purified by affinity chromatography. The characterization revealed a substrate specificity with highest activities on cyclic α- and β-diketones including 1,2-cyclohexanedione and 1,3-cyclopentanedione. Structural reasons for this extraordinary substrate spectrum were investigated with a homology model created via Swiss Model server. Although the quality of the model may be improved, it suggests that a bulky aromatic residue, that plays a crucial role in the definition of the substrate binding pockets of most ADHs, is replaced by a glycine residue in ThaADH. We propose that this structural difference leads to the formation of one large binding pocket instead of two smaller ones and consequently to a preference for cyclic diketones over linear bulky substrates. Thus, we have achieved both provision of a novel biocatalyst with high potential in chiral synthesis, and a possible explanation for the measured differences to known ADHs. The described structural motif might be used for identification of further enzymes with a related substrate scope.
- Loderer, Christoph,Morgenstern, Frances,Ansorge-Schumacher, Marion
-
-
Read Online
- Citric acid mediated catalytic osmylation/oxidative cleavage of electron deficient olefins: A vinyl sulfone study
-
The first broad catalytic dihydroxylation of enantiopure cyclic vinyl sulfones followed by oxidative cleavage of the resulting acyloin provides linear termini-differentiated polyketide fragments. This mild vinyl sulfone cleavage provides an effective alternative to the current ozonolysis protocol.
- Bobinski, Thomas P.,Fuchs, Philip L.
-
-
Read Online
- Aerobic photooxidation in water by polyoxotungstates: The case of uracil
-
Uracil photooxygenation occurs in acidic water (pH = 1) at 25°C, under oxygen (1 atm), irradiating with γ > 300 nm in the presence of selected polyoxometalates (POM). A marked diversity of photocatalytic behavior is registered for different POMs in terms of oxidation rate and selectivity. H 3PW12O40 (PW12) appears to be the most reactive photocatalyst, by far superior to isostructural complexes, leading to a product distribution typical of OH. dominated oxidations, while Na4W10O32 (W10) and Na 12[WZn3(H2O)2(ZnW9O 34)2] (Zn5W19) exhibit a preferential reactivity towards uracil glycol. Kinetic studies and radical scavenger probes, performed on target intermediates and model diols, highlight a substantial difference in the mechanism of photocatalysis by the three complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Bonchio, Marcella,Carraro, Mauro,Conte, Valeria,Scorrano, Gianfranco
-
-
Read Online
- One-pot production of phenazine from lignin-derived catechol
-
Upgrading lignin-derived monomeric products is crucial in bio-refineries to effectively utilize lignin. Herein, we report a simple strategy to convert catechol to phenazine, a useful N-heterocycle three-aromatic-ring compound, whose current synthetic procedure is complex via a petroleum-derived feedstock. The reaction uses catechol as the sole carbon source and aqueous ammonia as reaction media and a nitrogen source. Without additional solvents, phenazine was obtained in 67% yield in the form of high purity crystals (>97%) over a Pd/C catalyst after a one-pot-two-stage reaction. When cyclohexane was used as a co-solvent in the first step, a higher yield (81%) and purity (>99%) were achieved. Mechanistic investigations involving control experiments and an isotope labeling study reveal that hydrogenation, amination, coupling and dehydrogenation reactions are the key steps leading to phenazine formation. The conversion of other lignin-derived catechols highlights that the protocol is extendable to produce substituted phenazines.
- He, Zhimin,Qi, Wei,Ren, Tianyu,Yan, Ning
-
supporting information
p. 1224 - 1230
(2022/02/17)
-
- Selective Isomerization via Transient Thermodynamic Control: Dynamic Epimerization of trans to cis Diols
-
Traditional approaches to stereoselective synthesis require high levels of enantio- and diastereocontrol in every step that forms a new stereocenter. Here, we report an alternative approach, in which the stereochemistry of organic substrates is selectivel
- Macmillan, David W. C.,Oswood, Christian J.
-
supporting information
p. 93 - 98
(2022/01/03)
-
- Copper-Mediated Dichotomic Borylation of Alkyne Carbonates: Stereoselective Access to (E)-1,2-Diborylated 1,3-Dienes versus Traceless Monoborylation Affording α-Hydroxyallenes
-
A mild copper-mediated protocol has been developed for borylation of alkynyl cyclic carbonates. Depending on the nature of the borylating reaction partner, either stereoselective diborylation of the propargylic surrogate takes place, providing convenient access to (E)-1,2-borylated 1,3-dienes, or traceless monoborylation occurs, which leads to α-hydroxyallenes as the principal product. The dichotomy in this borylation protocol has been scrutinized by several control experiments, illustrating that a relatively small change in the diboron(4) reagent allows for competitive alcohol-assisted protodemetalation to forge an α-hydroxyallene product under ambient conditions.
- Guo, Kun,Kleij, Arjan W.
-
p. 4901 - 4906
(2021/01/21)
-
- Catalytic Highly Regioselective C-H Oxygenation Using Water as the Oxygen Source: Preparation of 17O/18O-Isotope-Labeled Compounds
-
We found that the oxygen atom of water is activated to iodosylbenzene derivatives via reversible hydrolysis of PhI(OOCR)2 and can be used to the oxygen source for ruthenium(bpga)-catalyzed site-selective C-H oxygenation. Ru(bpga)/PhI(OOCR)2/H2O system, sterically less bulky methinic and methylenic C-H bonds in various compounds can be converted to desired oxygen functional groups in a site-selective manner. Using this method, oxygen-isotope labeled compounds such as d-[3-17O/18O]-mannose can be prepared in a multigram scale.
- Doiuchi, Daiki,Uchida, Tatsuya
-
supporting information
p. 7301 - 7305
(2021/10/01)
-
- Activation of H2O2over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates
-
Zr-monosubstituted Lindqvist-type polyoxometalates (Zr-POMs), (Bu4N)2[W5O18Zr(H2O)3] (1) and (Bu4N)6[{W5O18Zr(μ-OH)}2] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C?C bonds in unfunctionalized alkenes and α,β-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an 17O-enriched dimer, (Bu4N)6[{W5O18Zr(μ-OCH3)}2] (2′), and H2O2 was also analyzed by 17O NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(μ-?2:?2-O2){ZrW5O18}2]6- as well as monomeric Zr-hydroperoxo [W5O18Zr(?2-OOH)]3- and Zr-peroxo [HW5O18Zr(?2-O2)]3- species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C?C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding α-oxygen transfer to the substrate as the rate-determining step. The calculations also showed that protonation of Zr-POM significantly reduces the free-energy barrier of the key oxygen-transfer step because of the greater electrophilicity of the catalyst and that dimeric species hampers the approach of alkene substrates due to steric repulsions reducing its reactivity. The improved performance of the Zr(IV) catalyst relative to Ti(IV) and Nb(V) catalysts is respectively due to a flexible coordination environment and a low tendency to form energy deep-well and low-reactive Zr-peroxo intermediates.
- Abramov, Pavel A.,Carbó, Jorge J.,Chesalov, Yuriy A.,Eltsov, Ilia V.,Errington, R. John,Evtushok, Vasilii Yu.,Glazneva, Tatyana S.,Ivanchikova, Irina D.,Kholdeeva, Oxana A.,Maksimchuk, Nataliya V.,Maksimov, Gennadii M.,Poblet, Josep M.,Solé-Daura, Albert,Yanshole, Vadim V.,Zalomaeva, Olga V.
-
p. 10589 - 10603
(2021/09/02)
-
- Novel hypervalent iodine catalyzed synthesis of α-sulfonoxy ketones: Biological activity and molecular docking studies
-
The novel di((camphorsulfonyl)oxy)iodo]benzene (DCIB) was synthesized from [Bis(trifluoroacetoxy)iodo]benzene in the mild conditions. The α-sulfonoxylation of various ketones with novel hypervalent iodine was reported in excellent yield. α-Hydroxyketones
- Atmaca, Ufuk,Alp, Cemalettin,Akincioglu, Hulya,Karaman, Halide Sedef,Gül?in, ?lhami,?elik, Murat
-
-
- A Zr-Based Metal-Organic Framework with a DUT-52 Structure Containing a Trifluoroacetamido-Functionalized Linker for Aqueous Phase Fluorescence Sensing of the Cyanide Ion and Aerobic Oxidation of Cyclohexane
-
A zirconium (Zr) metal-organic framework having a DUT-52 (DUT stands for Dresden University of Technology) structure with face-centered cubic topology and bearing the rigid 1-(2,2,2-trifluoroacetamido) naphthalene-3,7-dicarboxylic acid (H2NDC-NHCOCF3) ligand was prepared, and its solid structure was characterized with the help of the X-ray powder diffraction (XRPD) technique. Other characterization methods like thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy were applied to verify the phase purity of the compound. In order to get the solvent-free compound (1′), 1 was stirred with methanol for overnight and subsequently heated at 100 °C overnight under vacuum. As-synthesized (1) and activated (1′) compounds are thermally stable up to 300 °C. The Brunsuer Emmett-Teller (BET) surface area of 1′ was found to be 1105 m2 g-1. Fluorescence titration experiments showed that 1′ exhibits highly selective and sensitive fluorescence turn-on behavior toward cyanide (CN-) anion. The interference experiments suggested that other anions did not interfere in the detection of CN-. Moreover, a very short response time (2 min) was shown by probe 1′ for CN- detection. The detection limit was found to be 0.23 μM. 1′ can also be effectively used for CN- detection in real water samples. The mechanism for the selective detection of CN- was investigated systematically. Furthermore, the aerobic oxidation of cyclohexane was performed with 1′ under mild reaction conditions, observing higher activity than the analogous DUT-52 solid under identical conditions. These experiments clearly indicate the benefits of hydrophobic cavities of 1′ in achieving higher conversion of cyclohexane and cyclohexanol/cyclohexanone selectivity. Catalyst stability was proved by two consecutive reuses and comparing the structural integrity of 1′ before and after reuses by the XRPD study.
- Gogoi, Chiranjib,Nagarjun, Nagarathinam,Roy, Shubasis,Mostakim,Volkmer, Dirk,Dhakshinamoorthy, Amarajothi,Biswas, Shyam
-
supporting information
p. 4539 - 4550
(2021/04/06)
-
- Catalytic Performance of Zr-Based Metal–Organic Frameworks Zr-abtc and MIP-200 in Selective Oxidations with H2O2
-
The catalytic performance of Zr-abtc and MIP-200 metal–organic frameworks consisting of 8-connected Zr6 clusters and tetratopic linkers was investigated in H2O2-based selective oxidations and compared with that of 12-coordinated UiO-66 and UiO-67. Zr-abtc demonstrated advantages in both substrate conversion and product selectivity for epoxidation of electron-deficient C=C bonds in α,β-unsaturated ketones. The significant predominance of 1,2-epoxide in carvone epoxidation, coupled with high sulfone selectivity in thioether oxidation, points to a nucleophilic oxidation mechanism over Zr-abtc. The superior catalytic performance in the epoxidation of unsaturated ketones correlates with a larger amount of weak basic sites in Zr-abtc. Electrophilic activation of H2O2 can also be realized, as evidenced by the high activity of Zr-abtc in epoxidation of the electron-rich C=C bond in caryophyllene. XRD and FTIR studies confirmed the retention of the Zr-abtc structure after the catalysis. The low activity of MIP-200 in H2O2-based oxidations is most likely related to its specific hydrophilicity, which disfavors adsorption of organic substrates and H2O2.
- Maksimchuk, Nataliya V.,Ivanchikova, Irina D.,Cho, Kyung Ho,Zalomaeva, Olga V.,Evtushok, Vasiliy Yu.,Larionov, Kirill P.,Glazneva, Tatiana S.,Chang, Jong-San,Kholdeeva, Oxana A.
-
supporting information
p. 6985 - 6992
(2021/03/17)
-
- Enantioselective Cascade Biocatalysis for Deracemization of Racemic β-Amino Alcohols to Enantiopure (S)-β-Amino Alcohols by Employing Cyclohexylamine Oxidase and ω-Transaminase
-
Optically active β-amino alcohols are very useful chiral intermediates frequently used in the preparation of pharmaceutically active substances. Here, a novel cyclohexylamine oxidase (ArCHAO) was identified from the genome sequence of Arthrobacter sp. TYUT010-15 with the R-stereoselective deamination activity of β-amino alcohol. ArCHAO was cloned and successfully expressed in E. coli BL21, purified and characterized. Substrate-specific analysis revealed that ArCHAO has high activity (4.15 to 6.34 U mg?1 protein) and excellent enantioselectivity toward the tested β-amino alcohols. By using purified ArCHAO, a wide range of racemic β-amino alcohols were resolved, (S)-β-amino alcohols were obtained in >99 % ee. Deracemization of racemic β-amino alcohols was conducted by ArCHAO-catalyzed enantioselective deamination and transaminase-catalyzed enantioselective amination to afford (S)-β-amino alcohols in excellent conversion (78–94 %) and enantiomeric excess (>99 %). Preparative-scale deracemization was carried out with 50 mM (6.859 g L?1) racemic 2-amino-2-phenylethanol, (S)-2-amino-2-phenylethanol was obtained in 75 % isolated yield and >99 % ee.
- Zhang, Jian-Dong,Chang, Ya-Wen,Dong, Rui,Yang, Xiao-Xiao,Gao, Li-Li,Li, Jing,Huang, Shuang-Ping,Guo, Xing-Mei,Zhang, Chao-Feng,Chang, Hong-Hong
-
p. 124 - 128
(2020/09/21)
-
- Structural elucidation, DFT calculations and catalytic activity of dioxomolybdenum(VI) complexes with N–N donor ligand: Role of halogen atom coordinated to the molybdenum centre
-
Two new isostructural mononuclear dioxomolybdenum(VI) complexes of the formula MoO2X2L [where, X = Cl (1), Br (2)] have been synthesized with a N–N donor 2-(3-methyl-5-phenyl pyrazol-1-yl) benzthiazole ligand (L). The reaction is carried out in open air and the MoVO3+ centre in the precursor molecule, MoOX3L undergoes spontaneous aerial oxidation, leading to the formation of molybdenum(VI) complexes 1 and 2. The complexes are characterized by a wide range of spectroscopic techniques (IR, UV–Vis and 1H NMR) and elemental analyses. Crystal structures of the ligand and complexes 1 and 2 have been determined by single crystal X-ray diffraction which reveal a distorted octahedral geometry around the molybdenum(VI) centre in both the complexes. The ligand and the complexes build up fascinating supramolecular assembly via several non-covalent interactions including hydrogen bonding, C–H···π and π···π interactions. Further, a detailed study of Hirshfeld surface analysis and fingerprint plots of complexes 1 and 2 are presented for understanding the intermolecular interactions involved in building self-assembled frameworks. Supportive DFT and TD-DFT calculations have also been carried out. Electrochemical properties of the complexes have been examined by cyclic voltammetry. Catalytic performance of the synthesized complexes has been evaluated for the oxidation of different olefins in the presence of hydrogen peroxide.
- Roy, Malini,Biswal, Debanjana,Pramanik, Nikhil Ranjan,Drew, Michael G.B.,Paul, Suvendu,Kachhap, Payal,Haldar, Chanchal,Chakrabarti, Syamal
-
-
- POLITAG-Pd(0) catalyzed continuous flow hydrogenation of lignin-derived phenolic compounds using sodium formate as a safe H-source
-
Phenols are aromatic biobased compounds and as they are accessible from lignin depolymerization, they can be a useful platform chemicals to produce value-added products. Herein we report our recent investigations on the definition of an approach to the efficient continuous flow selective hydrogenation of phenols in water. Our protocol is based on the use of sodium formate as a clean and safe hydrogen source in combination with our newly defined heterogeneous POLITAG-Pd(0) catalytic system. POLITAG is a polymeric heterogeneous support decorated with pincer-type ionic ligands proven to be highly efficient for the stabilization of Pd(0) nanoparticles. The results obtained are remarkable in comparison with other protocols that employ sodium formate as H-source. Indeed, our investigation has been extended to a variety of differently substituted phenolic compounds that have been hydrogenated with excellent to good selectivity in continuous flow conditions. Durability of the catalyst has been also tested with a representative continuous processing of over 100 mmol that showed no loss in efficiency and minimal metal leaching.
- Campana, Filippo,Ferlin, Francesco,Silvetti, Matteo,Trombettoni, Valeria,Vaccaro, Luigi,Valentini, Federica
-
-
- SULFONYLUREA DERIVATIVES AND USES THEREOF
-
The present disclosure relates to compounds of Formula (I) and to their prodrugs, pharmaceutically acceptable salts, pharmaceutical compositions, methods of use, and methods for their preparation. The compounds disclosed herein are useful for inhibiting the maturation of cytokines of the IL-1 family by inhibiting inflammasomes and may be used in the treatment of disorders in which inflammasome activity is implicated, such as inflammatory, autoinflammatory and autoimmune diseases and cancers.
- -
-
Paragraph 01425-01426
(2020/12/30)
-
- SYNTHESIS AND APPLICATION OF CHIRAL SUBSTITUTED POLYVINYLPYRROLIDINONES
-
Chiral polyvinylpyrrolidinone (CSPVP), complexes of CSPVP with a core species, such as a metallic nanocluster catalyst, and enantioselective oxidation reactions utilizing such complexes are disclosed. The CSPVP complexes can be used in asymmetric oxidation of diols, enantioselective oxidation of alkenes, and carbon-carbon bond forming reactions, for example. The CSPVP can also be complexed with biomolecules such as proteins, DNA, and RNA, and used as nanocarriers for siRNA or dsRNA delivery.
- -
-
Paragraph 0046; 0047; 0049
(2020/11/24)
-
- Site-Selective and Product Chemoselective Aliphatic C-H Bond Hydroxylation of Polyhydroxylated Substrates
-
Site-selective and product chemoselective aliphatic C-H bond oxidation of 1,2-diols and of polyhydroxylated substrates using iron and manganese catalysts and hydrogen peroxide as terminal oxidant is described. The reaction capitalizes on the use of fluorinated alcohol solvents such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), which exert a strong polarity reversal in the hydroxyl moieties of 1,2-diols via hydrogen bonding, in turn translating into a strong deactivation of proximal C-H bonds against a HAT initiated oxidation by the putative high-valent and electrophilic metal-oxo species. As a result, site-selective and product chemoselective oxidation of complex polyfunctional molecules such as steroids, sugars, and pharmaceuticals is described, where exclusive or predominant C-H bond hydroxylation at a remote and nonactivated site takes place. The current report discloses HAT initiated hydroxylations in fluorinated alcohol solvents as methods displaying orthogonal chemoselectivity to contemporary alcohol oxidations providing a useful tool for synthetic planning in densely functionalized molecules.
- Bietti, Massimo,Borrell, Margarida,Costas, Miquel,Gil-Caballero, Sergio
-
p. 4702 - 4709
(2020/05/19)
-
- H2O2-based selective oxidations by divanadium-substituted polyoxotungstate supported on nitrogen-doped carbon nanomaterials
-
In this work, we present a new methodology for the preparation of highly active, selective, leaching-tolerant and recyclable catalysts on the basis of polyoxometalates (POM) and nitrogen-doped carbon nanomaterials. A divanadium-substituted γ-Keggin phosphotungstate [γ-PW10O38V2(μ-O)(μ?OH)]4? (PV2), was immobilized on two types of supports – N-doped carbon nanofibers (N-CNFs) having herring-bone packing of graphite layers and bamboo-like N-doped carbon nanotubes (N-CNTs). Two series of catalysts have been prepared and characterized by elemental analysis, N2 adsorption, TEM, XPS and FTIR techniques. Their catalytic performance was assessed in the liquid-phase selective oxidation of two representative organic substrates, 2,3,6-trimethylphenol and cyclohexene, with aqueous H2O2 as the green oxidant. The presence of nitrogen in the supports ensures strong binding and quasi-molecular dispersion of POM on the carbon surface, which is crucial for the catalytic performance and catalyst stability. The catalysts reveal truly heterogeneous nature of the catalysis and can be easily recovered and reused without loss of the catalytic performance. The morphology of the support has a significant impact on the catalytic performance: the supported PV2 catalysts prepared using N-CNTs are more active and, in general, more selective than the catalysts prepared with N-CNFs.
- Evtushok, Vasiliy Yu.,Podyacheva, Olga Yu.,Suboch, Arina N.,Maksimchuk, Nataliya V.,Stonkus, Olga A.,Kibis, Lidiya S.,Kholdeeva, Oxana A.
-
p. 196 - 203
(2019/04/03)
-
- Demethoxylation of hydrogenated derivatives of guaiacol without external hydrogen over platinum catalyst
-
Selective deoxygenation of 2-methoxycyclohexanone, one of the hydrogenated by-products in guaiacol hydrodeoxygenation, to phenol, cyclohexanone and cyclohexanol was investigated over carbon supported noble metal catalysts without external H2. Pt/C exhibited the best performance and the yield of target products reached 48% in water solvent at 493 K. This system can be applied to demethoxylation of 2-methoxycyclohexanol (49% yield). Demethoxylation of guaiacol is also possible under 0.1 MPa of H2 (46% yield). The yield of the target demethoxylation products was strongly dependent on the catalyst amount; too much catalyst decreased the yield due to the over-reaction, while the reaction stopped before total conversion of intermediates when the catalyst amount was too small. Fresh Pt/C catalyst has activity in hydrodeoxygenation of the target products and the reusability test showed deactivation of Pt/C during reaction, suggesting that deactivation at appropriate reaction progress controlled by catalyst amount is a key to good yield of the target products. In contrast to other noble metal catalysts, Pt/C has activity in both dehydrogenation of cyclohexane ring and hydrogenolysis of C–O bond, both of which contributed to the conversion of 2-methoxycyclohexanone to target demethoxylation products, according to the reactions of cyclohexanone and cyclohexanol as model substrates.
- Miyagawa, Akari,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
-
-
- Efficient Oxidation of Benzylic and Aliphatic Alcohols Using a Bioinspired Cross-Bridged Cyclam Manganese Complex with H2O2
-
The cross-bridged cyclam manganese complex Mn(Me2EBC)Cl2 efficiently catalyzes the oxidation of benzylic and aliphatic alcohols at pH 3 in a mixture of acetonitrile and water at room temperature. The environmentally benign and high oxygen content oxidant H2O2 was adopted. Conversions of the alcohols to the corresponding carbonyl compounds reached 98 % with good to excellent selectivity. In addition, several lignin model compounds were also catalytically oxidized under these conditions, with excellent conversion (up to 96 %) and selectivity (up to 99 %).
- Zhang, Zhan,Khrouz, Lhoussain,Yin, Guochuan,Andrioletti, Bruno
-
supporting information
p. 323 - 327
(2018/11/27)
-
- Ultrafast synthesis of nanosized Ti-Beta as an efficient oxidation catalyst: Via a structural reconstruction method
-
As a representative selective oxidation titanosilicate catalyst, a Ti-Beta zeolite is less used in comparison with TS-1, Ti-MWW and Ti-MOR, mostly due to its high hydrophilicity originating from a BEA? intergrowth framework. A novel recrystallization method was proposed in the present study to prepare highly hydrophobic Ti-Beta with nanosized crystals (90 nm), high Ti content (Si/Ti = 20) and intercrystal mesoporosity. The fluoride-assisted recrystallization was realized quickly by dissolving extensively a dealuminated Beta zeolite in a mixture of a tetraethylammonium aqueous solution and Ti precursor, producing highly crystalline Ti-Beta in an extremely short time of 1 h. The obtained Ti-Beta zeolite exhibited superior catalytic activity in the liquid-phase epoxidation reactions of bulky alkenes like cyclohexene with hydrogen peroxide or tert-butyl hydroperoxide as an oxidant, compared to those Ti-Beta catalysts prepared by conventional hydrothermal or secondary synthesis routes.
- Wang, Bowen,Xu, Hao,Zhu, Zhiguo,Guan, Yejun,Wu, Peng
-
p. 1857 - 1866
(2019/04/29)
-
- Polymer-anchored mononuclear and binuclear CuII Schiff-base complexes: Impact of heterogenization on liquid phase catalytic oxidation of a series of alkenes
-
Liquid phase catalytic oxidation of a number of alkenes, for example, cyclohexene, cis-cyclooctene, styrene, 1-methyl cyclohexene and 1-hexene, was performed using polymer-anchored copper (II) complexes PS-[Cu (sal-sch)Cl] (5), PS-[Cu (sal-tch)Cl] (6), PS-[CH2{Cu (sal-sch)Cl}2] (7) and PS-[CH2{Cu (sal-tch)Cl}2] (8). Neat complexes [Cu (sal-sch)Cl] (1), [Cu (sal-tch)Cl] (2), [CH2{Cu (sal-sch)Cl}2] (3) and [CH2{Cu (sal-tch)Cl}2] (4) were isolated by reacting CuCl2·2H2O with [Hsal-sch] (I), [Hsal-tch] (II), [H2bissal-sch] (III) and [H2bissal-tch] (IV), respectively, in refluxing methanol. Complexes 1–4 have been covalently anchored in Merrifield resin through the amine nitrogen of the semicarbazide or thiosemicarbazide moiety. A number of analytical, spectroscopic and thermal techniques, such as CHNS analysis, Fourier transform-infrared, UV–Vis, PMR, 13C-NMR, electron paramagnetic resonance, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetric analysis, atomic force microscopy, atomic absorption spectroscopy, and electrospray ionization-mass spectrometry, were used to analyze and establish the molecular structure of the ligands (I)–(IV) and complexes (1)–(8) in solid state as well as in solution state. Grafted complexes 5–8 were employed as active catalysts for the oxidation of a series of alkenes in the presence of hydrogen peroxide. Copper hydroperoxo species ([CuIII (sal-sch)-O-O-H]), which is believed to be the active intermediate, generated during the catalytic oxidation of alkenes, are identified. It was found that supported catalysts are very economical, green and efficient in contrast to their neat complexes as well as most of the recently reported heterogeneous catalysts.
- Maurya, Abhishek,Kesharwani, Neha,Kachhap, Payal,Mishra, Vivek Kumar,Chaudhary, Nikita,Haldar, Chanchal
-
-
- Oxy-functionalization of olefins with neat and heterogenized binuclear V(IV)O and Fe(II)complexes: Effect of steric hindrance on product selectivity and output in homogeneous and heterogeneous phase
-
Neat {[VO(sal2bz)]2; [Fe(sal2bz)(H2O)2]2·2H2O} and zeolite-Y immobilized {[VO(sal2bz)]2-Y; [Fe(sal2bz)(H2O)2]2-Y} binuclear complexes have been prepared and characterized by spectroscopic techniques (IR, UV–vis), elemental analyses (CHN, ICP-OES), thermal study (TGA), scanning electron micrograph (SEM), adsorption study (BET)and X-ray diffraction (XRD)patterns. Neat (homogeneous)and immobilized (heterogeneous)complexes were employed as catalysts in the oxidation of olefins, namely, cyclohexene, limonene and α-pinene in the presence of 30% hydrogen peroxide. 100% conversion of cyclohexene and α-pinene was obtained while limonene was oxidized up to 90%. Homogeneous catalysts showed highly selective result as neat [VO(sal2bz)]2 complex has provided 87% cyclohexane-1,2-diol and neat [Fe(sal2bz)(H2O)2]2·2H2O complex has provided 79% verbenone in oxidation of cyclohexene and α-pinene, respectively. We have observed that due to steric hindrance, formation of olefinic oxidation products increases on moving from α-pinene to limonene and limonene to cyclohexene. Additionally. recovered heterogeneous catalysts showed intact results up to two consecutive runs. Probable catalytic mechanism has been proposed for oxidation of cyclohexene.
- Parmar, Digvijaysinh K.,Butani, Pinal M.,Thumar, Niraj J.,Jasani, Pinal M.,Padaliya, Ravi V.,Sandhiya, Paba R.,Nakum, Haresh D.,Khan, Md. Nasim,Makwana, Dipak
-
-
- Hydrogenation of Phenol to Cyclohexanone over Bifunctional Pd/C-Heteropoly Acid Catalyst in the Liquid Phase
-
Abstract: Cyclohexanone is an important intermediate in the manufacture of polyamides in chemical industry, but direct selective hydrogenation of phenol to cyclohexanone under mild conditions is a challenge. Hydrogenation of phenol to cyclohexanone has been investigated in the presence of the composite catalytic system of Pd/C-heteropoly acid. 100% conversion of phenol and 93.6% selectivity of cyclohexanone were achieved within 3?h under 80?°C and 1.0?MPa hydrogen pressure. It has been found that a synergetic effect of Pd/C and heteropoly acid enhanced the catalytic performance of the composite catalytic system which suppressed the hydrogenation of cyclohexanone to cyclohexanol. Graphic Abstract: [Figure not available: see fulltext.].
- Liu, Shiwei,Han, Jing,Wu, Qiong,Bian, Bing,Li, Lu,Yu, Shitao,Song, Jie,Zhang, Cong,Ragauskas, Arthur J.
-
p. 2383 - 2389
(2019/06/19)
-
- One-Pot Enzymatic Synthesis of Cyclic Vicinal Diols from Aliphatic Dialdehydes via Intramolecular C?C Bond Formation and Carbonyl Reduction Using Pyruvate Decarboxylases and Alcohol Dehydrogenases
-
An enzymatic cascade reaction was developed for one-pot enantioselective conversion of aliphatic dialdehydes to chiral vicinal diols using pyruvate decarboxylases (PDCs) and alcohol dehydrogenases (ADHs). The PDCs showed promiscuity in catalysing the cyclization of aliphatic dialdehydes through intramolecular stereoselective carbon-carbon bond formation. Consequently, 1,2-cyclopentanediols in three different stereoisomeric forms and 1,2-cyclohexanediols in two different stereoisomeric forms could be prepared with high conversion and stereoisomeric ratio from the respective initial substrates, glutaraldehyde and adipaldehyde. These cascade reactions represent a promising approach to the biocatalytic synthesis of important chiral vicinal diols. (Figure presented.).
- Zhang, Yan,Yao, Peiyuan,Cui, Yunfeng,Wu, Qiaqing,Zhu, Dunming
-
p. 4191 - 4196
(2018/09/25)
-
- Relevance of Protons in Heterolytic Activation of H2O2 over Nb(V): Insights from Model Studies on Nb-Substituted Polyoxometalates
-
Nb-monosubstituted Lindqvist-type polyoxometalates (POM), (Bu4N)4[(NbW5O18)2O] (1) and (Bu4N)3[Nb(O)W5O18] (2), catalyze epoxidation of alkenes with hydrogen peroxide and mimic the catalytic performance of heterogeneous Nb-silicate catalysts. Dimer 1 is more active than monomer 2, but the catalytic activity of the latter increases in the presence of acid. Kinetic and spectroscopic studies suggest a mechanism that involves generation of monomer (Bu4N)2[Nb(OH)W5O18] (3), interaction of 3 with H2O2 leading to a protonated peroxo niobium species, (Bu4N)2[HNb(O2)W5O18] (4), followed by oxygen transfer to a C=C bond in alkene. The previously unknown peroxo complex 4 has been isolated and characterized by elemental analysis; UV-vis, FT-IR, Raman, 93Nb, 17O and 183W NMR spectroscopy; cyclic voltammetry; and potentiometric titration. The physicochemical techniques support a monomeric Lindqvist structure of 4 bearing one peroxo ligand attached to Nb(V) in a η2-coordination mode. While the unprotonated peroxo complex (Bu4N)3[Nb(O2)W5O18] (5) is inert toward alkenes under stoichiometric conditions, 4 readily reacts with cyclohexene to afford epoxide and 1,2-trans-cyclohexane diol, which proves the key role of protons for heterolytic activation of H2O2 over Nb(V). The IR, Raman, UV-vis, and 17O NMR spectroscopic studies along with DFT calculations showed that the activating proton in 4 is predominantly located at a Nb-O-W bridging oxygen. However, DFT calculations revealed that the protonated peroxo species "HNb(O2)" is present in equilibrium with a hydroperoxo species "Nb(η2-OOH)," which has a lower activation barrier for the oxygen transfer to cyclohexene and is, therefore, the main epoxidizing species. The calculations indicate that protonation is crucial to generating the active species and to increasing POM electrophilicity.
- Maksimchuk, Nataliya V.,Maksimov, Gennadii M.,Evtushok, Vasilii Yu.,Ivanchikova, Irina D.,Chesalov, Yuriy A.,Maksimovskaya, Raisa I.,Kholdeeva, Oxana A.,Solé-Daura, Albert,Poblet, Josep M.,Carbó, Jorge J.
-
p. 9722 - 9737
(2018/10/20)
-
- High-Cluster (Cu9) Cage Silsesquioxanes: Synthesis, Structure, and Catalytic Activity
-
Unusual high-cluster (Cu9) cage phenylsilsesquioxanes were obtained via complexation of in situ CuII,Na-silsesquioxane species formed with phenanthroline and neocuproine. In the first case, phenanthroline, acting as "a silent ligand" (not participating in the composition of the final product), favors the formation of an unprecedented cagelike phenylsilsesquioxane of Cu9Na6 nuclearity, 1. In the second case, neocuproine ligands withdraws two Cu ions from the metallasilsesquioxane matrix, producing two cationic fragments Cu+(neocuproine)2. The remaining metallasilsesquioxane is rearranged into an anionic cage of Cu9Na4 nuclearity, finalizing the formation of a specific ionic complex, 2. The impressive molecular architecture of both types of complexes, e.g., the presence of different (cyclic/acyclic) types of silsesquioxane ligands, was established by single-crystal X-ray diffraction studies. Compound 1 was revealed to be highly active in the oxidative amidation of benzylic alcohol and the catalyst loading could be reduced down to 100 ppm of Cu. Catalytic studies of compound 1 demonstrated its high activity in hydroperoxidation of alkanes with H2O2 and oxidation of alcohols to ketones with tert-BuOOH.
- Astakhov, Grigorii S.,Bilyachenko, Alexey N.,Korlyukov, Alexander A.,Levitsky, Mikhail M.,Shul'Pina, Lidia S.,Bantreil, Xavier,Lamaty, Frédéric,Vologzhanina, Anna V.,Shubina, Elena S.,Dorovatovskii, Pavel V.,Nesterov, Dmytro S.,Pombeiro, Armando J. L.,Shul'Pin, Georgiy B.
-
supporting information
p. 11524 - 11529
(2018/09/13)
-
- Amorphous Cr/SiO2 Materials Hydrothermally Treated: Liquid Phase Cyclohexanol Oxidation
-
Abstract: Amorphous Cr–SiO2 materials were synthesized by the sol–gel method and hydrothermally treated at temperatures between 150 and 220?°C. These materials were used as catalysts for cyclohexanol oxidation with H2O2 as oxidant and CH3CN as a solvent. They were responsible for the decomposition of H2O2, which triggers, by a free?radical mechanism in the homogeneous phase, the oxidation or degradation of the hydrocarbon chain. Metal leaching causes a drop in catalytic activity when the material is recycled. Studies on the hydrothermal treatment effect on the leaching process have demonstrated that the higher the hydrothermal treatment temperature, the higher the metal/support interaction, leading to a diminution of the leaching process. Under mild reaction conditions, and using TBHP as oxidant, leaching was reduced, and improvements were obtained on the selectivity towards the formation of cyclohexanone. The use of these catalysts in the oxidation of verbenol, an allylic alcohol, showed a significant increase in the substrate conversion and in the selectivity to carbonyl derivative formation. Graphical Abstract: [Figure not available: see fulltext.].
- Miranda, José Feliciano,Cuesta Zapata, Pablo M.,Gonzo, Elio E.,Parentis, Mónica L.,Davies, Lilian E.,Bonini, Norberto A.
-
p. 2082 - 2094
(2018/05/28)
-
- Guaiacol Hydrogenation in an Aqueous Medium in the Presence of a Palladium Catalyst Supported on a Mesoporous Dendrimer-Containing Polymer
-
Guaiacol hydrogenation in an aqueous medium in the presence of a palladium catalyst supported on a mesoporous dendrimer-containing polymer and the effect of addition of sulfuric acid to the catalyst system have been studied. It has been found that the main hydrogenation product is 2-methoxycyclohexanol. After the addition of sulfuric acid to the catalyst system, the reaction mechanism significantly changes and cyclohexanol becomes the main hydrogenation product.
- Karakhanov,Boronoev,Filippova, T. Yu.,Maksimov
-
p. 407 - 411
(2018/05/28)
-
- Ni3P as a high-performance catalytic phase for the hydrodeoxygenation of phenolic compounds
-
The catalytic performance of an unsupported Ni2P in the aqueous phase hydrodeoxygenation (HDO) of phenol was investigated. It was found that the unsupported Ni2P was water-sensitive, being transformed stepwise, first to an amorphous phase and then to Ni5P2 and Ni12P5, and finally to Ni3P in the presence of water at elevated temperatures. Nonetheless, the generated Ni3P phase exhibited extraordinary hydrogenation activity at low temperatures and high HDO activity at high temperatures. The unsupported Ni3P was more active for the hydrogenation of the aromatic ring in the phenol molecule than Pd/SiO2 (1.0 wt%). The unsupported Ni3P was catalytically active and stable in phenol HDO in both the aqueous phase and the organic phase. In addition to phenol, catechol and o-cresol were investigated in the HDO catalyzed by the unsupported Ni3P in both aqueous solution and decalin solution. The HDO reactivity decreased in the order of phenol > catechol > o-cresol in the aqueous phase, and in the order of phenol > o-cresol in the organic phase (catechol is insoluble in decalin). In the oil phase HDOs of phenol and o-cresol, the unsupported Ni3P exhibited superior hydrogenation activity to that of the unsupported Ni2P at low temperatures.
- Yu, Zhiquan,Wang, Yao,Sun, Zhichao,Li, Xiang,Wang, Anjie,Camaioni, Donald M.,Lercher, Johannes A.
-
supporting information
p. 609 - 619
(2018/02/14)
-
- Synthesis, characterization, and catalytic oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene by recyclable polymer-grafted Schiff base complexes of vanadium(IV)
-
Schiff base-functionalized chloromethylated polystyrenes, PS-[Ae-Eol] (I), PS-[Hy-Eda] (II) and PS-[HyP-Eda] (III), were synthesized by reacting 2-(2-aminoethoxy)ethanol (Ae-Eol), N-(2-hydroxyethyl)ethylenediamine (Hy-Eda), and N-(2-hydroxpropyl)ethylened
- Singh, Vijay Kumar,Maurya, Abhishek,Kesharwani, Neha,Kachhap, Payal,Kumari, Sweta,Mahato, Arun Kumar,Mishra, Vivek Kumar,Haldar, Chanchal
-
p. 520 - 541
(2018/02/26)
-
- Continuous-Flow Palladium-Catalyzed Synthesis of Cyclohexanones from Phenols using Sodium Formate as a Safe Hydrogen Source
-
We report a procedure for the continuous-flow production of cyclohexanone from phenol on the basis of the use of sodium formate as a biomass-derived source of hydrogen and Pd/C as an easily accessible catalyst system. The reaction worked in water at pH 12.0 at 90 °C. By setting a packed reactor charged with the Pd/C catalyst (10 wt %) at a flow rate of 0.5 mL min?1, we achieved continuous-flow production of cyclohexanone in high yield with high selectivity and productivity.
- Valentini, Federica,Santillo, Niccolò,Petrucci, Chiara,Lanari, Daniela,Petricci, Elena,Taddei, Maurizio,Vaccaro, Luigi
-
p. 1277 - 1281
(2018/02/23)
-
- Mediated electrolysis of vicinal diols by neocuproine palladium catalysts
-
Synthetic electrochemistry agrees well with the principles of sustainable chemistry, therefore it is considered as a more environmentally friendly approach than some current synthetic methods. Here, we present a new strategy for the chemoselective oxidation of vicinal diols, viz. the integration of neocuproine palladium catalysts and electrosynthesis. Benzoquinones are used as an effective mediator as the reduced species (hydroquinones) can be easily reoxidized at relative low potentials at an electrode surface. NeocuproinePd(OAc)2 efficiently works as a catalyst in an electrolysis reaction for vicinal diols at room temperature. This is a remarkable observation given the fact that aerobic oxidation reactions of alcohols typically need a more complex catalyst, i.e. [neocuproinePdOAc]2[OTf]2. In this article we describe the optimization of the electrolysis conditions for the neocuproinePd(OAc)2 catalyst to selectively oxidize diols. The suggested approach leads to conversion of alcohols with high yields and provides an interesting alternative to perform oxidation reactions under mild conditions by the aid of electrochemistry.
- Lybaert,Tehrani, K. Abbaspour,De Wael
-
p. 685 - 691
(2017/07/22)
-
- Oxidation of Vicinal Diols to α-Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst
-
α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to α-hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions.
- Mecozzi, Francesco,Dong, Jia Jia,Saisaha, Pattama,Browne, Wesley R.
-
supporting information
p. 6919 - 6925
(2017/12/26)
-
- Ligustrazine-fused cyclic compound and medicine composition thereof, as well as application in medicine thereof
-
The invention discloses a ligustrazine-fused cyclic compound and a medicine composition thereof and application in a medicine. The ligustrazine-fused cyclic compound has the following structural general formula I: as shown in the specification. The medicine composition is a medicinal active component for the ligustrazine-fused cyclic compound and a pharmaceutically acceptable carrier, an excipient, a diluent, an adjuvant, a medium or a combination thereof; the ligustrazine-fused cyclic compound and the medicine composition can be used for preventing or treating cardiovascular and cerebrovascular diseases, digestive system diseases, respiratory diseases, the alzheimer's disease, kidney diseases and complications of the above-mentioned diseases due to thrombus and excessive free radicals. The ligustrazine-fused cyclic compound disclosed by the invention has an extremely good inhibition effect on in vitro ADP (adenosine diphosphate)-induced platelet aggregation; meanwhile, compared with the pharmacokinetic property of ligustrazine serving as a female parent, the pharmacokinetic property of the ligustrazine-fused cyclic compound in the body of a rat is obviously improved.
- -
-
Paragraph 0038; 0039; 0040; 0042
(2017/07/21)
-
- Synthesis of AgWCNx Nanocomposites for the One-Step Conversion of Cyclohexene to Adipic Acid and Its Mechanistic Studies
-
A novel catalyst composed of silver nanoparticles grafted on WCNx has been prepared by using a facile pH-adjusted method. The material reported in this study presents a non-mineral acid route for the synthesis of the industrially significant monomer adipic acid through the selective oxidation of cyclohexene. Ag has been stabilized in the hydrophobic matrix during the formation of the mesoporous silica material by using aniline as stabilizing agent. A cyclohexene conversion of 92.2 % with 96.2 % selectivity for adipic acid was observed with the AgWCNx-2 catalyst, therefore, the AgWCNx catalyst was found to be efficient for the direct conversion to adipic acid with respect to their monometallic counterparts. The energy profile diagrams for each reaction path by using the AgWCNx catalyst were studied along with their monometallic counterparts by using the Gaussian 09 package. The reported material can avoid the use of harmful phase-transfer catalysts (PTC) and/or chlorinated additives, which are two among other benefits of the reported work.
- Goyal, Reena,Sameer, Siddharth,Sarkar, Bipul,Bag, Arijit,Singhal, Nikita,Bordoloi, Ankur
-
p. 16555 - 16565
(2017/11/10)
-
- Oxidation of Cyclohexene in the Presence of Transition-Metal-Substituted Phosphotungstates and Hydrogen Peroxide: Catalysis and Reaction Pathways
-
Homogeneous catalytic oxidations of cyclohexene by transition-metal-substituted phosphotungstates [PW11M(L)O39]m? (PW11M, M=CoII, CuII, FeIII, NiII, MnII, L=H2O or absence) with hydrogen peroxide in acetonitrile were experimentally studied. The catalytic activities of allylic oxidation were found to strongly depend on the transition metals, and PW11Co showed the highest activity. The product distribution and the catalyst stability were dominated by mole ratio of hydrogen peroxide to PW11M, whereby low or high mole ratios led to stable structure of PW11M and predominant formation of allylic oxidation products or decomposition of PW11M, respectively. Different from the activation of the allylic C?H bond by radicals, the oxidation of C=C double bond was based on tungsten-peroxo species. A reaction mechanism composed of radical and nonradical processes was proposed from NMR, EPR, and kinetic data, to describe the reaction pathways of cyclohexene oxidation.
- Song, Yuexiao,Xin, Feng,Zhang, Lexiang,Wang, Yong
-
p. 4139 - 4147
(2017/11/15)
-
- A Pd/Monolayer Titanate Nanosheet with Surface Synergetic Effects for Precise Synthesis of Cyclohexanones
-
A catalyst composed of monolayer nonstoichiometric titanate nanosheets (denoted as TN) and Pd clusters is constructed for precise synthesis of cyclohexanone from phenol hydrogenation with high conversion (>99%) and selectivity (>99%) in aqueous media under light irradiation. Experimental and DFT calculation results reveal that the surface exposed acid and basic sites on TN could interact with phenol molecules in a nonplanar fashion via a hexahydroxy hydrogen-bonding ring to form a surface coordination species. This greatly facilitates the adsorption and activation of phenol molecules and suppresses the further hydrogenation of cyclohexanone. Moreover, the surface Pd clusters serve as the active sites for the adsorption and dissociation of hydrogen molecules to provide active H atoms. The synergistic effect of the surface coordination species, TN and Pd clusters remarkably facilitate the high yield of cyclohexanone in photocatalysis. Finally, the possible thermo/photocatalytic mechanisms on Pd/TN are proposed. This work not only highlights the great potential for monolayer nonstoichiometric composition nanosheets in the construction of catalysts for precise organic synthesis but also provides insight into the inherent catalytic behavior at a molecular level.
- Song, Yujie,Wang, Hao,Gao, Xiaomei,Feng, Yingxin,Liang, Shijing,Bi, Jinhong,Lin, Sen,Fu, Xianzhi,Wu, Ling
-
p. 8664 - 8674
(2017/12/08)
-
- NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates
-
New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(η3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4-trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1-(pyridin-2-yl)propan-2-one provided the β-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.
- Martinez-Espinar, Francisco,Blondeau, Pascal,Nolis, Pau,Chaudret, Bruno,Claver, Carmen,Castillón, Sergio,Godard, Cyril
-
p. 113 - 127
(2017/09/08)
-
- Whole-Cell-Catalyzed Multiple Regio- and Stereoselective Functionalizations in Cascade Reactions Enabled by Directed Evolution
-
Biocatalytic cascade reactions using isolated stereoselective enzymes or whole cells in one-pot processes lead to value-added chiral products in a single workup. The concept has been restricted mainly to starting materials and intermediate products that are accepted by the respective wild-type enzymes. In the present study, we exploited directed evolution as a means to create E. coli whole cells for regio- and stereoselective cascade sequences that are not possible using man-made catalysts. The approach is illustrated using P450-BM3 in combination with appropriate alcohol dehydrogenases as catalysts in either two-, three-, or four-step cascade reactions starting from cyclohexane, cyclohexanol, or cyclohexanone, respectively, leading to either (R,R)-, (S,S)-, or meso-cyclohexane-1,2-diol. The one-pot conversion of cyclohexane into (R)- or (S)-2-hydroxycyclohexanone in the absence of ADH is also described.
- Li, Aitao,Ilie, Adriana,Sun, Zhoutong,Lonsdale, Richard,Xu, Jian-He,Reetz, Manfred T.
-
supporting information
p. 12026 - 12029
(2016/11/16)
-
- The reaction of α-halocarbonyl compounds with (NH4)OH, (NH4)So4 or NH4CI solution under microwave-irradiation
-
Reaction of α-halo ketone (a-bromo ketone) under microwave, irradiation gives the pyrazine and quinoxaline derivative in good yields. This reaction affords a clean and convenient synthetic method for pyrazine and quinoxaline derivatives.
- Utsukihara, Takamitsu,Koshimura, Masahiro,Kitsuta, Kazunori,Sato, Akinori,Matsushita, Masatoshi,Takahashi, T. Tomoyoshi,Horiuchi, C. Akira
-
p. 1495 - 1502
(2017/11/10)
-
- An investigation on the aqueous-phase hydrodeoxygenation of various methoxy-substituted lignin monomers on Pd/C and HZSM-5 catalysts
-
Aqueous phase catalytic upgrading of lignin monomers to hydrocarbons via hydrodeoxygenation (HDO) has been explored using a combination of Pd/C and HZSM-5 catalysts under 2 MPa of H2 (ambient temperature). Model monomers with varying numbers of methoxy groups, including phenol, anisole, guaiacol and 2,6-dimethoxy-phenol, were chosen as lignin model compounds. Mechanistic studies revealed cascade and parallel reaction pathways via hydrogenation and dehydration (hydrolysis) processes, which were catalyzed by Pd/C and HZSM-5, respectively. Hydrogenation was preferred at lower temperature, whereas higher temperature was favorable for the removal of oxygen-containing functional groups. The effect of methoxy groups on the HDO of these monomers was also investigated systematically. Basically, the conversion of multi-substituted monomers was tougher than that of mono-substituted ones, due to steric constraint and the inhibition of the electron-donating hydroxyl group. The selectivities to cyclohexane from phenol and anisole were improved significantly by increasing the temperature to 413 K. However, cyclohexanone was preferably produced over cyclohexane when using model compounds with multi-substituents (guaiacol and 2,6-dimethoxy-phenol), even at temperatures above 513 K. Comparative experiments were also conducted on the HDO of 1,2-cyclohexanediol with or without the presence of phenol, which clearly suggested that the further HDO of guaiacol and 2,6-dimethoxy-phenol was inhibited, probably due to the strong interactions between cyclohexanediol molecules and Br?nsted acid sites.
- Zhang, Cong,Qi, Jingbo,Xing, Jing,Tang, Si-Fu,Song, Liang,Sun, Yuanyuan,Zhang, Chuanhui,Xin, Hongchuan,Li, Xuebing
-
p. 104398 - 104406
(2016/11/17)
-
- Robustly supported rhodium nanoclusters: Synthesis and application in selective hydrogenation of lignin derived phenolic compounds
-
The stabilization of small rhodium nanoclusters (NCs) in a polymer derived silicon carbonitride (SiCN) matrix has been reported to generate highly robust and active solid catalysts for the selective hydrogenation of phenolic compounds. An aminopyridinato Rh complex was used to modify a preceramic polymer (HTT 1800) followed by its pyrolysis at 1100 °C to afford small Rh NCs nicely dispersed over dense SiCN ceramic. For the synthesis of porous catalysts containing Rh NCs, microphase separation (followed by pyrolysis) of a diblock copolymer of HTT 1800 with hydroxy-polyethylene (PE-OH) was used. Both catalysts exhibit high activity in the hydrogenation of substituted phenols at room temperature and under low hydrogen pressure. The catalysts remained highly active and selective for six consecutive catalytic runs.
- Fehn, Sonja,Zaheer, Muhammad,Denner, Christine E.,Friedrich, Martin,Kempe, Rhett
-
p. 9252 - 9256
(2016/11/11)
-
- Heterometallic Metal-Organic Frameworks That Catalyze Two Different Reactions Sequentially
-
A series of copper- and alkaline-earth-metal-based multidimensional metal-organic frameworks, {[CuMg(pdc)2(H2O)4]·2H2O}n (1), [CuCa(pdc)2]n (2), [CuSr(pdc)2(H2O)3]n (3), and {[Cuba(pdc)2(H2O)5]·H2O}n (4), where H2Pdc = pyridine-2,5-dicarboxylic acid, were hydrothermally synthesized and characterized. Two different metals act as the active center to catalyze two kinds of reactions, viz., olefin to its epoxide followed by epoxide ring opening to afford the corresponding vicinal diol in a sequential manner.
- Saha, Debraj,Hazra, Dipak K.,Maity, Tanmoy,Koner, Subratanath
-
supporting information
p. 5729 - 5731
(2016/07/06)
-
- Oxidative Cleavage of Vicinal Diols with the Combination of Platinum and Vanadium Catalysts and Molecular Oxygen
-
The combination of Pt/C and V2O5 catalysts gave good performance for the oxidative cleavage of trans-1,2-cyclohexanediol into adipic acid via 2-hydroxycyclohexanone. The yield of adipic acid reached 90 % in the one-pot oxidative cleavage of trans-1,2-cyclohexanediol. The yield was higher than that obtained in the oxidation of 2-hydroxycyclohexanone with V catalyst, and the higher yield was due to the low 2-hydroxycyclohexanone concentration during the one-pot oxidation of trans-1,2-cyclohexanediol. Cyclic vicinal diols having a six-membered ring and linear vicinal diols having two secondary OH groups were converted into dicarboxylic acids and two carboxylic acids, respectively. The activity of the Pt catalyst decreased during the reaction, and the activity was partially restored by treating the used catalyst with H2 at 573K. Even without regeneration, the turnover number based on total Pt could reach ≈1000 in a long reaction with an increased amount of trans-1,2-cyclohexanediol.
- Obara, Naoyuki,Hirasawa, Shota,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
-
p. 1732 - 1738
(2016/05/19)
-
- From DNA to catalysis: A thymine-acetate ligated non-heme iron(III) catalyst for oxidative activation of aliphatic C-H bonds
-
A non-heme, iron(iii)/THA(thymine-1-acetate) catalyst together with H2O2 as an oxidant is efficient in oxidative C-H activation of alkanes. Although having a higher preference for tertiary C-H bonds, the catalyst also oxidizes aliphatic secondary C-H bonds into carbonyl compounds with good to excellent conversions. Based on the site selectivity of the catalyst and our mechanistic studies the reaction proceeds via an Fe-oxo species without long lived carbon centered radicals.
- Al-Hunaiti, Afnan,R?is?nen, Minn?,Repo, Timo
-
p. 2043 - 2046
(2016/02/05)
-
- Regio- and enantioselective reduction of diketones: Preparation of enantiomerically pure hydroxy ketones catalysed by Candida parapsilosis ATCC 7330
-
Enantiomerically enriched hydroxy ketones were prepared by the reduction of the corresponding diketones with excellent enantiomeric excess (98%) and in good yields (up to 75%) using whole cells of Candida parapsilosis ATCC 7330. Cyclic diketones, such as 1,2-cyclohexanedione and 1,4-cyclohexanedione, resulted in hydroxy ketones as products. Cyclohexane-1,3-dione and 5,5-dimethylcyclohexane-1,3-dione gave dimerised products, such as 2,2′-(ethane-1,1-diyl)bis(3-hydroxycyclohex-2-enone) and 2,2′-(ethane-1,1-diyl)bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) with acetaldehyde generated in situ from whole cells of Candida parapsilosis ATCC 7330, which is reported here for the first time.
- Mahajabeen, Pula,Chadha, Anju
-
p. 1167 - 1173
(2015/10/28)
-
- Silver nanoparticles supported on silica-coated ferrite as magnetic and reusable catalysts for oxidant-free alcohol dehydrogenation
-
Silver (0) nanoparticles supported on silica-coated ferrite were synthesized to be used as an efficient and recyclable heterogeneous catalyst for oxidant-free dehydrogenation of alcohols to the corresponding carbonyl compounds. The catalyst can be easily recovered and reused for 8 reaction cycles without considerable loss of activity. The facile recovery of the catalyst is carried out by applying an external magnetic device. The catalyst was fully characterized by the techniques of TEM, SEM, XRD, EDS, ICP-AES, and VSM. This journal is
- Bayat, Ahmad,Shakourian-Fard, Mehdi,Ehyaei, Nona,Mahmoodi Hashemi, Mohammad
-
p. 22503 - 22509
(2015/03/14)
-
- Enantioselective Cascade Biocatalysis via Epoxide Hydrolysis and Alcohol Oxidation: One-Pot Synthesis of (R)-α-Hydroxy Ketones from Meso- or Racemic Epoxides
-
A new type of cascade biocatalysis was developed for one-pot enantioselective conversion of a meso- or racemic epoxide to an α-hydroxy ketone in high ee via an epoxide hydrolase-catalyzed hydrolysis of the epoxide, an alcohol dehydrogenase-catalyzed oxidation of the diol intermediate, and an enzyme-catalyzed cofactor regeneration. In vitro cascade biotransformation of meso-epoxides (cyclopentene oxide 1a, cyclohexene oxide 1b, and cycloheptene oxide 1c) was achieved with cell-free extracts containing recombinant SpEH (epoxide hydrolase from Sphingomonas sp. HXN-200), BDHA (butanediol dehydrogenase from Bacillus subtilis BGSC1A1), and LDH (lactate dehydrogenase form Bacillus subtilis) or NOX (NADH oxidase from Lactobacillus brevis DSM 20054), respectively, giving the corresponding (R)-α-hydroxycyclopentanone 3a, (R)-α-hydroxycyclohexanone 3b, and (R)-α-hydroxycycloheptanone 3c in 98-99% ee and 70-50% conversion with TTN of NAD+-recycling of 5500-26000. Cascade catalysis with mixed cells of Escherichia coli (SpEH) and E. coli (BDHA-NOX) converted 100-300 mM meso-epoxides 1a-1c to (R)-α-hydroxy ketones 3a-3c in 98-99% ee and 85-57% conversion. Cells of E. coli (SpEH-BDHA-NOX) coexpressing all three enzymes were also proven as good catalysts for the cascade conversion of 100-200 mM meso-epoxides 1a-1c, giving (R)-α-hydroxy ketones 3a-3c in 98-99% ee and 79-52% conversion. The cascade biocatalysis for one-pot synthesis of α-hydroxy ketone in high ee was also successfully demonstrated with a racemic epoxide (1,2,3,4-tetrahydronaphthalene-1,2-oxide 1d) as the substrate. By using two whole-cells based approaches, (R)-α-hydroxytetralone 3d was obtained in 99% ee and 49-40% conversion from 20 to 5 mM racemic epoxide 1d. Preparative cascade biotransformation of cyclohexene oxide 1b gave (R)-α-hydroxycyclohexanone 3b in 98% ee with 70% isolated yield. The developed new type of cascade biocatalysis is enantioselective, green, and often high yielding. The concept might be generally applicable to produce other useful enantiopure α-hydroxy ketones from the corresponding meso- or racemic epoxides by cascade catalysis using appropriate enzymes. (Chemical Equation Presented).
- Zhang, Jiandong,Wu, Shuke,Wu, Jinchuan,Li, Zhi
-
-
- Efficient room-temperature aqueous-phase hydrogenation of phenol to cyclohexanone catalyzed by Pd nanoparticles supported on mesoporous MMT-1 silica with unevenly distributed functionalities
-
Efficient and selective aqueous-phase hydrogenation of phenol by a novel Pd catalyst supported on dually and selectively functionalized mesoporous MMT-1 silica nanoparticles has been developed. The catalyst features small (~1.1 nm) Pd nanoparticles surrounded by unevenly distributed nitrogen- or heteroatom-free organic groups in the helical mesopores and the presence of non-hydrogen-bonded isolated silanol groups on the mesopore surface. The catalyst exhibited superior conversion of phenol and high selectivity of cyclohexanone at room temperature under atmospheric pressure of hydrogen and remained highly active after ten catalytic runs. The catalyst was active for the aqueous-phase hydrogenation of a variety of mono- and dihydroxylated aromatic compounds. The green protocol with the designed catalyst would be practical for the hydrogenation of phenol and other derivatives.
- Lin, Chi-Jui,Huang, Shao-Hsien,Lai, Nien-Chu,Yang, Chia-Min
-
p. 4121 - 4129
(2015/11/11)
-
- Fabrication of Ag/WO3 nanobars for Baeyer-Villiger oxidation using hydrogen peroxide
-
We report the preparation of Ag/WO3 nanobars, mediated by cationic surfactant CTAB through hydrothermal route. XRD revealed the formation of metallic Ag supported on monoclinic WO3 phase and TEM diagram showed the formation of bar-like structure, where supported Ag nanoparticles are in the range between 2 and 7 nm. The catalyst exhibited high activity for selective oxidation of cyclohexanone to caprolactone with H2O2. A cyclohexanone conversion of 97% with 99% caprolactone selectivity was achieved over this catalyst at 80°C temperature. Moreover, the catalyst did not show any significant activity loss even after 5 reuses and proved its efficiency in the oxidation of other cycloalkanones also.
- Ghosh, Shilpi,Acharyya, Shankha Shubhra,Singh, Raghuvir,Gupta, Piyush,Bal, Rajaram
-
-
- Catalytic Oxidation of Alkanes and Alkenes by H2O2 with a μ-Oxido Diiron(III) Complex as Catalyst/Catalyst Precursor
-
A new μ-oxo diiron(III) complex of the lithium salt of the pyridine-based unsymmetrical ligand 3-[(3-{[bis(pyridin-2-ylmethyl)amino]methyl}-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino]propanoate (LiDPCPMPP), [Fe2(μ-O)(LiDPCPMPP)2](ClO4)2, has been synthesized and characterized. The ability of the complex to catalyze oxidation of several alkanes and alkenes has been investigated by using CH3COOH/H2O2 (1:1) as an oxidative system. Moderate activity in cyclohexane oxidation (TOF = 33 h-1) and good activity in cyclohexene oxidation (TOF = 72 h-1) were detected. Partial retention of configuration (RC = 53%) in cis- and trans-1,2-dimethylcyclohexane oxidation, moderate 3/2 selectivity (4.1) in adamantane oxidation, and the observation of a relatively high kinetic isotope effect for cyclohexane oxidation (KIE = 3.27) suggest partial metal-based oxidation, probably in tandem with free-radical oxidation. Low-temperature UV/Vis spectroscopy and mass spectrometric studies in the rapid positive detection mode indicate the formation of a transient peroxido species, [Fe2(O)(O2)(LiDPCPMPP)2]2+, which might be an intermediate in the metal-based component of the oxidation process. A μ-oxido diiron(III) complex, [Fe2(μ-O)(LiDPCPMPP)2](ClO4)2, was synthesized and characterized. This complex was used as catalyst in C-H bond oxidation with CH3COOH-H2O2 as chemical oxidant. Reactivity studies indicate that the oxidation process goes through a metal-based mechanism concomitant with a radical process.
- Das, Biswanath,Al-Hunaiti, Afnan,Haukka, Matti,Demeshko, Serhiy,Meyer, Steffen,Shteinman, Albert A.,Meyer, Franc,Repo, Timo,Nordlander, Ebbe
-
p. 3590 - 3601
(2015/08/06)
-