- In silico, cytotoxic and antioxidant potential of novel ester, 3-hydroxyoctyl -5- trans-docosenoate isolated from anchusa arvensis (L.) m.bieb. against hepg-2 cancer cells
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Background: Cancer is one of the chronic health conditions worldwide. Various therapeutically active compounds from medicinal plants were the current focus of this research in order to uncover a treatment regimen for cancer. Anchusa arvensis (A. anchusa) (L.) M.Bieb. contains many biologically active compounds. Methods: In the current study, new ester 3-hydroxyoctyl-5-trans-docosenoate (compound-1) was isolated from the chloroform soluble fraction of A. anchusa using column chromato-graphy. Using MTT assay, the anticancer effect of the compound was determined in human hepatocellular carcinoma cells (HepG-2) compared with normal epithelial cell line (Vero). DPPH and ABTS radical scavenging assays were performed to assess the antioxidant potential. The Molecular Operating Environment (MOE-2016) tool was used against tyrosine kinase. Results: The structure of the compound was elucidated based on IR, EI, and NMR spectroscopy technique. It exhibited a considerable cytotoxic effect against HepG-2 cell lines with IC50 value of 6.50 ± 0.70 μg/mL in comparison to positive control (doxorubicin) which showed IC50 value of 1.3±0.21 μg/mL. The compound did not show a cytotoxic effect against normal epithelial cell line (Vero). The compound also exhibited significant DPHH scavenging ability with IC50 value of 12 ± 0.80 μg/mL, whereas ascorbic acid, used as positive control, demonstrated activity with IC50 = 05 ± 0.15 μg/mL. Similarly, it showed ABTS radical scavenging ability (IC50 = 130 ± 0.20 μg/mL) compared with the value obtained for ascorbic acid (06 ± 0.85 μg/mL). In docking studies using MOE-2016 tool, it was observed that compound-1 was highly bound to tyrosine kinase by having two hydrogen bonds at the hinge region. This good bonding network by the compound might be one of the reasons for showing significant activity against this enzyme. Conclusion: Our findings led to the isolation of a new compound from A. anchusa which has significant cytotoxic activity against HepG-2 cell lines with marked antioxidant potential.
- Hussain, Sajid,Ullah, Farhat,Ayaz, Muhammad,Ali Shah, Syed Adnan,Shah, Azhar-Ul-Haq Ali,Shah, Syed Majid,Wadood, Abdul,Aman, Waqar,Ullah, Riaz,Shahat, Abdelaaty A.,Nasr, Fahd A.
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Read Online
- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- On/Off O2 Switchable Photocatalytic Oxidative and Protodecarboxylation of Carboxylic Acids
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Photoredox catalysis in recent years has manifested a powerful branch of science in organic synthesis. Although merging photoredox and metal catalysts has been a widely used method, switchable heterogeneous photoredox catalysis has rarely been considered. Herein, we open a new window to use a switchable heterogeneous photoredox catalyst which could be turned on/off by changing a simple stimulus (O2) for two opponent reactions, namely, oxidative and protodecarboxylation. Using this strategy, we demonstrate that Au@ZnO core-shell nanoparticles could be used as a switchable photocatalyst which has good catalytic activity to absorb visible light due to the localized surface plasmon resonance effect of gold, can decarboxylate a wide range of aromatic and aliphatic carboxylic acids, have multiple reusability, and are a reasonable candidate for synthesizing both aldehydes/ketones and alkane/arenes in a large-scale set up. Some biologically active molecules are also shown via examples of the direct oxidative and protodecarboxylation which widely provided pharmaceutical agents.
- Bazyar, Zahra,Hosseini-Sarvari, Mona
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p. 13503 - 13515
(2019/10/11)
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- Pillar5arenes as Supramolecular Hosts in Aqueous Biphasic Rhodium-Catalyzed Hydroformylation of Long Alkyl-chain Alkenes
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Aqueous biphasic catalysis continues to attract strong interest, especially when very hydrophobic substrates are concerned. Indeed, their insolubility in water strongly limit their transformation by water-soluble organometallic catalysts. To improve contacts between the substrate-containing organic phase and the catalyst-containing phase, one of the best solutions consists in using interfacial additives capable of supramolecularly recognize the substrate and/or the catalyst. In the present study, modified pillar5arenes are considered as interfacial additives and their performance is assessed in Rh-catalyzed hydroformylation of long alkyl-chain alkenes (higher olefins). Pillar5arenes substituted by carboxylate functions and methyl groups P5 A-(Me)10-x-(CH2COOMe)x are compared to pillar5arenes substituted by polyethylene glycol (PEG) chains (P5 A-(Me)5-(PEG)5 and P5 A-(PEG)10). Utilization of P5 A-(Me)10-x-(CH2COOMe)x leads to high conversion and regioselectivity (linear/branched aldehyde ratio) in Rh-catalyzed hydroformylation of 1-decene and 1-hexadecene. Compared with other interfacial additives such as modified cyclodextrins, the studied pillar5arenes show lower chemo-selectivity, similar catalytic activity and higher regioselectivity.
- Benatmane, Missipssa,Cousin, Kévin,Laggoune, Nérimel,Menuel, Stéphane,Monflier, Eric,Woisel, Patrice,Hapiot, Frédéric,Potier, Jonathan
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p. 5306 - 5313
(2018/11/10)
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- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
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Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
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supporting information
p. 10164 - 10167
(2018/09/13)
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- Water-soluble phosphane-substituted cyclodextrin as an effective bifunctional additive in hydroformylation of higher olefins
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In cyclodextrin (CD)-mediated aqueous biphasic catalysis, favoring contacts between the CD ("host"), the organic substrate ("guest") and the water-soluble catalyst is crucial for the reaction to proceed efficiently at the aqueous/organic interface. Grafting the catalyst onto the CD backbone thus appears as an attractive approach to favor the molecular recognition of the substrate and its subsequent catalytic conversion into products. In this context, a new water-soluble β-CD-based phosphane was synthesized and characterized by NMR, tensiometric and ITC measurements. The β-CD-based phosphane consisted of a 3,3′-disulfonatodiphenyl phosphane connected to the primary face of β-CD by a dimethyleneamino spacer. Intra- and intermolecular inclusion processes of one of the two sulfophenyl groups into the β-CD cavity were identified in water. However, the association constant (Ka) related to the β-CD/sulfophenyl group couple was low. Accordingly, the inclusion process was easily displaced upon coordination to rhodium complexes. The efficacy of the resulting Rh-complex coordinated by β-CD-based phosphanes was assessed in Rh-catalyzed hydroformylation of higher olefins. The catalytic system proved to be far more successful and efficient than a system consisting of supramolecularly interacting phosphanes and CDs. The catalytic activity was up to 30-fold higher while the chemo- and regioselectivities remain rather unchanged.
- Leblond,Potier,Menuel,Bricout,Machut-Binkowski,Landy,Tilloy,Monflier,Hapiot
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p. 3823 - 3830
(2017/09/07)
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- Sequential reactions from catalytic hydroformylation toward the synthesis of amino compounds
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Different families of new amino compounds were efficiently synthesized, through optimized sequential processes, involving rhodium catalyzed hydroformylation as the key step. The selection of appropriate hydroformylation catalytic systems and reaction conditions allowed obtaining aldehydes derived from several n-alkyl olefins, cholest-4-ene and 3-vinyl-1H-indole, which were subsequently transformed, in one-pot, in to α-amino acids via hydroformylation/Strecker reaction, and in to tertiary amines via hydroaminomethylation, with excellent yields.
- Almeida, Ana R.,Carrilho, Rui M.B.,Peixoto, Andreia F.,Abreu, Artur R.,Silva, Artur,Pereira, Mariette M.
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supporting information
p. 2389 - 2395
(2017/04/03)
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- Thermal stability, decomposition enthalpy, and Raman spectroscopy of 1-alkene secondary ozonides
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The synthesis of a series of 1-alkene secondary ozonides was monitored with Raman spectroscopy which is very effective in the detection of the O-O stretching band of the 1,2,4-trioxolane ring. The 1-alkene secondary ozonides thermal decomposition was studied with DSC (differential scanning calorimetry). For all ozonides studied the decomposition onset was found at about 106 °C and the decomposition peak at about 130 °C. The decomposition enthalpy ΔHdec of the secondary ozonides examined was found in the range of -313 to -347 kJ/mol. Despite the considerable amount of heat evolved, the decomposition was not explosive. The decomposition products of 1-octadecene ozonide were studied by TGA-FTIR (thermogravimetric analysis coupled with FT-infrared spectroscopy) and by GC-MS. The main products detected were formic acid and heptadecanal.
- Cataldo, Franco
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p. 994 - 998
(2015/02/19)
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- RP-HPLC-fluorescence analysis of aliphatic aldehydes: Application to aldehyde-generating enzymes HACL1 and SGPL1
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Long-chain aldehydes are commonly produced in various processes, such as peroxisomal α-oxidation of long-chain 3-methyl-branched and 2-hydroxy fatty acids and microsomal breakdown of phosphorylated sphingoid bases. The enzymes involved in the aldehyde-generating steps of these processes are 2-hydroxyacyl-CoA lyase (HACL1) and sphingosine-1-phosphate lyase (SGPL1), respectively. In the present work, nonradioactive assays for these enzymes were developed employing the Hantzsch reaction. Tridecanal (C13-al) and heptadecanal (C17-al) were selected as model compounds and cyclohexane-1,3-dione as 1,3-diketone, and the fluorescent derivatives were analyzed by reversed phase (RP)-HPLC. Assay mixture composition, as well as pH and heating, were optimized for C13-al and C17-al. Under optimized conditions, these aldehydes could be quantified in picomolar range and different long-chain aldehyde derivatives were well resolved with a linear gradient elution by RPHPLC. Aldehydes generated by recombinant enzymes could easily be detected via this method. Moreover, the assay allowed to document activity or deficiency in tissue homogenates and fibroblast lysates without an extraction step. In conclusion, a simple, quick, and cheap assay for the study of HACL1 and SGPL1 activities was developed, without relying on expensive mass spectrometric detectors or radioactive substrates. Copyright
- Mezzar, Serena,De Schryver, Evelyn,Van Veldhoven, Paul P.
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p. 573 - 582
(2014/03/21)
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- Synergetic effect of randomly methylated β-cyclodextrin and a supramolecular hydrogel in Rh-catalyzed hydroformylation of higher olefins
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A significant improvement in Rh-catalyzed hydroformylation of very hydrophobic alkenes was achieved using a biphasic catalytic system consisting of a substrate-containing organic phase and a catalyst-containing hydrogel phase [consisting of poly(ethylene glycol) 20000 (PEG20000) and α-cyclodextrin (α-CD)]. The catalytic performance of the Pickering emulsion that resulted from the formation of α-CD/PEG20000 crystallites at the oil droplet surface proved to be greatly dependent upon the presence of additives. We showed that controlled uploads of randomly methylated β-cyclodextrin (RAME-β-CD) within the supramolecular hydrogel could positively affect both the catalytic activity and chemoselectivity of the hydroformylation reaction. Conversely, no Pickering emulsion could be observed using excess RAME-β-CD, resulting in the subsequent degradation of the catalytic performance. Optical microscopy and optical fluorescence microscopy supported the catalytic results and allowed us to explain the role of RAME-β-CD. Indeed, controlled uploads of RAME-β-CD prevented the saturation of the oil droplet surface. RAME-β-CD acted as a fluidifier of the Pickering emulsion and accelerated the dynamics of exchange between the substrate-containing organic phase and the catalyst-containing hydrogel phase. Morever, RAME-β-CD acted as a receptor that participated in the conversion of the alkene by supramolecular means.
- Potier, Jonathan,Menuel, Stephane,Monflier, Eric,Hapiot, Frederic
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p. 2342 - 2346
(2014/07/21)
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- Pickering emulsions based on supramolecular hydrogels: Application to higher olefins' hydroformylation
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Supramolecular hydrogels elaborated from a mixture of native α-cyclodextrin and poly(ethylene glycol)s in water proved to be effective media for higher olefins Rh-catalyzed hydroformylation due to the formation of Pickering emulsions.
- Potier, Jonathan,Menuel, Stephane,Chambrier, Marie-Heleine,Burylo, Laurence,Blach, Jean-Francois,Woisel, Patrice,Monflier, Eric,Hapiot, Frederic
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p. 1618 - 1621
(2013/07/26)
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- A cyclodextrin dimer as a supramolecular reaction platform for aqueous organometallic catalysis
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A reaction platform based on a cyclodextrin dimer, which is able to simultaneously include a substrate in one cavity and an organometallic catalyst into the other, proved to be highly efficient for aqueous hydroformylation reaction of higher olefins.
- Blaszkiewicz, Claire,Bricout, Herve,Leonard, Estelle,Len, Christophe,Landy, David,Cezard, Christine,Djedaini-Pilard, Florence,Monflier, Eric,Tilloy, Sebastien
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supporting information
p. 6989 - 6991
(2013/09/02)
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- Selective hydroformylation of olefins over the rhodium supported large porous metal-organic framework MIL-101
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Highly porous and crystalline metal-organic framework MIL-101 has been synthesized and used for the preparation of rhodium supported catalyst. Acetylacetonato(1,5-cyclooctadiene)rhodium(I) has been used as catalyst precursor. The material has been characterized by XRD, XPS, SAXS, FTIR, SEM, TEM, AAS, and nitrogen adsorption. The catalytic properties of Rh@MIL-101 have been investigated in the hydroformylation of olefins with different structure and chain length to the corresponding aldehydes. High conversion and selectivity to n-aldehydes have been achieved in the hydroformylation of n-alk-1-enes. The obtained results show that the rhodium species are highly dispersed and preferentially located at internal and less accessible sites at the supertetrahedral units.
- Van Vu, Toan,Kosslick, Hendrik,Schulz, Axel,Harloff, Joerg,Paetzold, Eckhard,Schneider, Mathias,Radnik, Joerg,Steinfeldt, Norbert,Fulda, Gerhard,Kragl, Udo
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p. 410 - 417
(2013/10/22)
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- Room temperature ambient pressure (RTAP)-hydroformylation in water using a self-assembling ligand
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We herein demonstrate a hydroformylation at room temperature and ambient pressure (RTAP) using our Rh/6-DPPon (1) system in aqueous media. The hydrogen bonding network of the ligand backbone stays intact, exemplified by the excellent regioselectivity for the linear aldehyde. Various substrates with different functional groups (with some prone to hydrolysis) are stable under the applied conditions and can undergo hydroformylation resulting in good yields. Copyright
- Straub, Alexander T.,Otto, Marina,Usui, Ippei,Breit, Bernhard
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supporting information
p. 2071 - 2075
(2013/08/23)
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- Aqueous biphasic hydroformylation in the presence of cyclodextrins mixtures: Evidence of a positive synergistic effect
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Mixtures of randomly methylated cyclodextrins of various sizes have been evaluated in the rhodium-catalysed hydroformylation of higher olefins in an aqueous biphasic medium. A marked positive non-linear effect on 1-tetradecene conversion is observed when the CD molar ratio in the mixture is modified. The formation of 2:1 ternary inclusion complexes between RAME-CDs and the olefin is supposed to be responsible for the extra conversion observed. The Royal Society of Chemistry.
- Ferreira, Michel,Legrand, Francois-Xavier,MacHut, Cecile,Bricout, Herve,Tilloy, Sebastien,Monflier, Eric
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experimental part
p. 8643 - 8647
(2012/10/08)
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- METHOD FOR PRODUCING OXYGEN-CONTAINING COMPOUND
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[Problem] There is provided a method for producing an oxygen-containing compound safely and with improved reaction efficiency, in which an undesired peroxide is unlikely to be produced, and efficient heat exchange of the ozonization can be achieved. [Mean for solving the Problem] The method comprises an ozonization reaction step of continuously supplying, together with an organic compound, ozone having an oxygen content of less than 10% in a dissolved state in high-pressure carbon dioxide to an ozonization reaction section having a thin tubular shape, and reacting the ozone and the organic compound under conditions that suppress generation of oxygen due to thermal decomposition of the ozone, thereby continuously producing an ozonide; and a decomposition reaction step of continuously supplying the ozonide produced in the ozonization reaction step to a decomposition reaction section having a thin tubular shape, thereby continuously producing an oxygen-containing compound, the decomposition reaction step being provided in a manner continuous with the ozonization reaction step.
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Page/Page column 22-23
(2012/01/11)
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- Low-concentration ozone reacts with plasmalogen glycerophosphoethanolamine lipids in lung surfactant
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Ozone is a common environmental toxicant to which individuals are exposed to on a daily basis. While biochemical end points such as increased mortality, decrements in pulmonary function, and initiation of inflammatory processes are known, little is actually understood regarding the chemical mechanisms underlying changes in pulmonary health, especially for low concentrations of ozone. This study was undertaken to investigate ozone-induced oxidation of endogenous lipids that are potentially exposed to environmental ozone within lung, specifically focusing on plasmalogen glycerophospholipids present in pulmonary surfactant. Sensitive liquid chromatography - mass spectrometry methods were developed to follow oxidation of diacyl and plasmalogen phosphatidylethanolamine (PE) phospholipids and to identify and quantitate products generated by ozonolysis. Using a unilamellar vesicle system containing a 1:1 molar mixture of 1-O-octadec-1′-enyl-2-octadecenoyl-PE and 1,2-dihexadecanoyl-PC, these studies revealed that the vinyl ether bond of plasmalogens was oxidized preferentially at low concentrations of ozone (100 ppb), when compared to olefinic bond oxidation on ω-9 of the fatty acyl chain in the same phospholipids. Major phospholipid products generated were identified as 1-formyl-2-octadecenoyl-PE and 1-hydroxy-2-octadecenoyl-PE. Heptadecanal and heptadecanoic acid production was also quantitated using gas chromatography - mass spectrometry, and production was consistent with oxidation of the vinyl ether, at low concentrations of ozone. Analysis of murine lung surfactant from C57Bl/6 mice revealed several plasmalogen PE lipid species, encompassing ～38% of total PE species. Upon exposure of ozone (0 and 100 ppb) to murine surfactant, plasmalogen PE molecular species preferentially reacted, as compared to diacyl PE molecular species. Lysophospholipids, pentadecanal, and nonanal were found to be the primary products of surfactant ozone oxidation.
- Wynalda, Kelly M.,Murphy, Robert C.
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body text
p. 108 - 117
(2011/02/26)
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- Synthesis of enantiopure aliphatic acetylene alcohols and determination of their absolute configurations by 1H NMR anisotropy and/or X-ray crystallography
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The MαNP acid method has been applied to racemic aliphatic acetylene alcohols in order to simultaneously prepare enantiopure alcohols and to determine their absolute configurations by 1H NMR anisotropy. Racemic acetylene alcohols 6-8, 11, and 20 were esterified with MαNP acid (S)-(+)-1 to yield diastereomericMαNP esters which were efficiently separated by HPLC on silica gel with separation factors α in the range 1.60-1.93. The 1H NMR anisotropy factors Δδ [= δ(2nd fr.) - δ(1st fr.)] were calculated from the data of the first- (22a-27a) and second-eluted MαNP esters (22b-27b). The absolute configurations of the first-eluted esters were determined from the distribution of Δδ values in the MαNP sector rule. In the case of MαNP ester 26b, the assigned absolute configuration was confirmed by X-ray crystallography. The solvolysis of MαNP esters yielded enantiopure acetylene alcohols 5-8 with established absolute configurations. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Sekiguchi, Satoshi,Akagi, Megumi,Naito, Junpei,Yamamoto, Yoko,Taji, Hiromi,Kuwahara, Shunsuke,Watanabe, Masataka,Ozawa, Yoshiki,Toriumi, Koshiro,Harada, Nobuyuki
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experimental part
p. 2313 - 2324
(2009/04/05)
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- An efficient conversion of carboxylic acids to one-carbon degraded aldehydes via 2-hydroperoxy acids
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After the formation of dianions of a carboxylic acid with lithium diisopropylamide, oxygen was bubbled into the solution to produce 2-hydroperoxy acid. Then the reaction mixture was acidified with a 2N HCl solution and subsequently elevated to 50°C to afford the aldehyde with the loss of one carbon atom. Even saturated (C10-C20) and unsaturated (C18:1) carboxylic acids were converted into the odd aldehydes (C9-C19, C17:1) in high yields. This conversion was found to be an efficient method for the preparation of carboxylic acids (Cn) to one-carbon degraded aldehydes (Cn-1) via 2-hydroperoxy acids.
- Akakabe, Yoshihiko,Nyuugaku, Takeshi
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p. 1370 - 1371
(2008/02/07)
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- Sensory-directed identification of creaminess-enhancing volatiles and semivolatiles in full-fat cream
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Aimed at defining the chemical nature of creaminess-related flavor compounds in dairy products on a molecular level, a full-fat cream was analyzed for sensorially active volatiles and semivolatiles by means of activity-guided screening techniques. Application of the aroma extract dilution analysis on an aroma distillate prepared from pasteurized cream (30% fat) revealed δ-decalactone, (Z)-6-dodeceno-γ-lactone, γ-dodecalactone, δ-dodecalactone, and 3-methylindole with by far the highest flavor dilution (FD) factors among the 34 odor-active volatiles identified. Using a complementary approach involving silica column chromatography and fractionated high-vacuum distillation combined with sensory experiments enabled the additional identification of δ-tetradecalactone, δ-hexadecalactone, γ-tetradecalactone, γ-hexadecalactone, and δ-octadecalactone as semivolatile flavor components in the cream fat. Although a series of lactones is present in dairy cream, spiking of cream samples with individual lactones revealed that only the δ-tetradecalactone is able to enhance the typical retronasal creamy flavor of the product when added in amounts above its theshold level of 66 μmol/kg. Rather than contributing to the retronasal aroma of cream, first evidence was found that, particularly, γ- and δ-octadecalactones and γ- and δ-eicosalactones are able to influence the melting behavior of cream in the oral cavity.
- Schlutt, Birgit,Moran, Noelia,Schieberle, Peter,Hofmann, Thomas
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p. 9634 - 9645
(2008/03/17)
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- The synthesis of one enantiomer of the α-methyl-trans-cyclopropane unit of mycolic acids
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We report the synthesis of a single enantiomer of an α-methyl-trans-cyclopropane unit present in a number of mycolic acids and its incorporation into a reported 1,2-dialkylcyclopropane meromycolate that contains one cis-1,2-dialkylcyclopropane and one α-methyl-trans-1,2-dialkylcyclopropane.
- Al-Dulayymi, Juma'a R.,Baird, Mark S.,Mohammed, Hayder,Roberts, Evan,Clegg, William
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p. 4851 - 4862
(2007/10/03)
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- Catalyst-free oxidation of alcohols at room temperature using water as solvent
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An effective, cheap, environmentally benign and catalyst-free oxidation of alcohols was carried out at room temperature using tetra-n-butylammonium Oxone (TBA-OX) as oxidant with moderate to high selectivity for most of the alcohols using water as the solvent.
- Lei, Ziqiang,Yang, Yaoxia,Bai, Xiangzhen
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p. 877 - 880
(2007/10/03)
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- Bidentate ligands by self-assembly through hydrogen bonding: A general room temperature/ambient pressure regioselective hydroformylation of terminal alkenes
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The 6-DPPon (1)/rhodium catalyst allows for the first time a room temperature/ambient pressure regioselective hydroformylation of terminal alkenes with low catalyst loadings in good activity. The generality of this catalyst under these conditions was demonstrated for a wide range of structurally diverse alkenes equipped with many important functional groups. Thus, this practical and highly selective hydroformylation protocol, which omits the need for special pressure equipment, should find wide application in organic synthesis.
- Seiche, Wolfgang,Schuschkowski, Alexander,Breit, Bernhard
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p. 1488 - 1494
(2007/10/03)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- A well-defined complex for palladium-catalyzed aerobic oxidation of alcohols: Design, synthesis, and mechanistic considerations
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A breath of fresh air: A variety of alcohols are oxidized using 0.5-0.1 mol% of the catalyst, and in some cases the oxidation can simply be carried out open to the air (see scheme). Mechanistic insight into the mechanism is provided by a crystal structure that shows remarkable hydrogen bonds between the coordinated water and acetate ligands and an unprecedented large kinetic isotope effect.
- Jensen, David R.,Schultz, Mitchell J.,Mueller, Jaime A.,Sigman, Matthew S.
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p. 3810 - 3813
(2007/10/03)
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- A suite of novel allenes from Australian melolonthine scarab beetles. Structure, synthesis, and stereochemistry
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A suite of allenic hydrocarbons, previously unknown as a molecular class from insects, has been characterized from several Australian melolonthine scarab beetles. The allenes are represented by the formula CH3(CH2)nCH=·=CH (CH2)7CH3 with n being 11-15, 17 and 19, and thus, all have Δ9,10-unsaturation. These structures have been confirmed by syntheses and comparisons of spectral and chromatographic properties with those of the natural components. The enantiomers of (±) Δ9,10-tricosadiene and Δ9,10-pentacosadiene were separable on a modified β-cyclodextrin column (gas chromatography), and the natural Δ9,10-tricosadiene (n = 11) and Δ9,10-pentacosadiene (n = 13) were shown to be of >85% ee. Syntheses of nonracemic allenes of known predominating chirality were acquired using both organotin chemistry and sulfonylhydrazine intermediates, and comparisons then demonstrated that the natural allenes were predominantly (R)-configured.
- McGrath, Matthew J.,Fletcher, Mary T.,Koenig, Wilfried A.,Moore, Christopher J.,Cribb, Bronwen W.,Allsopp, Peter G.,Kitching, William
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p. 3739 - 3748
(2007/10/03)
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- New approaches to fluorinated ligands and their application in catalysis
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Simple and generic approaches to fluorous soluble ligands have been developed and applied to the synthesis of various fluorinated arylphosphines including polymeric ones. The utility of some of these ligands has been demonstrated in catalysis in supercritical CO2 (scCO2) and fluorous solvents.
- Chen, Weiping,Xu, Lijin,Hu, Yulai,Banet Osuna, Anna M,Xiao, Jianliang
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p. 3889 - 3899
(2007/10/03)
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- Catalytic activity enhancement of a cyclodextrin/water-soluble-rhodium complex system due to its gradual supramolecular organization in the interphase
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Heavy terminal alkenes can be hydroformylated at a significant rate by using the water-soluble catalyst precursor [Rh2(μStBu)2(CO)2(TPPTS)2] and β-cyclodextrin or its dimethylated form as phase-transfer agent. A study of the recycling has shown that the aqueous phase can be directly reintroduced into catalysis and also that each new run presents a slightly higher level of activity. Careful examination of the parameters of this catalysis leads us to propose that a gradual supramolecular organization in the interphase occurs for the rhodium complex, its solvation sphere and cyclodextrin which should involve at least two molecules in a head-to-tail or head-to-head arrangement.
- Dessoudeix, Michel,Urrutigoity, Martine,Kalck, Philippe
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p. 1797 - 1800
(2007/10/03)
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- PCC oxidation of organoboranes obtained using acetoxyborohydride
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The selective hydroboration with acetoxyborohydride of dienes and functionalized olefins followed by PCC oxidation afford the corresponding carbonyl derivatives.
- Dhillon, Ranjit S.,Kaur, Avinder Pal,Kaur, Gurpreet
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p. 453 - 454
(2007/10/03)
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- Effects of the Ponytails of Arylphosphines on the Hydroformylation of Higher Olefins in Supercritical CO2
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A series of ponytail-appended arylphosphines P(C6H4R-m)3 (m = 4, R = n-C6F13 1, n-CH2CH2C6F13 3, n-C6H13 4, n-C10H21 5 or n-C16H33 6; m = 3, R = n-C6F13 2) have been studied in the rhodium-catalysed hydroformylation of higher olefins in supercritical CO2 (scCO2), with the perfluoroalkylated ligands exhibiting the highest and the alkylated one the lowest activities. The high rates derived from 1 and 2 probably originate from the strong electron-withdrawing effect of their ponytails, while the slow rates observed with 4-6 are mainly due to the low solubility of these ligands in scCO2.
- Osuna, Anna M. Banet,Chen, Weiping,Hope, Eric G.,Kemmitt, Ray D. W.,Paige, Danny R.,Stuart, Alison M.,Xiao, Jianliang,Xu, Lijin
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p. 4052 - 4055
(2007/10/03)
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- Fluorous soluble polymer catalysts for the fluorous biphase hydroformylation of olefins
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Fluorous soluble polymer ligands have been prepared and shown to be active and selective catalysts when combined with rhodium for the fluorous biphase hydroformylation of various olefins.
- Chen, Weiping,Xu, Lijin,Xiao, Jianliang
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p. 839 - 840
(2007/10/03)
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- PREPARATION OF ALKYL HALIDES VIA ORGANOTELLURIUMS
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The conversion of phenyltelluroalkanes to haloalkanes was studied in connection with the homologation of alkyl halides.Similar reactions of 1,1-bis(phenyltelluro)alkanes provided a new synthetic method of aldehydes.
- Chikamatsu, Kiyofumi,Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro
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p. 1081 - 1084
(2007/10/02)
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