- Photoinduced Formation of Hybrid Aryl Pd-Radical Species Capable of 1,5-HAT: Selective Catalytic Oxidation of Silyl Ethers into Silyl Enol Ethers
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A direct visible light-induced generation of a hybrid aryl Pd-radical species from aryl iodide and Pd(0) is reported to enable an unprecedented (for hybrid Pd-radical species) hydrogen atom-transfer event. This approach allowed for efficient desaturation of readily available silyl ethers into synthetically valuable silyl enols. Moreover, this oxidation reaction proceeds at room temperature without the aid of exogenous photosensitizers or oxidants.
- Parasram, Marvin,Chuentragool, Padon,Sarkar, Dhruba,Gevorgyan, Vladimir
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- Molecular cloning and functional characterization of borneol dehydrogenase from the glandular trichomes of Lavandula x intermedia
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Several varieties of Lavandula x intermedia (lavandins) are cultivated for their essential oils (EOs) for use in cosmetic, hygiene and personal care products. These EOs are mainly constituted of monoterpenes including camphor, which contributes an off odor reducing the olfactory appeal of the oil. We have recently constructed a cDNA library from the glandular trichomes (the sites of EO synthesis) of L. x intermedia plants. Here, we describe the cloning of a borneol dehydrogenase cDNA (LiBDH) from this library. The 780 bp open reading frame of the cDNA encoded a 259 amino acid short chain alcohol dehydrogenase with a predicted molecular mass of ca. 27.5 kDa. The recombinant LiBDH was expressed in Escherichia coli, purified by Ni-NTA agarose affinity chromatography, and functionally characterized in vitro. The bacterially produced enzyme specifically converted borneol to camphor as the only product with Km and kcat values of 53 μM and 4.0 × 10-4 s-1, respectively. The LiBDH transcripts were specifically expressed in glandular trichomes of mature flowers indicating that like other Lavandula monoterpene synthases the expression of this gene is regulated in a tissue-specific manner. The cloning of LiBDH has far reaching implications in improving the quality of Lavandula EOs through metabolic engineering.
- Sarker, Lukman S.,Galata, Mariana,Demissie, Zerihun A.,Mahmoud, Soheil S.
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- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
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supporting information
p. 14701 - 14706
(2021/05/13)
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- A Structural View on the Stereospecificity of Plant Borneol-Type Dehydrogenases
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The development of sustainable processes for the valorization of byproducts and other waste streams remains an ongoing challenge in the field of catalysis. Racemic borneol, isoborneol and camphor are currently produced from α-pinene, a side product from the production of cellulose. The pure enantiomers of these monoterpenoids have numerous applications in cosmetics and act as reagents for asymmetric synthesis, making an enzymatic route for their separation into optically pure enantiomers a desirable goal. Known short-chain borneol-type dehydrogenases (BDHs) from plants and bacteria lack the required specificity, stability or activity for industrial utilization. Prompted by reports on the presence of pure (?)-borneol and (?)-camphor in essential oils from rosemary, we set out to investigate dehydrogenases from the genus Salvia and discovered a dehydrogenase with high specificity (E>120) and high specific activity (>0.02 U mg?1) for borneol and isoborneol. Compared to other specific dehydrogenases, the one reported here shows remarkably higher stability, which was exploited to obtain the first three-dimensional structure of an enantiospecific borneol-type short-chain dehydrogenase. This, together with docking studies, led to the identification of a hydrophobic pocket in the enzyme that plays a crucial role in the stereo discrimination of bornane-type monoterpenoids. The kinetic resolution of borneol and isoborneol can be easily integrated into the existing synthetic route from α-pinene to camphor thereby allowing the facile synthesis of optically pure monoterpenols from an abundant renewable source.
- Chánique, Andrea M.,Dimos, Nicole,Drienovská, Ivana,Calderini, Elia,Pantín, Mónica P.,Helmer, Carl P. O.,Hofer, Michael,Sieber, Volker,Parra, Loreto P.,Loll, Bernhard,Kourist, Robert
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p. 2262 - 2277
(2021/03/16)
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- Ruthenium-on-Carbon-Catalyzed Facile Solvent-Free Oxidation of Alcohols: Efficient Progress under Solid-Solid (Liquid)-Gas Conditions
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A protocol for the ruthenium-on-carbon (Ru/C)-catalyzed solvent-free oxidation of alcohols, which proceeds efficiently under solid-solid (liquid)-gas conditions, was developed. Various primary and secondary alcohols were transformed to corresponding aldehydes and ketones in moderate to excellent isolated yields by simply stirring in the presence of 10% Ru/C under air or oxygen conditions. The solvent-free oxidation reactions proceeded efficiently regardless of the solid or liquid state of the substrates and reagents and could be applied to gram-scale synthesis without loss of the reaction efficiency. Furthermore, the catalytic activity of Ru/C was maintained after five reuse cycles.
- Park, Kwihwan,Jiang, Jing,Yamada, Tsuyoshi,Sajiki, Hironao
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p. 1200 - 1205
(2021/12/29)
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- IBX-TfOH mediated oxidation of alcohols to aldehydes and ketones under mild reaction conditions
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An efficient, practical and facile procedure has been developed for the oxidation of primary and secondary alcohols using IBX-TfOH catalytic system in 1,4-dioxane at ambient temperature. The reaction affords quantitative yields of the corresponding carbonyl compounds without the formation of over oxidized products. The present synthetic protocol is compatible with a variety of substrates having arene, heteroarene and alkene functionalities. The developed synthetic protocol can be used for higher scale reactions as evident by the oxidation of alcohol at 1 g scale in higher yields by a simple filtration process.
- Kumar, Kamlesh,Kumar, Prashant,Joshi, Penny,Rawat, Diwan S
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supporting information
(2020/03/04)
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- Molecular cloning and functional characterization of a two highly stereoselective borneol dehydrogenases from Salvia officinalis L
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Enzymes for selective terpene functionalization are of particular importance for industrial applications. Pure enantiomers of borneol and isoborneol are fragrant constituents of several essential oils and find frequent application in cosmetics and therapy. Racemic borneol can be easily obtained from racemic camphor, which in turn is readily available from industrial side-streams. Enantioselective biocatalysts for the selective conversion of borneol and isoborneol stereoisomers would be therefore highly desirable for their catalytic separation under mild reaction conditions. Although several borneol dehydrogenases from plants and bacteria have been reported, none show sufficient stereoselectivity. Despite Croteau et al. describing sage leaves to specifically oxidize one borneol enantiomer in the late 70s, no specific enzymes have been characterized. We expected that one or several alcohol dehydrogenases encoded in the recently elucidated genome of Salvia officinalis L. would, therefore, be stereoselective. This study thus reports the recombinant expression in E. coli and characterization of two enantiospecific enzymes from the Salvia officinalis L. genome, SoBDH1 and SoBDH2, and their comparison to other known ADHs. Both enzymes produce preferentially (+)-camphor from racemic borneol, but (?)-camphor from racemic isoborneol.
- Drienovská, Ivana,Kolanovi?, Dajana,Chánique, Andrea,Sieber, Volker,Hofer, Michael,Kourist, Robert
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- Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts
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It is shown how secondary alcohols are oxidized to provide the corresponding ketones by use of Oxone and solid-supported hypervalent iodine catalysts. Under experimentally simple conditions with acetonitrile at elevated temperatures, excellent conversions were achieved with low catalyst loadings (0.2-5 mol%) when employing the conjugates 5 and 6 derived from IBX and IBS. The catalysts are broadly applicable to a range of alcohol substrates. Of primary importance with respect to sustainability issues, the metal-free catalysts are easily removed from the reaction mixture through filtration, and they can be re-used in oxidation processes for multiple times, without loss of catalytic activity.
- Ballaschk, Frederic,Kirsch, Stefan F.
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supporting information
p. 5896 - 5903
(2019/11/11)
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- Highly Efficient Abnormal NHC Ruthenium Catalyst for Oppenauer-Type Oxidation and Transfer Hydrogenation Reactions
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The ruthenium complex [Ru(OAc)(a-PC)2]Br (3) containing two abnormal NHC ligands is obtained by reaction of Ru(OAc)2(PPh3)2 (1) with 1-(2-diphenylphosphinoethyl)-3-mesitylimidazolium bromide in the presence of NaOAc. Complex 3 catalyzes the Oppenauer-type oxidation of a number of alcohols at unrivalled reaction rates reaching TOFs up to 550 000 h-1, at low catalyst loadings (S/C higher than 10 000) and using acetone in stoichiometric amounts. Complex 3 is also highly active in the reverse transfer hydrogenation of several ketones with 2-propanol, displaying TOFs up to 600 000 h-1
- Pardatscher, Lorenz,Hofmann, Benjamin J.,Fischer, Pauline J.,H?lzl, Sebastian M.,Reich, Robert M.,Kühn, Fritz E.,Baratta, Walter
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p. 11302 - 11306
(2019/11/21)
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- Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source
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The general dehalogenation of alkyl halides with zinc using D2O or H2O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.
- Xia, Aiyou,Xie, Xin,Hu, Xiaoping,Xu, Wei,Liu, Yuanhong
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p. 13841 - 13857
(2019/10/17)
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- Temperature Controls Guest Uptake and Release from Zn4L4 Tetrahedra
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We report the preparation of triazatruxene-faced tetrahedral cage 1, which exhibits two diastereomeric configurations (T1 and T2) that differ in the handedness of the ligand faces relative to that of the octahedrally coordinated metal centers. At lower temperatures, T1 is favored, whereas T2 predominates at higher temperatures. Host-guest studies show that T1 binds small aliphatic guests, whereas T2 binds larger aromatic molecules, with these changes in binding preference resulting from differences in cavity size and degree of enclosure. Thus, by a change in temperature the cage system can be triggered to eject one bound guest and take up another.
- Zhang, Dawei,Ronson, Tanya K.,Güryel, Songül,Thoburn, John D.,Wales, David J.,Nitschke, Jonathan R.
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supporting information
p. 14534 - 14538
(2019/10/11)
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- Practical Aerobic Oxidation of Alcohols: A Ligand-Enhanced 2,2,6,6-Tetramethylpiperidine-1-oxy/Manganese Nitrate Catalyst System
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A highly efficient, ligand-enhanced 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO)/Mn(NO3)2 catalyst system for the aerobic oxidation of alcohols is described. From the series of coordinating ligands studied herein, 2-picolinic acid (PyCOOH) improves the catalytic activity of TEMPO/Mn(NO3)2 remarkably. Under ambient air at room temperature in acetic acid, the ligand-enhanced catalyst converts aliphatic and benzylic primary alcohols that bear various functional groups into their respective aldehydes with near quantitative conversions. The applicability of the catalyst for convenient preparative synthesis was demonstrated by conducting oxidations on a gram scale. A change of TEMPO to the sterically less demanding 9-azabicyclo[3.3.1]nonane N-oxyl results in a Mn catalyst that is also able to oxidize secondary alcohols to ketones. Mechanistic studies showed that alcohols are oxidized by the oxoammonium cation derived from the nitroxyl radical. The active oxidant is regenerated by Mn(NO3)2, and this process is greatly promoted by the coordination of PyCOOH to Mn.
- Lagerblom, Kalle,Lagerspets, Emi,Keskiv?li, Juha,Cook, Chris,Ekholm, Filip,Parviainen, Arno,Repo, Timo
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p. 3880 - 3887
(2017/09/28)
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- Secondary Phosphine Oxides as Multitalented Preligands En Route to the Chemoselective Palladium-Catalyzed Oxidation of Alcohols
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Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd-catalyzed oxidation of alcohols by a hydrogen-abstracting methodology. SPOs were found to promote the hydrogen-abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H?Pd species. The catalytic system operates under neutral conditions and was proven to be compatible with various electrophilic and nucleophilic functionalities within the substrates as well as water- and air-sensitive functional groups.
- Vasseur, Alexandre,Membrat, Romain,Gatineau, David,Tenaglia, Alphonse,Nuel, Didier,Giordano, Laurent
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p. 728 - 732
(2017/03/13)
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- Copper(II) and cobalt(II) tetrazole-saccharinate complexes as effective catalysts for oxidation of secondary alcohols
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Mononuclear Cu(II) and Co(II) complexes comprising 2-methyltetrazole-saccharinate bidentate N,N-chelating ligand have been synthesized for the first time and tested as homogeneous catalysts for oxidation of secondary alcohols in a solvent-free and microwave assisted protocol using aqueous tert-butyl hydroperoxide (TBHP) as oxidant. The developed catalytic system exhibits broad functional group compatibility, allowing efficient and selective conversion of a variety of secondary alcohols, including allylic ones, into the corresponding ketones. With typical 0.2 mol% content of the catalyst and under 20–50 W microwave irradiation, most reactions are complete within 10 min, presenting TONs up to 5.5 × 102 and TOFs up to 1.1 × 104 h?1. No additives and co-oxidants have been used, while TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl) acts as inhibitor in most cases. A plausible reaction mechanism involving the new catalytic systems is outlined.
- Frija, Luís M.T.,Alegria, Elisabete C.B.A.,Sutradhar, Manas,Cristiano, M. Lurdes S.,Ismael, Amin,Kopylovich, Maximilian N.,Pombeiro, Armando J.L.
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p. 283 - 290
(2016/11/04)
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- Ultrasmall Platinum Nanoparticles Supported Inside the Nanospaces of Periodic Mesoporous Organosilica with an Imidazolium Network: An Efficient Catalyst for the Aerobic Oxidation of Unactivated Alcohols in Water
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The imidazolium group inside the wall of a periodic mesoporous organosilica provides an excellent environment for the stabilization of ultrasmall Pt nanoparticles ((NP)@PMO-IL) with significant activity and recyclability in the selective aerobic oxidation of various alcohols in water at ambient pressure of oxygen. In particular, the catalyst exhibited high activity in the oxidation of unactivated primary alcohols and sterically encumbered secondary aliphatic alcohols, which remain challenging substrates for many catalytic aerobic protocols.
- Karimi, Babak,Naderi, Zahra,Khorasani, Mojtaba,Mirzaei, Hamid M.,Vali, Hojatollah
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p. 906 - 910
(2016/03/15)
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- Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere
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We report a new Fe(NO3)3·9H2O/9-azabicyclo[3.3.1]nonan-N-oxyl catalyst system that enables efficient aerobic oxidation of a broad range of primary and secondary alcohols to the corresponding aldehydes and ketones at room temperature with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliphatic alcohol oxidation. This procedure can also be scaled up. Kinetic analysis demonstrates that C-H bond cleavage is the rate-determining step and that cationic species are involved in the reaction.
- Wang, Lianyue,Shang, SenSen,Li, Guosong,Ren, Lanhui,Lv, Ying,Gao, Shuang
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p. 2189 - 2193
(2016/03/15)
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- Iron-Catalysed Selective Aerobic Oxidation of Alcohols to Carbonyl and Carboxylic Compounds
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A method for aerobic alcohol oxidation catalysed by Fe(NO3)3/2,2’-bipyridine/TEMPO has allowed highly selective conversion of primary alcohols into either aldehydes or carboxylic acids in one-step. The oxidation of primary alcohols proceeded selectively to aldehydes, as TEMPO was present in the reaction. Nevertheless, the aldehydes were further oxidized into carboxylic acids as the reaction time was extended. Detailed investigation of the reaction suggested, that the deoxygenation of TEMPO into TMP enabled the auto-oxidation of aldehydes to carboxylic acids, which was initially inhibited in the presence of TEMPO. The procedure was also efficient in oxidation of secondary alcohols when TEMPO was replaced by the less sterically hindered ABNO.
- Lagerblom, Kalle,Wrigstedt, Pauli,Keskiv?li, Juha,Parviainen, Arno,Repo, Timo
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p. 1160 - 1165
(2016/11/23)
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- Isoborneol-dehydrogenated camphor refining method and equipment therefor
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The invention relates to an isoborneol-dehydrogenated camphor refining method. The method sequentially comprises a dehydrogenation reaction and solvent recovery step, a camphor vaporization subliming step and a camphor sublimation collecting step, wherein the dehydrogenation reaction and solvent recovery step comprises the steps of feeding a mixed solution of the isoborneol and an isoborneol dissolving solvent and a dehydrogenation catalyst into a reactor, heating the reactor so as to realize dehydrogenation reaction, exhausting hydrogen gas produced from the dehydrogenation reaction by using a fractionating column, and recovering the isoborneol dissolving solvent. According to the method, the disadvantage in the existing isoborneol-dehydrogenated camphor refining process that the steps of dehydrogenation reaction, solvent recovery and vaporization subliming are required to be carried out sequentially in different devices is overcome, the integration of a dehydrogenation reactor, a solvent recovery device and a sublimation device can be realized, and thus the steps of dehydrogenation reaction, solvent recovery and vaporization subliming can be carried out in the same reactor; and the method has the advantages of reducing working procedures and greatly reducing manpower and equipment costs.
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Paragraph 0052-0053
(2017/01/23)
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- Sonocatalytic degradation of a textile dye over Gd-doped ZnO nanoparticles synthesized through sonochemical process
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The present study was performed to sonochemically synthesize GdxZn1-xO (x = 0-0.1) nanoparticles for sonocatalysis of Acid Orange 7 (AO7) in an aqueous medium. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM
- Khataee, Alireza,Soltani, Reza Darvishi Cheshmeh,Karimi, Atefeh,Joo, Sang Woo
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p. 219 - 230
(2015/02/19)
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- Ruthenium Trichloride Catalyzed Highly Efficient Deoximation of Oximes to the Carbonyl Compounds and Nitriles without Acceptors
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An acceptor-free catalysis protocol for the deoximation of ketoximes and aldoximes using RuCl3 as the catalyst has been developed. Under the optimized conditions, various oximes were converted to ketones and nitriles with excellent isolated yields. An acceptor-free catalysis protocol for the deoximation of ketoximes and aldoximes using RuCl3 as the catalyst has been developed. Under the optimized conditions, various oximes were converted to ketones and nitriles with excellent isolated yields.
- Liu, Yuxiao,Yang, Na,Chu, Changhu,Liu, Renhua
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supporting information
p. 1011 - 1014
(2015/09/28)
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- Visible light photooxidation of nitrate: The dawn of a nocturnal radical
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Highly oxidizing nitrate radicals (NO3?) are easily accessed from readily available nitrate salts by visible light photoredox catalysis using a purely organic dye as the catalyst and oxygen as the terminal oxidant. The interaction of the excited catalyst and nitrate anions was studied by spectroscopic methods to elucidate the mechanism, and the method was applied to the NO3? induced oxidation of alkynes and alcohols.
- Hering,Slanina,Hancock,Wille,K?nig
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supporting information
p. 6568 - 6571
(2015/04/14)
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- Substrate flexibility and reaction specificity of tropinone reductase-like short-chain dehydrogenases
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Annotations of protein or gene sequences from large scale sequencing projects are based on protein size, characteristic binding motifs, and conserved catalytic amino acids, but biochemical functions are often uncertain. In the large family of short-chain dehydrogenases/reductases (SDRs), functional predictions often fail. Putative tropinone reductases, named tropinone reductase-like (TRL), are SDRs annotated in many genomes of organisms that do not contain tropane alkaloids. SDRs in vitro often accept several substrates complicating functional assignments. Cochlearia officinalis, a Brassicaceae, contains tropane alkaloids, in contrast to the closely related Arabidopsis thaliana. TRLs from Arabidopsis and the tropinone reductase isolated from Cochlearia (CoTR) were investigated for their catalytic capacity. In contrast to CoTR, none of the Arabidopsis TRLs reduced tropinone in vitro. NAD(H) and NADP(H) preferences were relaxed in two TRLs, and protein homology models revealed flexibility of amino acid residues in the active site allowing binding of both cofactors. TRLs reduced various carbonyl compounds, among them terpene ketones. The reduction was stereospecific for most of TRLs investigated, and the corresponding terpene alcohol oxidation was stereoselective. Carbonyl compounds that were identified to serve as substrates were applied for modeling pharmacophores of each TRL. A database of commercially available compounds was screened using the pharmacophores. Compounds identified as potential substrates were confirmed by turnover in vitro. Thus pharmacophores may contribute to better predictability of biochemical functions of SDR enzymes.
- Reinhardt, Nicole,Fischer, Juliane,Coppi, Ralph,Blum, Elke,Brandt, Wolfgang,Draeger, Birgit
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- Organocatalytic oxidation of secondary alcohols using 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA)
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Diamine, 1,2-di(1-naphthyl)-1,2-ethanediamine (NEDA), efficiently catalyzes the oxidation of alcohols by using TBHP as an oxidant. Notably, secondary benzyl alcohols are oxidized in almost quantitative yields, and the catalyst also displays high activity towards even hindered cycloaliphatic secondary alcohols. With enantiopure (R,R)-NEDA, oxidative kinetic resolution can be realized and depending on the alcohol ee up to 99% are achieved.
- Al-Hunaiti, Afnan,R?is?nen, Minna,Pihko, Petri,Leskel?, Markku,Repo, Timo
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supporting information
p. 6141 - 6144
(2015/03/30)
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- 4-Benzamido-TEMPO catalyzed oxidation of a broad range of alcohols to the carbonyl compounds with NaBrO3 under mild conditions
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4-Benzamido-TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO3 under room temperature conditions has been developed. The credible, operationally convenient and economical, and condition mild oxidation protocol is particularly of interest in laboratory and in fine chemicals manufacture. 4-Benzamido-TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO3 as oxidant under room temperature conditions has been developed. Copyright
- Shen, Jiaxuan,Sun, Jiangkai,Qin, Shuangshuang,Chu, Changhu,Liu, Renhua
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p. 405 - 409
(2014/06/10)
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- Selective oxidation of alcohols with alkali metal bromides as bromide catalysts: Experimental study of the reaction mechanism
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A bromide-catalyzed oxidation of alcohols was developed which proceeded in the presence of an alkali metal bromide and an oxidant under mild conditions. The reaction involved an organic-molecule-free oxidation using KBr and Oxone and a Br?nsted acid assisted oxidation using KBr and aqueous H 2O2 solution to provide a broad range of carbonyl compounds in high yields. Moreover, the bromide-catalyzed oxidation of primary alcohols enabled the divergent synthesis of carboxylic acids and aldehydes under both reaction conditions in the presence of TEMPO. A possible catalytic mechanism was suggested on the basis of various mechanistic studies.
- Moriyama, Katsuhiko,Takemura, Misato,Togo, Hideo
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p. 6094 - 6104
(2014/07/21)
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- Oxidation of alcohols to aldehydes or ketones with 1-acetoxy-1,2- benziodoxole-3(1H)-one derivatives
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Various benzylic and aliphatic alcohols were smoothly oxidized to the corresponding aromatic aldehydes and ketones as well as aliphatic ketones by treatment with 1-acetoxy-5-nitro-1,2-benziodoxole-3(1H)-one (ANBX), 1-acetoxy-5-bromo-1,2-benziodoxole-3(1H)-one (ABBX), 1-acetoxy-5-chloro-1,2- benziodoxole-3(1H)-one (ACBX), and 1-acetoxy-5-fluoro-1,2-benziodoxole-3(1H)-one (AFBX). These new tri-valent iodine compounds were prepared from 5-substituted 2-iodobenzoic acids and meta-chloroperoxybenzoic acid (m-CPBA). ANBX and ABBX were the most effective reagents for this oxidation of alcohols, and this present reaction is very attractive because of the ease of product isolation and the reusability of the reagents.
- Iinuma, Masataka,Moriyama, Katsuhiko,Togo, Hideo
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p. 772 - 780
(2014/03/21)
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- Highly efficient Cu(I)-catalyzed oxidation of alcohols to ketones and aldehydes with diaziridinone
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A novel and efficient Cu(I)-catalyzed oxidation of alcohols has been achieved with di-tert-butyldiaziridinone as the oxidant under mild conditions. A wide variety of primary and secondary alcohols with various functional groups can be oxidized to aldehydes and ketones in high yields. The reaction proceeds under neutral conditions making it compatible with acid- or base-sensitive substrates, and it is amenable to gram scale.
- Zhu, Yingguang,Zhao, Baoguo,Shi, Yian
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supporting information
p. 992 - 995
(2013/04/10)
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- Efficient aerobic oxidation of secondary alcohols at ambient temperature with an ABNO/NOx catalyst system
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New highly practical methods are presented for aerobic oxidation of secondary alcohols with a nitroxyl radical in combination with HNO3, NaNO2, or both as cocatalysts. Diverse nitroxyls are compared, including several novel bicyclic derivatives. Catalyst systems with the readily available nitroxyls, 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) and 9-azabicyclo[3.3.1]nonan-3-one-N-oxyl (keto-ABNO), are optimized in acetic acid or acetonitrile as the solvent. The reactions are compatible with substrates bearing diverse functional groups and proceed efficiently under mild conditions at ambient pressure and temperature.
- Lauber, Markus B.,Stahl, Shannon S.
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p. 2612 - 2616
(2013/11/19)
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- Oxidation of alcohols to aldehydes and ketones by HIO3 in presence of NaHSO4·H2O
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Different types of alcohols are efficiently converted to their corresponding aldehyds and ketones with HIO3 in presence of NaHSO4·H2O. All reaction was performed in CH 3CN medium in good to high yields.
- Khademian, Mohsen,Khademian, Maryam,Rahimnejad, Mostafa,Mokhtarian, Nader
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p. 2927 - 2928
(2013/04/24)
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- A convenient and selective palladium-catalyzed aerobic oxidation of alcohols
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An efficient procedure for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with molecular oxygen under ambient conditions has been achieved. By applying catalytic amounts of Pd(OAc) 2 in the presence of tertiary phosphine oxides (O=PR3) as ligands, a variety of substrates are selectively oxidized without formation of ester byproducts. Spectroscopic investigations and DFT calculations suggest stabilization of the active palladium(II) catalyst by phosphine oxide ligands.
- Gowrisankar, Saravanan,Neumann, Helfried,Goerdes, Dirk,Thurow, Kerstin,Jiao, Haijun,Beller, Matthias
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supporting information
p. 15979 - 15984
(2014/04/03)
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- Synthesis and characterization of alkyl-imidazolium-based periodic mesoporous organosilicas: A versatile host for the immobilization of perruthenate (RuO4-) in the aerobic oxidation of alcohols
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The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3- trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10 % imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols.
- Karimi, Babak,Elhamifar, Dawood,Yari, Omolbanin,Khorasani, Mojtaba,Vali, Hojatollah,Clark, James H.,Hunt, Andrew J.
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p. 13520 - 13530
(2012/11/07)
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- A novel approach towards dethioacetalization reactions with H 2O2-SOCl2 system
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A simple and efficient protocol for the deprotection of dithioacetal, 1,3-dithianes and 1,3-dithiolanes has been developed using H2O 2-SOCl2 reagent system. In addition to the absence of overoxidation products for oxidation-prone substrates, high chemoselectivity, the low cost and availability of the reagents, simplicity of the method, short reaction times, and excellent yields can also be considered as strong points for this method.
- Bahrami, Kiumars,Khodaei, Mohammad Mehdi,Tajik, Maryam,Shakibaian, Vida
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experimental part
p. 81 - 85
(2012/03/26)
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- Grafting of oxo-vanadium Schiff base on graphene nanosheets and its catalytic activity for the oxidation of alcohols
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Graphene oxide was found to be a convenient and efficient supporting material for grafting of oxo-vanadium Schiff base via covalent attachment. The low dimensionality and rich surface chemistry of graphene oxide play critical roles in order to achieve a good degree of such grafting. Catalytic potential of the so prepared graphene-bound oxo-vanadium Schiff base and comparison with its homogeneous analogue was studied for the oxidation of various alcohols to carbonyl compounds using tert-butylhydroperoxide as oxidant. The structural and chemical nature of the catalyst was characterized by a variety of techniques including XRD, FTIR, TGA, TEM, and ICP-AES. The immobilized complex was found to be highly efficient and showed comparable catalytic reactivity as its homogenous analogue with the added benefits of facile recovery and recycling of the heterogeneous catalyst. The graphene-bound oxo-vanadium Schiff base was successfully reused for several runs without significant loss in its catalytic activity. The Royal Society of Chemistry 2012.
- Mungse, Harshal P.,Verma, Sanny,Kumar, Neeraj,Sain, Bir,Khatri, Om P.
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experimental part
p. 5427 - 5433
(2012/06/15)
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- Highly efficient, organocatalytic aerobic alcohol oxidation
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5-Fluoro-2-azaadamantane N-oxyl (5-F-AZADO) realizes a simple, organocatalytic aerobic alcohol oxidation system that has a wide scope under mild conditions at ambient pressure and temperature and is weakly acidic and halogen- and transition-metal-free. The oxoammonium nitrate (5-F-AZADO +NO3-) works as a bifunctional catalyst of 5-F-AZADO and NOx that enables the catalytic aerobic oxidation of alcohols by itself (a metal-salt-free system).
- Shibuya, Masatoshi,Osada, Yuji,Sasano, Yusuke,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 6497 - 6500
(2011/06/23)
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- Aqueous hydrogen peroxide and 2,4,4,6-tetrabromo-2,5-cyclohexadienone catalyst: An efficient mild ecofriendly cleaving reagent of thioacetals and thioketals
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A clean mild efficient dethioacetalization protocol is revealed utilizing a catalytic combination of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) (20 mol%) with 30% hydrogen peroxide as a terminal oxidizer in aqueous acetonitrile at room temperature. High yields of carbonyl compounds without overoxidation for oxidation-prone aromatic and furyl aldehydes, simple work-up, use of cost-compatible readily accessible reagents, tolerance of a wide range of common functional and protecting groups including phenolic hydroxy, methylenedioxy, acetoxy, aromatic amino, carbon-carbon double bond, allyl, benzyl, TBDPS ethers, NHBoc, NHBz are the key attractive features of the method.
- Ganguly, Nemai C.,Nayek, Subhasis,Barik, Sujoy Kumar
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scheme or table
p. 251 - 256
(2012/03/11)
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- One-Pot Bi(OTf)catalyzed oxidative deprotection of tert -butyldimethyl silyl ethers with TEMPO and co-oxidants
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A sequential one-pot synthesis for the oxidation of primary and secondary tert-butyldimethylsilyl (TBDMS) ethers, using catalytic amounts of metal triflates and TEMPO in combination with PhIO or PhI(OAc)in THF or acetonitrile, is described. Acid-sensitive protecting groups such as methylidene, isopropylidene, acetals, and Boc are unaffected under the reaction conditions. Another feature of this procedure is its high selectivity for TBDMS ethers over tert-butyldiphenylsilyl ethers and of aliphatic TBDMS groups over phenolic TBDMS groups. Georg Thieme Verlag Stuttgart - New York.
- Barnych, Bogdan,Vatèle, Jean-Michel
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experimental part
p. 2048 - 2052
(2011/10/19)
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- A chromium-free synthesis of enantiopure 5-oxoborneol
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Enantiopure (-)-5-oxoborneol was obtained in 35% overall yield in two steps, starting from readily available (-)-bornyl acetate and using oxone as a safe and inexpensive oxidant. The reported procedure avoids the use of large excess of noxious chromium(VI), which was required by the so far reported syntheses.
- Tartaggia, Stefano,Padovan, Pierluigi,Borsato, Giuseppe,De Lucchi, Ottorino,Fabris, Fabrizio
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scheme or table
p. 4478 - 4480
(2011/09/19)
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- Reactivity of endo-3-bromocamphor with sulfur-centered nucleophiles by an electron transfer mechanism. Electrophilic behaviour of the 3-camphoryl radical
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The photostimulated reaction of arylthiolate ions with endo-3-bromocamphor produced both reduction and substitution products. The pKa and proton affinities of the conjugated acids were found to be good indicators of the reactivity.
- Uranga, Jorge G.,Santiago, Ana N.
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experimental part
p. 2969 - 2974
(2011/05/08)
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- Novel organic-inorganic hybrid mesoporous silica supported oxo-vanadium schiff base for selective oxidation of alcohols
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Novel organic-inorganic hybrid mesoporous materials containing diimine moieties inside the pore wall were used for the grafting of an oxo-vanadium Schiff base complex at the mesopore surface. The prepared catalyst was found to be highly active and selective for the oxidation of a variety of primary, secondary and α-hydroxy carbonyl compounds to the corresponding aldehydes, ketones and 1,2-dicarbonyl compounds using tert-butyl hydroperoxide as oxidant under mild reaction conditions. After completion of the reaction, the catalyst could easily be recovered by simple filtration and could be reused several times without significant change in the catalytic efficiency. Importantly, the catalyst did not show any leaching during the reaction, confirming that the prepared catalyst was truly heterogeneous in nature. Copyright
- Verma, Sanny,Nandi, Mahasweta,Modak, Arindam,Jain, Suman L.,Bhaumik, Asim
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experimental part
p. 1897 - 1902
(2011/10/04)
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- Simple preparation and application of TEMPO-coated Fe3O 4 superparamagnetic nanoparticles for selective oxidation of alcohols
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The organic oxidant TEMPO (2,2,4,4-tetramethylpiperdine-1-oxyl) was immobilized on iron oxide (Fe3O4) superparamagnetic nanoparticles by employing strong metal-oxide chelating phosphonates and azide/alkyne "click" chemistry. This simple preparation yields recyclable TEMPO-coated nanoparticles with good TEMPO loadings. They have excellent magnetic response and efficiently catalyze the oxidation of a wide range of primary and secondary alcohols to aldehydes, ketones, and lactones under either aerobic acidic MnII/CuII oxidizing Minisci conditions, or basic NaOCl Anelli conditions. The nanoparticles could be recycled more than 20 times under the Minisci conditions and up to eight times under the Anelli conditions with good to excellent substrate conversions and product selectivities. Immobilization of the catalyst through a phosphonate linkage allows the particles to withstand acidic oxidizing environments with minimal catalyst leaching. Clicking TEMPO to the phosphonate prior to phosphonate immobilization, rather than after, ensures the clicked catalyst is the only species on the particle surface. This facilitates quantification of the catalyst loading. The stability of the phosphonate linker and simplicity of this catalyst immobilization method make this an attractive approach for tethering catalysts to oxide supports, creating magnetically separable catalysts that can be used under neutral or acidic conditions. Recycling to a different TEMPO: An extremely simple and economic synthesis of a recyclable 2,2,4,4-tetramethylpiperdine-1-oxyl(TEMPO)-coated superparamagnetic catalyst is described. The catalyst shows excellent performance in the rapid oxidation of primary and secondary benzylic and aliphatic alcohols by using oxygen and MnII/CuII or biphasic NaOCl/KBr conditions.
- Tucker-Schwartz, Alexander K.,Garrell, Robin L.
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experimental part
p. 12718 - 12726
(2011/02/21)
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- H2O2-oxidation of alcohols promoted by polymeric phosphotungstate catalysts
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A novel polymeric phosphotungstate catalyst bearing a poly(ethylene oxide-pyridinium) matrix was developed that efficiently promoted oxidation of a variety of alcohols, including highly sterically demanding neopentyl alcohols, with hydrogen peroxide, to afford the corresponding carbonyl compounds in up to quantitative yield. The chemoselective oxidation of sterically hindered secondary alcohols in the presence of primary alcohols was achieved. The catalyst could be reused four times without any loss of catalytic activity.
- Yamada, Yoichi M.A.,Jin, Chung Keun,Uozumi, Yasuhiro
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supporting information; experimental part
p. 4540 - 4543
(2010/12/25)
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- A glandular trichome-specific monoterpene alcohol dehydrogenase from Artemisia annua
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The major components of the isoprenoid-rich essential oil of Artemisia annua L. accumulate in the subcuticular sac of glandular secretory trichomes. As part of an effort to understand isoprenoid biosynthesis in A. annua, an expressed sequence tag (EST) collection was investigated for evidence of genes encoding trichome-specific enzymes. This analysis established that a gene denoted Adh2, encodes an alcohol dehydrogenase and shows a high expression level in glandular trichomes relative to other tissues. The gene product, ADH2, has up to 61% amino acid identity to members of the short chain alcohol dehydrogenase/reductase (SDR) superfamily, including Forsythia × intermedia secoisolariciresinol dehydrogenase (49.8% identity). Through in vitro biochemical analysis, ADH2 was found to show a strong preference for monoterpenoid secondary alcohols including carveol, borneol and artemisia alcohol. These results indicate a role for ADH2 in monoterpenoid ketone biosynthesis in A. annua glandular trichomes.
- Polichuk, Devin R.,Zhang, Yansheng,Reed, Darwin W.,Schmidt, Janice F.,Covello, Patrick S.
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experimental part
p. 1264 - 1269
(2011/05/30)
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- Development of new recyclable reagents and catalytic systems based on hypervalent iodine compounds
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Recent advances in the development of polymer-supported iodine(V) oxidants, recyclable monomeric hypervalent iodine(III) reagents and catalytic systems based on hypervalent iodine compounds are discussed. These efficient and environmentally friendly reagents and catalysts are particularly useful for oxidative transformations of alcohols to carbonyl compounds and for oxidations at the benzylic position.
- Yusubov, Mekhman S.,Zhdankin, Viktor V.
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experimental part
p. 185 - 191
(2011/03/19)
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- 2-iodoxybenzenesulfonic acid as an extremely active catalyst for the selective oxidation of alcohols to aldehydes, ketones, carboxylic acids, and enones with oxone
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Electron-donating group-substituted 2-iodoxybenzoic acids (IBXs) such as5-Me-IBX (1g), 5-MeO-IBX (1h), and 4,5-Me2-IBX were superior to IBX 1a as catalysts for the oxidation of alcohols with Oxone (a trad emark of DuPont) under nonaqueous conditions, although Oxone was almost insoluble in most organic solvents. The catalytic oxidation proceeded more rapidly and cleanly in nitromethane. Furthermore, 2-iodoxybenzenesulfonic acid (IBS, 6a) was much more active than modified IBXs. Thus, we established a highly efficient and selective method for the oxidation of primary and secondary alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones with Oxone in nonaqueous nitromethane, acetonitrile, or ethyl acetate in the presence of 0.05-5molpercentof 6a, which was generated in situ from 2-iodobenzenesulfonic acid (7a) or its sodium salt. Cycloalkanones could be further oxidized to α,β- cycloalkenones or lactones by controlling the amounts of Oxone under the same conditions as above. When Oxone was used under nonaqueous conditions, Oxone wastes could be removed by simple filtration. Based on theoretical calculations, we considered that the relatively ionic character of the intramolecular hypervalent iodine-OSO2 bond of IBS might lower the twisting barrier of the alkoxyperiodinane intermediate 16.
- Uyanik, Muhammet,Akakura, Matsujiro,Ishihara, Kazuaki
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supporting information; experimental part
p. 251 - 262
(2009/06/28)
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- Ruthenium-functionalized nickel hydroxide catalyst for highly efficient alcohol oxidations in the presence of molecular oxygen
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Ru/Ni(OH)2 composite, prepared by simple wetness impregnation method, has demonstrated highly efficient alcohol oxidation reaction in the presence of molecular oxygen at T = 363 K with good selectivity (>99%) and excellent reaction yield (TOF ~ 132 h-1).
- Venkatesan,Senthil Kumar,Lee, Jyh-Fu,Chan, Ting-Shan,Zen, Jyh-Myng
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body text
p. 1912 - 1914
(2009/10/17)
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- Homogeneous, anaerobic (N-heterocyclic carbene)-Pd or -Ni catalyzed oxidation of secondary alcohols at mild temperatures
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The use of aryl chlorides as oxidants for the selective oxidation of a variety of secondary alcohols in anaerobic conditions with (NHC)-Pd and -Ni systems (NHC = N-heterocyclic carbene) at very mild temperatures is presented.
- Berini, Christophe,Brayton, Daniel F.,Mocka, Corey,Navarro, Oscar
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supporting information; experimental part
p. 4244 - 4247
(2009/12/31)
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- Oxidation of secondary terpene alcohols by chlorine dioxide
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Secondary terpene alcohols cis- and trans-verbenol, neo-iso-verbanol, borneol, iso-borneol, and menthol were oxidized by chlorine dioxide into the corresponding ketones. It was shown that the nature of the solvent and catalyst and the structure of the starting compound, including the stereochemistry of the hydroxyl, influenced the oxidation process.
- Frolova,Popov,Rubtsova,Kuchin
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experimental part
p. 724 - 727
(2009/05/09)
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- Aqueous hydrogen peroxide activated by ammonium heptamolybdate catalyst - A mild clean effective reagent system for the deprotection of oximes, semicarbazones and phenylhydrazones at room temperature
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Oximes, phenylhydrazones and semicarbazones of a wide variety of aldehydes and ketones are cleanly cleaved to the corresponding carbonyl compounds in good to acceptable yields using environmentally safe and convenient oxidizer, 30% hydrogen peroxide in catalytic combination with 20 mol% ammonium heptamolybdate in aqueous acetic acid or tetrahydrofuran at room temperature. Absence of overoxidized by-products in case of oxidation-prone aromatic aldehydes, α,β-unsaturated aldehydes and compatibility with various common functional groups such as hydroxy, methoxy, epoxy, amino, methylenedioxy, conjugated and unconjugated C=C bonds are some of the key advantageous features of the method.
- Ganguly, Nemai C.,Nayek, Subhasish,Barik, Sujoy Kumar,Dutta, Sanjoy
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body text
p. 711 - 716
(2009/12/05)
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- Green, transition-metal-free aerobic oxidation of alcohols using a highly durable supported organocatalyst
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(Chemical Equation Presented) Up-tempo catalysis: The nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) supported on the mesoporous material SBA-15 provides a highly stable and reusable catalyst (1) for the aerobic oxidation of primary, secondary, and highly hindered alcohols. The catalyst can be recovered and reused in at least another 14 reaction cycles.
- Karimi, Babak,Biglari, Abbass,Clark, James H.,Budarin, Vitaly
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p. 7210 - 7213
(2008/09/17)
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- A practical palladium catalyzed dehalogenation of aryl halides and α-haloketones
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A practical and high-yielding protocol for the dehalogenation of aromatic halides is presented. In the presence of palladium acetate, triphenylphosphine, and potassium carbonate, a number of highly functionalized aromatic halides as well as α-haloketones were dehalogenated with alcohols as hydrogen donors.
- Chen, Jingbo,Zhang, Yushun,Yang, Liquan,Zhang, Xiang,Liu, Jianping,Li, Liang,Zhang, Hongbin
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p. 4266 - 4270
(2007/10/03)
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