- A PALLADIUM CATALYZED CONVERSION OF HALOHYDRINS TO KETONES
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Pd(OAc)2 combined with P(o-Tol)3 catalyzes the conversion of halohydrins to ketones in the presence of K2CO3.Various halohydrins, which are easily available from olefins, can be converted to ketones in high yields.
- Tsuji, Jiro,Nagashima, Hideo,Sato, Koji
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- Metalloporphyrinic framework containing multiple pores for highly efficient and selective epoxidation
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Metalloporphyrin MnIIICl-5,10,15,20-tetrakis(3,5- biscarboxylphenyl)porphyrin, having eight carboxylate groups in multiple coordination modes, connects with paddle-wheel Zn2(COO)4 units for the construction of an interesting porous porphyrinic framework that demonstrates high efficiency and stability upon epoxidation of olefins with excellent substrate size selectivity.
- Yang, Xiu-Li,Wu, Chuan-De
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- Direct oxidative carboxylation of terminal olefins to cyclic carbonates by tungstate assisted-tandem catalysis
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Tungstate catalysts are well established for olefin epoxidation reactions, while their catalytic activity for CO2 insertion in epoxides is a more recent discovery. This dual reactivity of tungstate prompted the present development of a catalytic tandem process for the direct conversion of olefins into the corresponding cyclic organic carbonates (COCs). Each of the two steps was studied in the presence of the ammonium tungstate ionic liquid catalyst-[N8,8,8,1]2[WO4]-obtained via a benign procedure starting from ammonium methylcarbonate ionic liquids. The catalytic epoxidation first step was optimised on 1-decene as model substrate, using H2O2 as benign oxidant, [N8,8,8,1]2[WO4] as catalyst and phosphoric acid as promoter affording quantitative conversion with 92% selectivity towards decene oxide. Unfortunately, the addition of CO2 from the start (auto-tandem catalysis) gave low yields of decene carbonate (10%). On the contrary, the addition of 1 atm CO2 and tetrabutyl ammonium iodide after completion of the epoxidation first step without any intermediate work-up (assisted-tandem catalysis) afforded a 94% yield in decene carbonate. The protocol could be scaled up to a 10 gram scale. The scope of the reaction was demonstrated for primary aliphatic olefins with different alkyl chain lengths (C6-C16), while cyclic and aromatic activated olefins such as cyclohexene and styrene suffered from the formation of undesired overoxidation products in the first step.
- Calmanti, Roberto,Perosa, Alvise,Selva, Maurizio
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p. 7609 - 7619
(2021/10/12)
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- Preparation of flavin-containing mesoporous network polymers and their catalysis
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Riboflavin tetramethacrylate (RFlTMA) was prepared as a flavin monomer and copolymerized with ethylene glycol dimethacrylate (EGDMA) under polymerization-induced phase separation conditions. The resulting flavin-containing mesoporous network polymer, poly(RFlTMA-co-EGDMA), was found to be a more effective catalyst than riboflavin tetraacetate (RFlTA), a soluble analogue, for aerobic hydrogenation of olefins despite its heterogeneity, which allowed for its multiple recovery and reuse through simple filtrations and washings without loss in catalytic activity. In addition, the polymeric flavin was demonstrated to be utilized also as an effective photocatalyst in the oxidation of benzyl alcohols.
- Arakawa, Yukihiro,Sato, Fumiaki,Ariki, Kenta,Minagawa, Keiji,Imada, Yasushi
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supporting information
(2020/02/15)
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- Copper based coordination polymers based on metalloligands: Utilization as heterogeneous oxidation catalysts
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This work presents the synthesis and characterization of two Cu(ii)-based coordination polymers prepared by utilizing two different Co(iii)-based metalloligands offering appended arylcarboxylic acid groups. Both coordination polymers are three-dimensional in nature and present pores and channels filled with water molecules. Both coordination polymers function as heterogeneous catalysts for the epoxidation of various olefins using O2 while employing isobutyraldehyde as the coreductor and for peroxide-mediated oxidation of assorted benzyl alcohols. The catalytic results illustrate efficient oxidation reactions, whereas the hot-fltration test and leaching experiments indicate the true heterogeneous nature of the catalysis.
- Kumar, Gulshan,Hussain, Firasat,Gupta, Rajeev
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p. 16985 - 16994
(2019/01/03)
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- Mechanistically Driven Development of an Iron Catalyst for Selective Syn-Dihydroxylation of Alkenes with Aqueous Hydrogen Peroxide
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Product release is the rate-determining step in the arene syn-dihydroxylation reaction taking place at Rieske oxygenase enzymes and is regarded as a difficult problem to be resolved in the design of iron catalysts for olefin syn-dihydroxylation with potential utility in organic synthesis. Toward this end, in this work a novel catalyst bearing a sterically encumbered tetradentate ligand based in the tpa (tpa = tris(2-methylpyridyl)amine) scaffold, [FeII(CF3SO3)2(5-tips3tpa)], 1 has been designed. The steric demand of the ligand was envisioned as a key element to support a high catalytic activity by isolating the metal center, preventing bimolecular decomposition paths and facilitating product release. In synergistic combination with a Lewis acid that helps sequestering the product, 1 provides good to excellent yields of diol products (up to 97% isolated yield), in short reaction times under mild experimental conditions using a slight excess (1.5 equiv) of aqueous hydrogen peroxide, from the oxidation of a broad range of olefins. Predictable site selective syn-dihydroxylation of diolefins is shown. The encumbered nature of the ligand also provides a unique tool that has been used in combination with isotopic analysis to define the nature of the active species and the mechanism of activation of H2O2. Furthermore, 1 is shown to be a competent synthetic tool for preparing O-labeled diols using water as oxygen source.
- Borrell, Margarida,Costas, Miquel
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supporting information
p. 12821 - 12829
(2017/09/25)
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- Selective oxidation of hydrocarbons under air using recoverable silver ferrite-graphene (AgFeO2-G) nanocomposite: A good catalyst for green chemistry
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The selective oxidation of hydrocarbons is a main academic and industrial research challenge. A lot of researches have been done about this issue, but till now relatively little attention has been paid to graphene-complex oxide nanocomposites. Herein, we report our studies on a new catalyst. Silver ferrite-graphene (AgFeO2-G) as a separable nanocomposite from the reaction solution, was used as an effective oxidizing agent for the oxidation of various hydrocarbons (1- decene, cyclohexene, cis-cycloctene, cyclohexane, cyclooctane etc.) under mild conditions (55 °C, 8 h) with high conversion and selectivity using air, that is proper for 'green' chemistry. Metal or metal oxide nanoparticles assembled on graphene sheets revealed high electrocatalytic activity. Indeed, AgFeO2 with graphene due to low band gap and graphene oxide with large amounts of oxygen-containing groups, provide facility catalytic activity of catalyst-supported system. We also found that, with this catalyst, selective oxidation could be achieved without the need for the addition of solvent, which is appropriate in particular for 'green' chemistry. The catalysts showed little deactivation and maintained their conversion and selectivity levels duration of the measurements.
- Hosseini, Seyed Majid,Hosseini-Monfared, Hassan,Abbasi, Vahideh,Khoshroo, Mohammad Reza
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- Solvent-Free Aerobic Epoxidation of Dec-1-ene Using Gold/Graphite as a Catalyst
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The oxidation of dec-1-ene has been investigated using gold nanoparticles supported on graphite in the presence of a radical initiator (α,α-azobisisobutyronitrile) using oxygen from air as oxidant. We have investigated the influence of the reaction temperature (70-100 °C), catalyst mass and reaction time on the epoxide yield. In the absence of a radical initiator the reaction does not proceed, although auto-oxidation can occur at higher temperatures in the range studied. However, in the presence of an initiator, selective oxidation occurs and the initiator propagates the reaction through the formation of a peroxy-radical at the allylic C3 position. Graphite enhances the formation of the allylic products dec-1-en-3-ol, dec-1-en-3-one, and dec-2-en-1-ol; however, the addition of gold nanoparticles to the graphite, enhances formation of 1,2-epoxydecane. It is suggested that gold suppresses the formation of allylic products via a Russell termination. Graphical Abstract: [Figure not available: see fulltext.]
- Gupta, Upendra Nath,Dummer, Nicholas F.,Pattisson, Samuel,Jenkins, Robert L.,Knight, David W.,Bethell, Donald,Hutchings, Graham J.
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p. 689 - 696
(2015/08/04)
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- Development of chelate resin-supported palladium catalysts for chemoselective hydrogenation
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Abstract Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palladium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate. Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydrogenation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least 5 runs.
- Monguchi, Yasunari,Ichikawa, Tomohiro,Nozaki, Kei,Kihara, Kensuke,Yamada, Yuuko,Miyake, Yutaka,Sawama, Yoshinari,Sajiki, Hironao
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supporting information
p. 6499 - 6505
(2015/08/18)
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- Unique Chemoselective Hydrogenation using a Palladium Catalyst Immobilized on Ceramic
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A heterogeneous palladium catalyst supported on a ceramic (5 % Pd/ceramic) was developed. The catalyst exhibited a specific chemoselectivity for hydrogenation that has never been achieved by other palladium-catalyzed methods. Either aliphatic or aromatic N-Cbz groups could be deprotected to the corresponding free-amines, while the hydrogenolysis of benzyl esters and ethers did not proceed. Furthermore, aryl chlorides and epoxides were tolerant under the Pd/ceramic-catalyzed hydrogenation conditions. 5 % Pd/ceramic could be reused without any loss of catalyst activity, as no palladium leaching was detected in the reaction media.
- Monguchi, Yasunari,Marumoto, Takahisa,Ichikawa, Tomohiro,Miyake, Yutaka,Nagae, Yoshiyuki,Yoshida, Michiyuki,Oumi, Yasunori,Sawama, Yoshinari,Sajiki, Hironao
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p. 2155 - 2160
(2015/11/24)
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- Co6(μ3-OH)6 cluster based coordination polymer as an effective heterogeneous catalyst for aerobic epoxidation of alkenes
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A new hexaprismane Co(ii)6(μ3-OH)6 cluster-based three-dimensional coordination polymer ({Co(μ3-OH) (HCOO)0.72(CH3COO)0.28}n, Co6-CP) was successfully synthesized and characterized with single-crystal XRD, IR spectra, TGA spectra and elemental analysis. Co6-CP was used as an effective heterogeneous catalyst for the aerobic epoxidation of various alkenes. For the catalytic epoxidation of trans-stilbene, the conversion and selectivity towards the epoxide reached 98.6 and 98.0%, respectively. Also, an average TOF of 22 h-1 was obtained for the reaction. The results indicated that Co6-CP displayed excellent aerobic epoxidation activity among the reported coordination polymer materials, even rivaling the traditional heterogeneous cobalt catalysts. The influence of the reaction parameters such as temperature and oxygen flow rate for the epoxidation of the trans-stilbene were also studied in detail.
- Gao, Junkuo,Bai, Linlu,Zhang, Qian,Li, Yongxin,Rakesh, Ganguly,Lee, Jong-Min,Yang, Yanhui,Zhang, Qichun
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p. 2559 - 2565
(2014/02/14)
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- Formation of persulphate from sodium sulphite and molecular oxygen catalysed by H5PV2Mo10O40-aerobic epoxidation and hydrolysis
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The H5PV2Mo10O40 polyoxometalate catalysed the electron transfer oxidation of sulphite to yield a sulphite radical, SO3- that upon addition of O2 yielded a peroxosulphate species efficient for the H5PV2Mo10O40 catalysed epoxidation of alkenes. The acidic polyoxometalate further catalysed hydrolysis of the epoxide to give vicinal diols in high yields. This journal is
- Rubinstein, Amir,Carmeli, Raanan,Neumann, Ronny
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p. 13247 - 13249
(2015/05/20)
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- Heterogeneous catalytic epoxidation of olefin over a hydrothermally synthesized 3D phosphate bridged copper(II) framework
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A 3D copper phosphate, [Cu2(PO4)(OH)] n (1), has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction analysis. In [Cu2(PO4)(OH)] n, there are two types of copper centers having distorted trigonal bipyramidal geometry and distorted octahedral geometry that are connected by the μ2-bridging of each phosphate oxygen ultimately forming a η8-PO4 bridged 3D network. The compound exhibited excellent catalytic performance in olefin epoxidation. Epoxidation of styrene and substituted styrenes, as well as bulky olefins like cycloalkenes and long-chain alkenes, is efficiently catalyzed by [Cu2(PO 4)(OH)] n using tert-butylhydroperoxide in acetonitrile. The results obtained in the heterogeneous catalytic reactions show that the olefins are converted to the respective epoxides in good yield with high selectivity. [Cu2(PO4)(OH)] n was catalytically more active and selective in comparison to simple copper(II) phosphate salt in heterogeneous medium. The catalyst can be recycled and reused several times without significant loss of activity.
- Saha, Debraj,Maity, Tanmoy,Sen, Rupam
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p. 2444 - 2454
(2013/08/23)
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- Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide
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A family of iron complexes with general formula [Fe(II)( R,Y,XPyTACN)(CF3SO3)2], where R,Y,XPyTACN=1-[2′-(4-Y-6-X-pyridyl)methyl]-4,7-dialkyl-1,4, 7-triazacyclononane, X and Y refer to the groups at positions 4 and 6 of the pyridine, respectively, and R refers to the alkyl substitution at N-4 and N-7 of the triazacyclononane ring, are shown to be catalysts for efficient and selective alkene oxidation (epoxidation and cis-dihydroxylation) employing hydrogen peroxide as oxidant. Complex [Fe(II)(Me,Me,HPyTACN)(CF 3SO3)2] (7), was identified as the most efficient and selective cis-dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and under conditions where the olefin is not used in large amounts but instead is the limiting reagent. In the presence of 3 mol% of 7, 2 equiv. of H2O2 as oxidant and 15 equiv. of water, in acetonitrile solution, alkenes are cis-dihydroxylated reaching yields that might be interesting for synthetic purposes. Competition experiments show that 7 exhibits preferential selectivity towards the oxidation of cis olefins over the trans analogues, and also affords better yields and high [syn-diol]/[epoxide] ratios when cis olefins are oxidized. For aliphatic substrates, reaction yields attained with the present system compare favourably with state of the art Fe-catalyzed cis-dihydroxylation systems, and it can be regarded as an attractive complement to the iron and manganese systems described recently and which show optimum activity against electron-deficient and aromatic olefins. Copyright
- Prat, Irene,Font, David,Company, Anna,Junge, Kathrin,Ribas, Xavi,Beller, Matthias,Costas, Miquel
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supporting information
p. 947 - 956
(2013/05/08)
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- The effect of encapsulated Zn-POM on the catalytic activity of MIL-101 in the oxidation of alkenes with hydrogen peroxide
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Zinc monosubstituted Keggin heteropolyanion [PZnMo2W 9O39]5- was electrostatically bound to nanocages of MIL-101 polymer matrix. The Zn-POM@MIL-101 catalyst was characterized by XRD, N2 adsorption, atomic absorption (AAS), and FT-IR spectroscopic methods. The catalytic activity of the new composite material, Zn-POM@MIL-101, was assessed in the oxidation of alkenes using aqueous hydrogen peroxide as oxidant. Zn-POM@MIL-101/H2O2 catalytic system demonstrated good catalytic activity in the oxidation reactions. Zn-POM@MIL-101 was reusable for three catalytic cycles. While the MIL-101 matrix is an active catalyst in these oxidation reactions, the presence of Zn-POM significantly changed the selectivity and reaction times. Copyright
- Saedi, Zahra,Tangestaninejad, Shaharm,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 463 - 473
(2012/05/20)
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- Lanthanide carboxylate frameworks: Efficient heterogeneous catalytic system for epoxidation of olefins
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Two lanthanide-based three dimensional metal-organic frameworks (MOF) viz. [Nd(HCOO)3]n (1) and [Pr(HCOO)3]n (2) have been synthesized and characterized. Both the compounds have similar structure. In this study we have demonstrated that the compounds are highly efficient in catalyzing epoxidation of various cyclic and linear olefinic substrates. MOF compounds are stable and recyclable under the reaction conditions. Notably, MOF systems are remarkably more active and selective than the corresponding lanthanide oxide in epoxidation reaction of olefins.
- Sen, Rupam,Saha, Debraj,Koner, Subratanath
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experimental part
p. 124 - 130
(2012/04/10)
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- Envirocat (K10-MX)-catalyzed regioselective transformation of alkenes into iodohydrins and β-iodo ethers and further conversion of iodohydrins to epoxides using Al2O3-Na2Co3 under MWI
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Commercial K10 clay was converted to extremely efficient and environmentally friendly catalyst K10-MX for the preparation of iodohydrins and β-iodo ethers from alkenes (terminal as well as internal) using microwave irradiation. This method was further extended for the conversion of alkenes to epoxides via iodohydrin intermediate in a one-pot reaction system. Copyright Taylor & Francis Group, LLC.
- Shallu,Sharma,Singh, Jasvinder
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experimental part
p. 1306 - 1324
(2012/04/04)
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- Aerobic reduction of olefins by in situ generation of diimide with synthetic flavin catalysts
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A versatile reducing agent, diimide, can be generated efficiently by the aerobic oxidation of hydrazine with neutral and cationic synthetic flavin catalysts 1 and 2. This technique provides a convenient and safe method for the aerobic reduction of olefins, which proceeds with 1 equiv of hydrazine under an atmosphere of O2 or air. The synthetic advantage over the conventional gas-based method has been illustrated through high hydrazine efficiency, easy and safe handling, and characteristic chemoselectivity. Vitamin B2 derivative 6 acts as a highly practical, robust catalyst for this purpose because of its high availability and recyclability. Association complexes of 1b with dendritic 2,5-bis(acylamino)pyridine 15 exhibit unprecedented catalytic activities, with the reduction of aromatic and hydroxy olefins proceeding significantly faster when a higher-generation dendrimer is used as a host pair for the association catalysts. Contrasting retardation is observed upon similar treatment of non-aromatic or non-hydroxy olefins with the dendrimer catalysts. Control experiments and kinetic studies revealed that these catalytic reactions include two independent, anaerobic and aerobic, processes for the generation of diimide from hydrazine. Positive and negative dendrimer effects on the catalytic reactions have been ascribed to the specific inclusion of hydrazine and olefinic substrates into the enzyme-like reaction cavities of the association complex catalysts. Copyright
- Imada, Yasushi,Iida, Hiroki,Kitagawa, Takahiro,Naota, Takeshi
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supporting information; experimental part
p. 5908 - 5920
(2011/07/07)
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- A flexible nonporous heterogeneous catalyst for size-selective oxidation through a bottom-up approach
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Size does matter: The nonporous tetra-n-butylammonium salt of silicodecatungstate, synthesized through a bottom-up approach, heterogeneously catalyzes the size-selective oxidation of various organic compounds, including olefins, sulfides, and organosilanes, with aqueous H2O2 in ethyl acetate. The catalyst can be easily separated by filtration and reused several times with retention of high catalytic activity. Copyright
- Mizuno, Noritaka,Uchida, Sayaka,Kamata, Keigo,Ishimoto, Ryo,Nojima, Susumu,Yonehara, Koji,Sumida, Yasutaka
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supporting information; experimental part
p. 9972 - 9976
(2011/03/18)
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- Regioselective epoxidation of different types of double bonds over large-pore titanium silicate Ti-β
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Regioselective epoxidation of different types of double bonds located within the cyclic and acyclic parts of bulky olefins has been investigated using large-pore titanium silicate Ti-β in the presence of dilute aqueous H 2O2 as oxidant under mild liquid-phase conditions. Our experimental results revealed that side-chain vinylic double bonds are selectively epoxidized than those in the cyclohexene-ring. The epoxidation tendency of various bulky olefins with different positional and/or geometric isomers over Ti-β follows the order: terminal -CC- > ring -CC- ≈ bicyclic ring -CC- > allylic C - H bond. Unlike 4-vinyl-1-cyclohexene, epoxidation of an equimolar mixture of cyclohexene and 1-hexene under identical conditions using Ti-β exhibits completely different selectivity and product distributions. Steric factor and accessibility of reactants to active Ti-sites are responsible for the observed regioselectivity of bulky alkenes.
- Sasidharan, Manickam,Bhaumik, Asim
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experimental part
p. 60 - 67
(2010/12/18)
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- Neutral flavins: Green and robust organocatalysts for aerobic hydrogenation of olefins
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"Chemical Equation Presented" Various olefins can be hydrogenated quantitatively with neutral flavin 2 catalysts in the presence of 1 -2 equiv of hydrazine under 1 atm of O2. Vitamin B2 derivative 2g acts as a highly efficient and robust catalyst for the present environmentally benign process producing water and nitrogen gas as the only waste products
- Imada, Yasushi,Kitagawa, Takahiro,Ohno, Takashi,Iida, Hiroki,Naota, Takeshi
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supporting information; experimental part
p. 32 - 35
(2010/03/04)
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- A convenient methodology for the chemoselective reduction of a wide variety of functionalized alkenes
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An efficient method to effect chemoselective reduction of alkenes (including trisubstituted olefins) possessing various sensitive and/or reducible groups such as acetals, allylic alcohols, benzyl ethers, epoxides, esters, halides, nitriles, and sulfones is reported. The reduction is facile at 0 °C in aqueous N,N-dimethylacetamide containing sodium borohydride in the presence of 15 mol % ruthenium(III) chloride. Regioselective reduction of dienes is also feasible if the double bonds are sufficiently different in their structural environment.
- Babler, James H.,White, Nicholas A.
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experimental part
p. 439 - 441
(2010/03/04)
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- Palladium nanoparticles-catalyzed chemoselective hydrogenations, a recyclable system in water
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Chemoselective hydrogenation of double bonds in the presence of various functional groups occurred in high yields using water or toluene as solvent, and Pd nanoparticles as catalyst. Up to nine recyclings were achieved in water without decrease of the catalyst activity.
- Callis, Nuria Miro,Thiery, Emilie,Le Bras, Jean,Muzart, Jacques
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p. 8128 - 8131
(2008/03/13)
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- The nature of oxidizing particles in the catalytic decomposition of H 2O2 with Fe(III) salts in acetonitrile
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Different oxidizing particles were shown to form in the decomposition of hydrogen peroxide in acetonitrile catalyzed by the Fe(ClO4) 3 and FeCl3 salts, namely, the HO? radical and, evidently, the ferryl ion (FeIV = O)2+, respectively. This difference was established for the examples of oxygenation of alkanes and olefins. Clear-cut differences in the kinetic behavior of the two catalytic systems and their oxidation selectivity were observed.
- Kozlov,Nizova,Shul'pin
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p. 184 - 187
(2007/10/03)
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- Hydrogen peroxide oxygenation of alkanes including methane and ethane catalyzed by iron complexes in acetonitrile
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This paper describes an investigation of the alkane oxidation with hydrogen peroxide in acetonitrile catalyzed by iron(III) perchlorate (1), iron(III) chloride (2), iron(III) acetate (3) and a binuclear iron(III) complex with 1,4,7-triazacyclononane (4). The corresponding alkyl hydroperoxides are the main products. Nevertheless in the kinetic study of cyclohexane oxidation, the concentrations of oxygenates (cyclohexanone and cyclohexanol) were measured after reduction of the reaction solution with triphenylphosphine (which converts the cyclohexyl hydroperoxide to the cyclohexanol). Methane and ethane can be also oxidized with TONs up to 30 and 70, respectively. Chloride anions added to the oxidation solution with 1 activate the perchlorate iron derivative in acetonitrile, whereas the water as additive inactivates 2 in the H 2O2 decomposition process. Pyrazine-2-carboxylic acid (PCA) added to the reaction mixture decreases the oxidation rate if 1 or 2 are used as catalysts, whereas compounds 3 and 4 are active as catalysts only in the presence of small amount of PCA. The investigation of kinetics and selectivities of the oxidations demonstrated that the mechanisms of the reactions are different. Thus, in the oxidations catalyzed by the 1, 3+PCA and 4+ PCA systems the main oxidizing species is hydroxyl radical, and the oxidation in the presence of 2 as a catalyst has been assumed to proceed (partially) with the formation of ferryl ion, (FeIV=O)2+. In the oxidation catalyzed by the 4+PCA system (TONs attain 240) hydroxyl radicals were generated in the rate-determining step of monomolecular decomposition of the iron diperoxo adduct containing one PCA molecule. A kinetic model of the process which satisfactorily describes the whole set of experimental data was suggested. The constants of supposed equilibriums and the rate constant for the decomposition of the iron diperoxo adduct with PCA were estimated.
- Shul'pin, Georgiy B.,Nizova, Galina V.,Kozlov, Yuriy N.,Cuervo, Laura Gonzalez,Su?ss-Fink, Georg
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p. 317 - 332
(2007/10/03)
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- Polyoxofluorometallates and use thereof as catalysts for the epoxidation of alkenes
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The invention provides a process for the catalytic epoxidation of an alkene comprising contacting a transition metal substituted polyoxofluorometalate and molecular oxygen with said alkene.
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- High conversion of olefins to cis-diols by non-heme iron catalysts and H2O2.
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Efficient and highly stereoselective oxidation of olefins to cis-diols as the major product is obtained by using biomimetic non-heme FeII catalysts in combination with H2O2.
- Ryu, Ju Yeon,Kim, Jinheung,Costas, Miquel,Chen, Kui,Nam, Wonwoo,Que Jr., Lawrence
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p. 1288 - 1289
(2007/10/03)
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- TiO2-Photocatalyzed Epoxidation of 1-Decene by H2O2 under Visible Light
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1-Decene was converted to 1,2-epoxydecane on UV-irradiated TiO2 powder using molecular oxygen as the oxygen source. Other main products were nonanal and 2-decanone. For anatase-form TiO2 powders, the reaction rate was hardly affected by addition of hydrogen peroxide to the solution. In contrast, for rutile-form TiO2 powders, the rate of epoxide generation was significantly increased by addition of hydrogen peroxide. In this case, the reaction occurred under visible light as well as UV light. The selectivity of the production of 1,2-epoxydecane was higher under visible light than under UV light. The conversion efficiency of an incident photon to 1,2-epoxydecane was about 2 percent when irradiated with visible light in the range 440-480 nm. UV-visible diffuse reflection spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested the generation of a Ti-η2-peroxide on rutile TiO2 surface after treatment with hydrogen peroxide. The initial step of the reaction under visible light was attributed to a photochemical reaction of this peroxide with 1-decene.
- Ohno, Teruhisa,Masaki, Yuji,Hirayama, Seiko,Matsumura, Michio
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p. 163 - 168
(2007/10/03)
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- Highly chemoselective hydrogenation with retention of the epoxide function using a heterogeneous Pd/C - Ethylenediamine catalyst and THF
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In general, palladium-carbon (Pd/C) catalyzed hydrogenation of epoxides affords the corresponding primary and secondary alcohols as a mixture. It has been found that the catalytic activity of a Pd/C - ethylenediamine complex catalyst [Pd/C(en)] in the hydrogenolysis of epoxide functions is drastically reduced. Herein we describe a mild and chemoselective method for the hydrogenation of olefin, nitro, and azide functions with retention of the epoxide function. The chemoselectivity was accomplished by using a combination of 5% Pd/C(en) and THF as solvent. A significant drop in the chemoselectivity of the hydrogenation is observed with 5% Pd/C(en) in MeOH. These results reinforce the utility of epoxides as important precursors of alcohols in synthetic chemistry.
- Sajiki, Hironao,Hattori, Kazuyuki,Hirota, Kosaku
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p. 2200 - 2204
(2007/10/03)
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- Epoxldation of terminal alkenes with oxygen and 2-ethyl hexanal, without added catalyst or solvent
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Two terminal alkenes, 1-decene and methyl 10-undecenoate, were epoxidized with oxygen using 2-ethyl hexanal as coreactant without any added solvent. Under optimal conditions, the yield of methyl 10, 11-epoxyundecanoate was 98.7%. 2-Ethyl hexanal was oxidized mainly to 2-ethyl hexanoic acid and also formed some byproducts. The tested metal complexes retarded the epoxidation reaction slightly and increased the amount of byproducts of 2-ethyl hexanal.
- Lehtinen, Christel,Brunow, C?sta
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p. 101 - 103
(2013/09/08)
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- Electroorganic synthesis 65. Anodic homocoupling of carboxylic acids derived from fatty acids
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Fatty acid derived carboxylic acids with double bonds, hydroxy-, amino-, keto-, ester- and epoxy groups are anodically coupled to dimers (Kolbe electrolysis) in 29 to 81% yield and up to a 2.5 mol scale. Problems due to the low conductivity of fatty acid salts were overcome by the use of a flow cell with a narrow electrode gap. Fatty acids with branched alkyl chains gave dimers with interesting emulsifying properties. Dimethyl hexadecanedioate, accessible from methyl azelate, could be cyclized and further converted into homomuscone and muscone in a few steps. A commercial mixture of dimeric fatty acids (C36-dicarboxylic acids) has been coupled to give C70-diesters. Acta Chemica Scandinavica 1998. Part 64: Nielsen, M. F., Batanero, B.,.
- Weiper-Idelmann, Andreas,Aus Dem Kahmen, Martin,Schaefer, Hans J.,Gockeln, Marianne
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p. 672 - 682
(2007/10/03)
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- Oxidation of Allenes and Alkynes with Hydrogen Peroxide Catalyzed by Cetylpyridinium Peroxotungstophosphate (PCWP)
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The oxidation of allenes and alkynes with hydrogen peroxide catalyzed by peroxotungstophosphate (PCWP) was examined.A variety of allenes were first converted into the corresponding α-ethoxy ketones upon treatment with 35percent H2O2 under the influence of PCWP in a mixed solvent consisting of ethanol and dichloromethane.When the reaction was carried out using tert-butyl alcohol as a solvent, approximately a 1:1 regioisomeric mixture of α-hydroxy ketones was obtained along with a small amount of α-tert-butoxy ketone.Oxidation of internal alkynes such as 4-octyne by the PCWP-H2O2 system under phase-transfer conditions using chloroform produced α,β-epoxy ketones in good yields.The same reaction in a mixed solvent of ethanol and chloroform gave α,β-unsaturated ketones rather than α,β-epoxy ketones.Plausible reaction paths are proposed for the oxidation of allenes and alkynes by the PCWP-H2O2 system.
- Sakaguchi, Satoshi,Watase, Seiji,Katayama, Yuji,Sakata, Yasuyuki,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 5681 - 5686
(2007/10/02)
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- A New Route to Epoxides and Ketones by m-Chloroperbenzoic Acid Oxidation of β-Hydroxyalkyl Phenyl Selenides and Tellurides
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Treatment of primary (β-hydroxy)alkyl phenyl selenides with m-chloroperbenzoic acid (3-5 mol equiv.) in tetrahydrofuran or methanol gives the corresponding epoxides in high yield. cis-1-Methylene-4-t-butylcyclohexane oxide is obtained stereospecifically from 4-t-butyl-1-(phenylselenomethyl)cyclohexanol prepared by the addition of α-(phenylseleno)methyl anion to 4-t-butylcyclohexanone.On the other hand, similar oxidation of secondary (β-hydroxy)alkyl phenyl selenides affords the unexpected carboxylic acids or their esters.When a phenyl group is present on the carbon bearing the OH moiety in β-hydroxyselenides and tellurides , the oxidation is accompanied by phenyl migration to afford ketones.The reaction can be applied to one-carbon-homologated ring expansion of the benzene-ring-fused cyclic ketones by combining with the addition of an α-(phenylseleno)methyl or α-(phenyltelluro)methyl moiety to the ketones.
- Uemura, Sakae,Ohe, Kouichi,Sugita, Nobuyuki
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p. 1697 - 1703
(2007/10/02)
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- The Epoxidation of C5 - C10 Alkenes with Hydrogen Peroxide Catalyzed by Mo Compounds in Two-phase Solvents
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The epoxidation of terminal alkenes such as 1-heptene, 1-octene, 1-decene, styrene (1), α-methylstyrene, and allyl chloride, and inner alkenes such as α-pinene, cyclopentene, cyclohexene (2) and cyclooctene was carried out with aqueous 60percent hydrogen peroxide in the presence of molybdenum blue (Mob)-bis(tributyltin) oxide (3) using a two-phase solvent of chloroform-water at 25 deg C.All these olefins gave epoxides in 98 to 48percent yields.In the case of 1 and 2, the addition of ammonia greatly increased the yields of epoxides; the yield reached 78percent and 83percent, respectively, after 7 h.Various kinds of amines and organotin compounds were examined as co-catalysts and their effects were discussed.
- Kamiyama, Tsutomu,Inoue, Masami,Kashiwagi, Hiroshi,Enomoto, Saburo
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p. 1559 - 1562
(2007/10/02)
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- Oxidative Conversion of β-Hydroxyselenides to Epoxides and Ketones with meta-Chloroperbenzoic Acid
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Treatment of β-hydroxy-primary-alkyl and β-hydroxy-β-phenyl-primary-alkyl phenyl selenides with 3-5 equiv. of m-chloroperbenzoic acid in methanol or tetrahydrofuran gives the corresponding epoxides and phenyl migrated ketones, respectively in high yields.
- Uemura, Sakae,Ohe, Kouichi,Sugita, Nobuyuki
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p. 111 - 112
(2007/10/02)
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- THE SYNTHETIC UTILITY OF DIOXYPHOSPHORANES IN ORGANIC SYNTHESIS
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Diethoxytriphenylphosphorane, DTPP, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild and efficient cyclodehydration of diols to cyclic ethers in neutral media.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively, with DTPP.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes in the presence of DTPP and the reaction conditions dictate whether epoxides, ketones, or allylic alcohols are obtained.
- Robinson, Philip L.,Kelly, Jeffery W.,Evans, Slayton A.
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- Diethoxytriphenylphosphorane: A Mild, Regioselective Cyclodehydrating Reagent for Conversion of Diols to Cyclic Ethers. Stereochemistry, Synthetic Utility, and Scope
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Diethoxytriphenylphosphorane, Ph3P(OEt)2, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild cyclodehydration (40-110 deg C) of diols to cyclic ethers in neutral media.The regioselectivity in the closure of (S)-(+)-propane-1,2-diol and (R)-(-)-pentane-1,4-diol with Ph3P(OEt)2 is high (81-82 percent) while the cyclodehydration of (S)-(+)-phenylethane-1,2-diol gives racemized (+/-)-styrene oxide.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively with Ph3P(OEt)2.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes (or ?-dioxyphosphoranes) in the presence of Ph3P(OEt)2, and, depending on conditions, the 1,3,2-dioxaphospholanes are selectively converted to epoxides, ketones or allylic alcohols.The carbonyl compounds arise from 1,2-hydride and 1,2-methyl migrations; the allylic alcohols are derived from thermolytic eliminations. trans-1,2-Cyclohexanediols afford essentially quantitative yields (>95 percent) of the cyclohexene oxides while cis-1,2-cyclohexanediol gives the stable 1,3,2-dioxaphospholane with Ph3P(OEt)2 which decomposes under thermal conditions to cyclohexanone (90 percent).Ph3P(OEt)2 is extremely useful for conversion of "sensitive" 1,2-diols to acidic and /or thermally labile epoxides as demonstrated by the quantitative conversion of 9,10-dihydro-trans-9,10-phenanthrenediol to 9,10-dihydrophenanthrene oxide and 2α,10-pinanediol to 2α,10-epoxypinane.
- Robinson, Philip L.,Barry, Carey N.,Kelly, Jeffery W.,Evans, Slayton A.
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p. 5210 - 5219
(2007/10/02)
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- Palladium-catalysed oxidation of alcohols with carbon tetrachloride, formation of 4,4,4-trichloro ketones from allylic alcohols and carbon tetrachlorid
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Pd salts catalyse oxidation of alcohols with CCl4 in the presence of K2CO3. Primary alcohols are oxidised to esters, and secondary alcohols to ketones. CCl4 is converted to CHCl3. The reaction of allylic alcohols bearing a terminal olefinic bond with CCl4 or BrCCl3 in the presence of palladium catalyst at 110° affords 4,4,4-trichloro ketones. At 40°, simple adducts of CCl4 or BrCCl3 having a halohydrin structure are obtained, which are converted to the corresponding trichloro ketones by the catalysis of palladium. Various halohydrins are converted to ketones by Pd catalysis.
- nagashima, Hideo,Sato, Koji,Tsuii, Jiro
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p. 5645 - 5651
(2007/10/02)
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- A new approach to the air oxidation of alkenes employing metal nitro complexes as catalysts
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Alkenes are stoichiometrically and, in the presence of air, catalytically oxidized by cis-bis(acetonitrile)chloronitropalladium(II) (1). Oxidation of monosubstituted terminal alkenes and trans-cyclooctene yields the corresponding ketone, oxidation of cyclopentene and cyclohexene the corresponding allyl alcohol, and oxidation of bicyclic alkenes the corresponding epoxide, each with good selectivity for the respective product. Other alkenes give varying mixtures of the above products together with, in some cases, the α,β-unsaturated ketone. Vinyl ethers yield the corresponding ester while (trimethylsilyl)ethylene yields (trimethylsilyl)acetaldehyde. The selectivities are rationalized on the basis of ease of β-hydrogen elimination in observed intermediate heterometallacyclopentane complexes 3 formed by nucleophilic attack of the nitro oxygen atom on the coordinated alkene in alkene nitro complexes 2. The general role of metallacycles in metal-mediated alkene oxidations and the advantages and disadvantages of intra- vs. intermolecular metal nitro catalyzed alkene oxidations are discussed.
- Andrews, Mark A.,Chang, Tony C.-T.,Cheng, Chi-Wen F.,Kelly, Kevin P.
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p. 1777 - 1785
(2008/10/08)
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- NOVEL ONE STEP SYNTHESIS OF EPOXIDES FROM β-HYDROXY-SELENIDES AND SULFIDES
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Epoxides are stereoselectively prepared in one step from β-hydroxy selenides and β-hydroxy sulfides in a process which involves dichlorocarbene
- Laboureur, J. L.,Dumont, W.,Krief, A.
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p. 4569 - 4572
(2007/10/02)
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- CHLORINATION AND CYCLODEHYDRATION OF 1,2-DIOLS WITH THE "TRIPHENYLPHOSPHINE-TETRACHLOROMETHANE-POTASSIUM CARBONATE" REAGENT
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The yields of the epoxides obtained from the reaction of 1,2-diols with the "triphenylphosphine-tetrachloromethane-potassium carbonate reagent" range from 27-85percent depending on the relative concentration of triphenylphosphine and diol.In the absence of heterogeneous potassium carbonate, reactions of 1,2-diols with triphenylphosphine-tetrachloromethane give largely 1,2-chlorohydrins.
- Barry, Carey N.,Evans, Slayton A.
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p. 661 - 664
(2007/10/02)
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- The Catalyzed Liquid-Phase Oxidation of Normal Alk-1-enes
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The efficiencies of various homogeneous soluble transition metal compounds to increase epoxide yields in the autoxidation of alk-1-enes were studied.Combinations of typical autoxidation and typical epoxidation catalysts were also used.It was proved through balance experiments, that in no case yields of 50percent or more of the corresponding epoxides were obtained.The simple mechanism (epoxidation via allylic hydroperoxides) assumed only insufficiently reflects the reaction course.
- Barth, U.,Fiedler, H.,Gross, G.,Lauterbach, G.,Schnurpfeil, D.
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p. 887 - 901
(2007/10/02)
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