- A novel reaction in ionic liquids: Selective cyclization of 1-dodecene to cyclododecane under moderate pressure
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A novel reaction of cyclization of 1-dodecene to cyclododecane with high selectivity, especially under moderate pressure, is found in ethanol buffered chloroaluminate ionic liquids with easy separation of product due to the immiscibility with ionic liquids.
- Qiao, Kun,Deng, Youquan
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- Diastereomeric cyclic tris-allenes
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Both diastereomers of the tris-allene, cyclododeca-1,2,5,6,9,10-hexaene have been obtained using a triple cyclopropylidene-allene rearrangement. On the NMR timescale, one has D3 symmetry, and is the smallest hydrocarbon synthesised to have this symmetry, and the second has C2 symmetry.
- Mustafa, Hussein H.,Baird, Mark S.,Al Dulayymi, Juma'A R.,Tverezovskiy, Viacheslav V.
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- 5,10-Dihydro-Silanthrene as a Reagent for the Barton-McCombie Reaction
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The deoxygenation of secondary alcohols via thionoesters with the use of 5,10-dihydrosilanthrene as the radical reducing agent has been studied in detail.The ability of hydrogen donation of this silane has been measured using the one-carbon ring expansion of 1-(2-oxocyclopentyl)ethyl radical as a timing device.
- Gimisis, T.,Ballestri, M.,Ferreri, C.,Chatgilialoglu, C.,Boukherroub, R.,Manuel, G.
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- Discrimination of Rotational Isomeric States in Cycloalkanes by Solid-State CP-MAS 13C NMR Spectroscopy
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The solid-state behavior of three cycloalkanes, cyclododecane, cyclotetraeicosane, and cyclohexatriacontane, was investigated by means of temperature dependent magic angle cross-polarization 13C NMR experiments.For the two smaller ring molecules a state of high internal mobility like the "rotator phase" in n-alkanes was detected.It could be correlated with a phase transition in the solid state visible by means of DSC.In the case of (CH2)12 this is 151 K below the melting point, and in the case of (CH2)24 it is 25 K below the melting transition.The CP-MAS 13C NMR spectra show a transition from the fast exchange to the slow exchange regime of magnetically nonequivalent states.By comparison with X-ray diffraction data the well-resolved resonance signals for the low-temperature phases were assigned to molecular segments distinguished by the rotational isomeric states of the carbon-carbon bonds.Chemical shift differences due to conformational isomerism were as large as 12 ppm; thus, they exceed "packing effects" by far.
- Moeller, Martin,Gronski, Wolfram,Cantow, Hans Joachim,Hoecker, Hartwig
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- Sustainable System for Hydrogenation Exploiting Energy Derived from Solar Light
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Herein described is a sustainable system for hydrogenation that uses solar light as the ultimate source of energy. The system consists of two steps. Solar energy is captured and chemically stored in the first step; exposure of a solution of azaxanthone in ethanol to solar light causes an energy storing dimerization of the ketone to produce a sterically strained 1,2-diol. In the second step, the chemical energy stored in the vicinal diol is released and used for hydrogenation; the diol offers hydrogen onto alkenes and splits back to azaxanthone, which is easily recovered and reused repeatedly for capturing solar energy.
- Ishida, Naoki,Kamae, Yoshiki,Ishizu, Keigo,Kamino, Yuka,Naruse, Hiroshi,Murakami, Masahiro
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supporting information
p. 2217 - 2220
(2021/02/16)
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- Flow Chemistry under Extreme Conditions: Synthesis of Macrocycles with Musklike Olfactoric Properties
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Starting from small cyclic ketones, continuous flow synthesis is used to produce medium-sized rings and macrocycles that are relevant for the fragrance industry. Triperoxides are important intermediates in this process and are pyrolyzed at temperatures above 250 °C. The synthesis is carried out in two continuously operated flow reactors connected by a membrane-operated separator. The practicality of flow chemistry is impressively demonstrated in this work by the use of hazardous reagent mixtures (30% H2O2, 65% HNO3) and the pyrolysis of no less problematic peroxides. All new macrocycles were tested for their olfactory properties in relation to musk.
- Seemann, Alexandra,Panten, Johannes,Kirschning, Andreas
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supporting information
p. 13924 - 13933
(2021/05/29)
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- Hydrogenation of 1,5,9-Cyclododecatriene in a Three-Phase System in the Presence of Nickel Nanoparticles Supported on NаX Zeolite
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The hydrogenation of 1,5,9-cyclododecatriene in the presence of nanostructured Ni catalysts, supported with NaX zeolite, in a flow-through reactor at atmospheric hydrogen pressure was investigated. Nickel nanoparticles on the support surface were prepared by chemical reduction of the precursor (NiCl2) with NaBH4 and NH2NH2. The effect exerted on the yield of hydrogenation products by the nominal residence time of the gas phase in the reaction zone and by the process temperature was considered, and the catalyst operation life was analyzed. The catalysts showed high activity and allowed preparation of cyclododecane in ~100% yield at a process temperature of up to 160°С.
- Nebykov,Popov, Yu. V.,Mokhov,Shcherbakova,Zotov, Yu. L.
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p. 110 - 115
(2021/03/18)
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- A New Protocol for Catalytic Reduction of Alkyl Chlorides Using an Iridium/Bis(benzimidazol-2′-yl)pyridine Catalyst and Triethylsilane
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The reduction of alkyl chlorides using triethylsilane is investigated. Primary, secondary, tertiary, and benzylic C-Cl bonds are effectively converted into C-H bonds using an [IrCl(cod)] 2/2,6-bis(benzimidazol-2′-yl)pyridine catalyst system. This catalyst system is quite simple since the tridentate N-ligand can be easily prepared in one step from commercially available reagents.
- Fukuyama, Takahide,Hamada, Yuki,Ryu, Ilhyong
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p. 3404 - 3408
(2021/07/14)
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- Method for hydrogenolysis of halides
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The invention discloses a method for hydrogenolysis of halides. The invention discloses a preparation method of a compound represented by a formula I. The preparation method comprises the following step: in a polar aprotic solvent, zinc, H2O and a compound represented by a formula II are subjected to a reaction as shown in the specification, wherein X is halogen; Y is -CHRR or R; hydrogenin H2O exists in the form of natural abundance or non-natural abundance. According to the preparation method, halide hydrogenolysis can be simply, conveniently and efficiently achieved through a simple and mild reaction system, and good functional group compatibility and substrate universality are achieved.
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Paragraph 0232; 0239-0241
(2021/01/11)
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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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- Synthesis of mesoporous ZSM-5 zeolites and catalytic cracking of ethanol and oleic acid into light olefins
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Conversion of biomass-derived chemicals into light olefins is a promising method to maintain sustainable development of light olefin industry. In this study, three mesoporous ZSM-5 zeolites (MZSM-5-A, MZSM-5-B and MZSM-5-C) with major pore diameter about 4.8 nm, 16 nm and 22 nm were synthesized using a hydrothermal method by utilizing different templates. The catalytic activity of catalysts was studied by catalytic cracking of ethanol and oleic acid. The influence of reaction temperature on conversion and product selectivity was investigated. The characterization of ZSM-5 samples showed that the orders of the external surface area and mesopore volume were MZSM-5-C > MZSM-5-B > MZSM-5-A > conventional HZSM-5. In ethanol to light olefin reaction, MZSM-5-C achieved the highest light olefin yield (318.3 mL g?1) and ethylene selectivity (42.3%) at 400 °C. In oleic acid to light olefin reaction, MZSM-5-B achieved a complete conversion of oleic acid at 500 °C, and obtained the highest light olefin selectivity (38.1%) at 550 °C. The difference may be relevant to the size and chemical structure of feedstock molecular as well as the acidity of catalysts. Regardless of ethanol or oleic acid as feedstock, introduction of mesopore in zeolites significantly enhanced the light olefin yield and selectivity.
- Zhao, Tingting,Li, Fuwei,Yu, Hongchang,Ding, Shilei,Li, Zhixia,Huang, Xinyuan,Li, Xiang,Wei, Xiaohan,Wang, Zhenlin,Lin, Hongfei
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p. 101 - 110
(2019/02/24)
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- 4-Methyltetrahydropyran (4-MeTHP): Application as an Organic Reaction Solvent
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4-Methyltetrahydropyran (4-MeTHP) is a hydrophobic cyclic ether with potential for industrial applications. We herein report, for the first time, a comprehensive study on the performance of 4-MeTHP as an organic reaction solvent. Its broad application to organic reactions includes radical, Grignard, Wittig, organometallic, halogen-metal exchange, reduction, oxidation, epoxidation, amidation, esterification, metathesis, and other miscellaneous organic reactions. This breadth suggests 4-MeTHP can serve as a substitute for conventional ethers and harmful halogenated solvents. However, 4-MeTHP was found incompatible with strong Lewis acids, and the C?O bond was readily cleaved by treatment with BBr3. Moreover, the radical-based degradation pathways of 4-MeTHP, THP and 2-MeTHF were elucidated on the basis of GC-MS analyses. The data reported herein is anticipated to be useful for a broad range of synthetic chemists, especially industrial process chemists, when selecting the reaction solvent with green chemistry perspectives.
- Kobayashi, Shoji,Tamura, Tomoki,Yoshimoto, Saki,Kawakami, Takashi,Masuyama, Araki
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p. 3921 - 3937
(2019/11/11)
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- Colloid and Nanosized Catalysts in Organic Synthesis: XIX.1 Influence of the Support Nature on Hydrogenation Catalysis of Cyclic Olefins by Nickel Nanoparticles
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Gas-phase hydrogenation of cycloalkenes in the presence of nickel nanoparticles supported on Ceokar-2, BAU-A activated carbon, alumina, and NaX zeolite proceeds at 140–240°C and atmospheric pressure of hydrogen. The conversion and selectivity depend on the type of support and on the hydrogen excess.
- Popov, Yu. V.,Mokhov,Nebykov,Shcherbakova,Dontsova
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- Hybrid Catalysis Enabling Room-Temperature Hydrogen Gas Release from N-Heterocycles and Tetrahydronaphthalenes
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Hybrid catalyst systems to achieve acceptorless dehydrogenation of N-heterocycles and tetrahydronaphthalenes-model substrates for liquid organic hydrogen carriers-were developed. A binary hybrid catalysis comprising an acridinium photoredox catalyst and a Pd metal catalyst was effective for the dehydrogenation of N-heterocycles, whereas a ternary hybrid catalysis comprising an acridinium photoredox catalyst, a Pd metal catalyst, and a thiophosphoric imide organocatalyst achieved dehydrogenation of tetrahydronaphthalenes. These hybrid catalyst systems allowed for 2 molar equiv of H2 gas release from six-membered N-heterocycles and tetrahydronaphthalenes under mild conditions, i.e., visible light irradiation at rt. The combined use of two or three different catalyst types was essential for the catalytic activity.
- Kato, Shota,Saga, Yutaka,Kojima, Masahiro,Fuse, Hiromu,Matsunaga, Shigeki,Fukatsu, Arisa,Kondo, Mio,Masaoka, Shigeyuki,Kanai, Motomu
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supporting information
p. 2204 - 2207
(2017/02/23)
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- Catechols as Sources of Hydrogen Atoms in Radical Deiodination and Related Reactions
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When used with trialkylboranes, catechol derivatives, which are low-cost and low toxicity, are valuable hydrogen atom donors for radical chain reactions involving alkyl iodides and related radical precursors. The system 4-tert-butylcatechol/triethylborane has been used to reduce a series of secondary and tertiary iodides, a xanthate, and a thiohydroxamate ester. Catechol derivatives are right in the optimal kinetic window for synthetic applications, as demonstrated by highly efficient radical cyclizations. Cyclizations leading to the formation of quaternary centers can be performed in an all-at-once process (no slow addition of the hydrogen atom donor) at standard concentrations. The H-donor properties of catechol derivatives can be fine-tuned by changing their substitution pattern. In slow radical cyclization processes, an enhanced ratio of cyclized/uncyclized products was obtained by using 3-methoxycatechol instead of 4-tert-butylcatechol.
- Povie, Guillaume,Ford, Leigh,Pozzi, Davide,Soulard, Valentin,Villa, Giorgio,Renaud, Philippe
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supporting information
p. 11221 - 11225
(2016/10/13)
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- Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles
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Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.
- Kojima, Masahiro,Kanai, Motomu
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supporting information
p. 12224 - 12227
(2016/10/13)
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- Hydrogenation of alkenes over nickel nanoparticles under atmospheric pressure of hydrogen
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Nickel nanoparticles have been shown to be an accessible catalyst which allows hydrogenation of unsaturated compounds to be accomplished under atmospheric pressure of hydrogen at relatively low temperatures. Linear and cyclic alkenes, styrene and norbornene derivatives, as well as pinenes and camphene have been smoothly hydrogenated under these conditions. In some cases, selective hydrogenation of unsaturated carbon–carbon bond is possible with the other functional group remaining intact.
- Mokhov,Popov, Yu. V.,Nebykov
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p. 319 - 323
(2016/06/06)
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- Reduced graphene oxide supported nickel-palladium alloy nanoparticles as a superior catalyst for the hydrogenation of alkenes and alkynes under ambient conditions
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Addressed herein is the superior catalytic performance of reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) for the direct hydrogenation of alkenes and alkynes to alkanes, which surpasses the commercial Pd/C catalyst both in activity and stability. A variety of cyclic or aromatic alkenes and alkynes (a total of 17 examples) were rapidly reduced to the corresponding alkanes with high yields (>99%) via the presented direct hydrogenation protocol under ambient conditions. Compared to the commercially available Pd/C (10 wt%) catalyst, the rGO-Ni30Pd70 catalyst provided higher yields in shorter reaction times under the optimized conditions. Moreover, the rGO-Ni30Pd70 catalysts were more stable and durable than the commercial Pd/C catalysts by preserving their initial activity after five consecutive runs in the hydrogenation reactions.
- ?etinkaya, Yasin,Metin, ?nder,Balci, Metin
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p. 28538 - 28542
(2016/04/08)
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- The Retro-Hydroformylation Reaction
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Hydroformylation, a reaction that adds carbon monoxide and dihydrogen across an unsaturated carbon-carbon multiple bond, has been widely employed in the chemical industry since its discovery in 1938. In contrast, the reverse reaction, retro-hydroformylation, has seldom been studied. The retro-hydroformylation reaction of an aldehyde into an alkene and synthesis gas (a mixture of carbon monoxide and dihydrogen) in the presence of a cyclopentadienyl iridium catalyst is now reported. Aliphatic aldehydes were converted into the corresponding alkenes in up to 91 % yield with concomitant release of carbon monoxide and dihydrogen. Mechanistic control experiments indicated that the reaction proceeds by retro-hydroformylation and not by a sequential decarbonylation-dehydrogenation or dehydrogenation-decarbonylation process.
- Kusumoto, Shuhei,Tatsuki, Toshiumi,Nozaki, Kyoko
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supporting information
p. 8458 - 8461
(2015/11/27)
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- Mechanism of low-molecular alkenes interaction with sulfur-containing spatially hindered phenols under conditions of thermal modification of polymer materials
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Abstract Transformations in the course of high-temperature modification of polyolefins under action of sulfur-containing modifiers have been studied using hexene-1 and hexane as model compounds. Composition of products of thermolysis of bis[3-(3,5-di-tert
- Krysin,Pokrovskii,Nefedov,Shundrina,Selivanov
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p. 659 - 666
(2015/05/05)
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- Cyclooctane metathesis catalyzed by silica-supported tungsten pentamethyl [(ΞSiO)W(Me)5]: Distribution of macrocyclic alkanes
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Metathesis of cyclic alkanes catalyzed by the new surface complex [(ΞSiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula CnH2n are the result of either a ring contraction or ring expans
- Riache, Nassima,Callens, Emmanuel,Samantaray, Manoja K.,Kharbatia, Najeh M.,Atiqullah, Muhammad,Basset, Jean-Marie
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supporting information
p. 15089 - 15094
(2015/02/19)
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- Promotional effect of Fe on performance of Ni/SiO2 for deoxygenation of methyl laurate as a model compound to hydrocarbons
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Ni/SiO2, Fe/SiO2 and bimetallic FeNi/SiO2 catalysts with different Fe/Ni weight ratios were prepared by incipient-wetness impregnation method for the deoxygenation of methyl laurate to hydrocarbons. It was found that a suitable amount of Fe enhanced the activity of Ni/SiO2 for the deoxygenation of methyl laurate, and FeNi(0.25)/SiO2 with a Fe/Ni weight ratio of 0.25 showed the best activity. Moreover, the addition of Fe to Ni/SiO2 significantly promoted the hydrodeoxygenation pathway to produce more C12 hydrocarbon and suppressed the activity for C-C hydrogenolysis. The effect of Fe on the performance of Ni/SiO2 is ascribed the formation of the NiFe alloy particles, particularly with the Fe-enriched surface at low Fe content, and the existence of oxygen vacancies in Fe oxides. A mechanism is proposed to explain the promoting effect of Fe, which involves the synergism between iron sites with strong oxophilicity and nickel sites with high ability to activate hydrogen. Besides, the effect of reaction conditions and catalyst stability were also investigated.
- Yu, Xinbin,Chen, Jixiang,Ren, Tianyu
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p. 46427 - 46436
(2015/01/09)
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- Evaluation of cyclopentyl methyl ether (CPME) as a solvent for radical reactions
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We have explored the potential of cyclopentyl methyl ether (CPME) as a solvent for radical reactions. Hydrostannation, hydrosilylation, hydrothiolation, and tributyltin hydride mediated reductions were successfully carried out in CPME. GC-MS analysis indicated that CPME degraded into methyl pentanoate, cyclopentanone, 2-cyclopenten-1-ol, and cyclopentanol under thermal radical conditions, albeit only slightly. We also achieved radical-containing one-pot reactions in CPME as a demonstration of its applicability to multi-step reactions.
- Kobayashi, Shoji,Kuroda, Hiroyuki,Ohtsuka, Yuta,Kashihara, Takashi,Masuyama, Araki,Watanabe, Kiyoshi
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p. 2251 - 2259
(2013/03/29)
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- Radical-mediated intramolecular C-C bond formation and the deoxygenation of alcohols under solvent-free conditions with tributyl methyl ammonium hypophosphite
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A green, solvent-free protocol was developed for the radical-mediated intramolecular cyclization of haloacetals and the deoxygenation of S-methyl dithiocarbonates and cyclic thionocarbonate. This process uses tributyl methyl ammonium hypophosphite as a H-donor in the presence of triethylborane or t-butyl peroxide. This methodology provides eco-friendly reaction conditions.
- Lee, Eun Hwa,Cho, Dae Hyan,Satyender, Apuri,Jang, Doo Ok
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experimental part
p. 6927 - 6929
(2012/02/05)
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- Studies on partial hydrogenation of 1,5,9-cyclo-dodecatriene towards cyclo-dodecene
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The selective hydrogenation of 1,5,9-cis,trans,trans-cyclo-dodecatriene (1,5,9-ctt-CDT) towards cyclo-dodecene (CDE) depends strongly on the pressure of hydrogen, respectively the hydrogenation rate. High yields of CDE (>90%) can only be reached at extremely low hydrogen pressure. In order to elucidate this exceptional reaction performance the course of reaction has been studied for a wide range of hydrogen pressure, 0.01>pH2>2.5MPa, taking into consideration data of other research groups. The CDT hydrogenations were discontinuously carried out in liquid phase on Pd/Al2O3 at T = 353 K. The resulting hypothesis of this study is that the very low reaction rate at low pH2 is necessary in order to realize a dense surface coverage of 1,5,9-CDT and 1,5-cyclo-dodecadiene (CDD) isomers where these molecules show adsorption on Pd via two double bonds so that readsorption of formed CDE and subsequent hydrogenation to cyclo-dodecane (CDA) is hardly possible. On the whole this new hypothesis on the reaction course of CDT hydrogenation gives a sound and fully consistent view on this rather complicated reaction.
- Gaube,David,Sanchayan,Wuchter,Klein
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experimental part
p. 21 - 27
(2012/02/15)
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- Indium-catalyzed radical reductions of organic halides with hydrosilanes
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(Equation Presented) The In(OAc)3-catalyzed reaction of bromo- and iodoalkanes with PhSiH3 in THF at 70°C gave dehalogenated alkanes in good to high yields. In the presence of Et3B and air, the reduction proceeded smoothly at 30°C. When 2,6-lutidine and air were used as additives, the In(OAc)3-catalyzed system enabled an efficient reduction of simple and functionalized iodoalkanes in EtOH. Catalytic use of GaCl3 was found to be effective in the reduction of haloalkanes with poly(methylhydrosiloxane) (PMHS). These catalytic reductions probably involve a radical chain mechanism in which indium or gallium hydride species work as the actual reductants.
- Miura, Katsukiyo,Tomita, Mitsuru,Yamada, Yusuke,Hosomi, Akira
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p. 787 - 792
(2007/10/03)
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- Radical reactions in aqueous medium using (Me3Si)3SiH
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(Chemical Equation Presented) (Me3Si)3SiH was used as a successful reagent in a variety of radical-based transformations in water. The system comprising substrate, silane, and initiator (ACCN) mixed in aqueous medium at 100°C worked well for both hydrophilic and hydrophobic substrates, with the only variation that an amphiphilic thiol was also needed in case of the water-soluble compounds.
- Postigo, Al,Kopsov, Sergey,Ferreri, Carla,Chatgilialoglu, Chryssostomos
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p. 5159 - 5162
(2008/09/17)
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- Highly selective hydrogenation of multiple carbon-carbon bonds promoted by nickel(0) nanoparticles
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A new method for the highly stereoselective cis semihydrogenation of internal alkynes, semihydrogenation of terminal alkynes, reduction of dienes to alkenes, and reduction of alkynes and alkenes to alkanes is described based on in situ generated both Ni(0) nanoparticles and molecular hydrogen.
- Alonso, Francisco,Osante, I?aki,Yus, Miguel
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- 1,x-Elimination reactions: Extending the limits of a classical organic reaction
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α,ω)-Dibromo derivatives in ich the two terminal carbon atom are separated by an unsaturated spacer unit (ππ spacer") undergo 1,x-elimination reactions (with x = 6, 8, 10, and 14), using Mori's reagent (nBu3SnSiMe3/CsF). The resulting cumulenic intermediates cyclodimerize in a subsequent step yielding novel macrocyclic acetylenic and bridged aromatic compounds (cyclophanes). Thus 1,6-eliminations were carried out with dibromide 17 to yield 1,3,7,9-cyclododecatetrayne (20) and with benzylbromide 24 to provide cyclophanes 26 and 27. By 1,8-eliminations the 16-membered macrocycle 33 could be prepared from enediyne 31, the benzannelated 1,5-cyclooctadiyne 41 from dibromide 38, and a mixture of cyclophanes 45 and 46 from the precursor 43. 1,10-Eliminations were carried out successfully with dibromides 47, 50, and 53 yielding the corresponding unsaturated cyclophanes ("cyclophynes") 49, 52, and 55. The influence of the solvent on the cyclodimerization 47→49 was investigated, with acetonitrile providing the highest yields. The heterophanes 59a and b were obtained by 1,10-elimination of the precursor dibromides 57 a and b, and in an elimination experiment involving a 1:1 mixture of the dibromides 50 and 57 b the "mixed dimer" 60 was isolated, besides the homodimers 52 and 59 b. The method reached its limits with the 1,14-elimination of 68, 70, and 74 providing the cyclophanes 69, 71, and 75 in varying amounts. Two final debrominations with 76 and 77, which in principle could undergo 1,16- and 1,20-eliminations reactions, respectively, failed. The structures of the new cyclophanes 49, 50, 59 a, and 59 b were established by X-ray structural analysis; all other structure assignments rest on the usual spectroscopic and analytical data.
- Werner, Christian,Hopf, Henning,Dix, Ina,Bubenitschek, Peter,Jones, Peter G.
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p. 9462 - 9477
(2008/12/22)
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- Bimetallic Ru-Sn nanoparticle catalysts for the solvent-free selective hydrogenation of 1,5,9-cyclododecatriene to cyclododecene
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(Figure Presented) Tin(n)y catalysts: Bimetallic RuSn supported nanoparticle catalysts (see picture; Ru green, Sn blue, O red), prepared from the carbonyl-cluster precursors [Ru4 (μ4-SnPh) 2(μ-SnPh2)4-x(CO)12-x] (x = 0, 2, 3, 4) are shown to be active catalysts for the highly selective hydrogenation of 1,5,9-cyclododecatriene to cyclododecene under mild conditions.
- Adams, Richard D.,Boswell, Erin M.,Captain, Burjor,Hungria, Ana B.,Midgley, Paul A.,Raja, Robert,Thomas, John Meurig
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p. 8182 - 8185
(2008/09/18)
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- Polycyclic aromatic compounds-mediated electrochemical reduction of alkyl mesylates
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Electrochemical reduction of alkyl mesylates was successfully carried out by using an undivided cell equipped with a Pt cathode and an Mg anode in the presence of biphenyl and t-BuOH. The reaction could proceed efficiently under mild conditions to give the corresponding alkanes in moderate to good yields. This procedure could also be applicable to chemoselective reduction of mesylates having functional groups such as epoxide, olefin, acetal, hydroxy, or cyano groups. Copyright
- Senboku, Hisanori,Takahashi, Megumi,Fukuhara, Tsuyoshi,Hara, Shoji
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p. 228 - 229
(2008/02/04)
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- Palladium nanoparticles stabilized by alkylated polyethyleneimine as aqueous biphasic catalysts for the chemoselective stereocontrolled hydrogenation of alkenes
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Palladium nanoparticles were prepared, stabilized, and dispersed in water by alkylated branched polyethyleneimine. The palladium nanoparticles were effective aqueous biphasic catalysts for the chemoselective hydrogenation of alkenes with preferential reduction of less hindered double bonds, such as reduction of 3-methylcyclohexene in the presence of 1-methylcyclohexene and 1-octene in the presence of 2-methyl-2-heptene.
- Vasylyev, Maxym V.,Maayan, Galia,Hovav, Yonathan,Haimov, Adina,Neumann, Ronny
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p. 5445 - 5448
(2007/10/03)
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- Demonstration of a magnetic and catalytic Co@Pt nanoparticle as a dual-function nanoplatform
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Co@Pt nanoparticles as a bifunctional nanoplatform system for the hydrogenation of various unsaturated organic molecules under mild conditions and also for magnetic separation and recycling are demonstrated. The Royal Society of Chemistry 2006.
- Jun, Chul-Ho,Park, Young Jun,Yeon, Ye-Rim,Choi, Joon-Rak,Lee, Woo-Ram,Ko, Seung-Jin,Cheon, Jinwoo
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p. 1619 - 1621
(2008/02/08)
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- BF3·2CF3CH2OH (BF 3·2TFE), an efficient superacidic catalyst for some organic synthetic transformations
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BF3 · 2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid. The structure and properties of the 1:2 boron trifluoride-trifluoroethanol complex have been further studied using NMR (1H, 13C, 19F, 11B) and DFT calculations at the B3LYP/6- 311++G**//B3LYP/6-31G* level.
- Prakash, G. K. Surya,Mathew, Thomas,Marinez, Eric R.,Esteves, Pierre M.,Rasul, Golam,Olah, George A.
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p. 3952 - 3958
(2007/10/03)
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- Synthetic radical reactions using dibutylchlorogermane and dibutylethoxygermane as radical mediators
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In the presence of Et3B as radical initiator, dibutylchlorogermane (1a) and dibutylethoxygermane (1b) reacted with bromo- and iodoalkanes at room temperature to give the corresponding alkanes in high yields. Hydrogermane 1a was more reactive than 1b. However, 1b worked as a better radical mediator in intermolecular radical addition of haloalkanes to electron-deficient alkenes. Georg Thieme Verlag Stuttgart.
- Miura, Katsukiyo,Ootsuka, Kazunori,Hosomi, Akira
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p. 3151 - 3153
(2007/10/03)
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- Deoxygenation of alcohols employing water as the hydrogen atom source
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Trialkylboranes (BMe3, BEt3, and BBu3) have been shown to mediate reductive deoxygenation reactions of O-alkyl-S-methyl dithiocarbonates (methyl xanthates) in which water or deuterium oxide functions as the source of hydrogen or deuterium. This method has proven versatile with regard to substrate scope and is capable of providing protio- or deuterioalkane products in high yields with excellent levels of D-incorporation. Ab initio calculations suggest that the trialkylborane-water complex possesses an unusually low O-H bond dissociation energy (73 kcal/mol) and support a radical chain mechanism for this process. Taken together, this report provides evidence for fundamentally novel and previously overlooked modes of reactivity for water and trialkylboranes of wide ranging importance in both theoretical and applied investigations. Copyright
- Spiegel, David A.,Wiberg, Kenneth B.,Schacherer, Laura N.,Medeiros, Matthew R.,Wood, John L.
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p. 12513 - 12515
(2007/10/03)
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- Radical deoxygenation of alcohols and intermolecular carbon-carbon bond formation with surfactant-type radical chain carriers in water
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An efficient and mild method is developed for radical deoxygenation of alcohols and formation of carbon-carbon bonds in water without adding additives such as surfactants. The reaction was applied to synthesis of 2′,3′-didehydro-2′,3′-dideoxynucleosides that are potent anti-HIV agents. The reaction afforded environmentally benign reaction conditions.
- Cho, Dae Hyan,Jang, Doo Ok
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p. 1799 - 1802
(2007/10/03)
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- METHOD FOR PRODUCING CYCLODODECANONE
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The invention relates to a method for producing cyclododecanone by reacting cyclododecen with dinitrogen, especially a method comprising steps (I) and (II): (I) producing cyclododecen by partially hydrating cyclododecatriene; (II) reacting the cyclododecen obtained in step (I) with dinitrogen monoxide, thereby obtaining cyclododecanone.
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Page/Page column 27-28
(2008/06/13)
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- Diradical-promoted (n + 2 - 1) ring expansion: An efficient reaction for the synthesis of macrocyclic ketones
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(Chemical Equation Presented) A diradical-promoted (n + 2 - 1) ring expansion reaction based on vinyl side chain insertion (+2C) and decarbonylation (-1C) has been developed. Flash vacuum pyrolysis (FVP) of medium- and large-ring 2-trimethylsilyloxy-2-vinyl-cycloalkanones at 500-600°C affords the one-carbon ring-expanded cycloalkanones in good yields. Methyl groups on the vinyl moiety are transformed regiospecifically as corresponding α- and β-substituents, respectively. 2-Ethynyl precursor analogues react in a manner similar to give α,β-unsaturated cyclic ketones.
- Rueedi, Georg,Oberli, Matthias A.,Nagel, Matthias,Hansen, Hans-Jurgen
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p. 3179 - 3181
(2007/10/03)
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- PROCESS FOR PREPARATION OF CYCLODODECANONE
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In the process for producing a cyclododecanone by iscmerizing an epoxycyclododecane-containing starting material in the presence of an isomerization reaction catalyst containing lithium bromide and/or lithium iodide, in order to perform the reaction with high efficiency (high reaction rate) and high selectivity and stably produce a high-purity cyclododecanone in industry while maintaining a high-level reaction rate, the epoxycyclododecane-containing starting material is produced by contacting an epoxycyclododecadiene with hydrogen in the presence of a hydrogen-reduction catalyst and has a content of the hydroxyl group-containing cyclododecane compounds contained in the epoxycyclododecane-containing starting material controlled to 5 mol% or less.
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- Triethylborane-induced radical reactions with gallium- and indium hydrides
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A gallium hydride reagent, HGaCl2, was found to act as a radical mediator. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source. An indium hydride reagent, HInCl2, prepared from indium trichloride and diisobutylaluminum hydride also worked as a radical mediator. HInCl2 could reduce aryl iodides and bromides in the presence of Et3B as a radical initiator.
- Takami, Kazuaki,Mikami, Satoshi,Yorimitsu, Hideki,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 6627 - 6635
(2007/10/03)
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- The NiCl2-Li-Arene (cat.) Combination as Reducing System, Part 9: Catalytic Hydrogenation of Organic Compounds using the NiCl 2-Li-(Naphthalene or Polymer-Supported Naphthalene) (cat.) Combination
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The reaction of lithium powder, a catalytic amount of naphthalene or polymer-supported naphthalene, and anhydrous nickel(II) chloride, in THF at room temperature, generates a finely divided and very reactive nickel(0) which has been efficiently applied to the catalytic hydrogenation of different organic compounds such as alkenes, alkynes, carbonyl compounds, imines, organic halides, aromatic compounds, hydrazines, azoxy compounds, and N-oxides.
- Alonso, Francisco,Candela, Pablo,Gómez, Cecilia,Yus, Miguel
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p. 275 - 279
(2007/10/03)
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- Silylated cyclohexadienes as new radical chain reducing reagents: Preparative and mechanistic aspects
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Various silylated 1,4-cyclohexadienes are presented as superior tin hydride substitutes for the conduction of various radical chain reductions. Debrominations, deiodinations, and deselenations can be performed using these environmentally benign reagents. Furthermore, Barton - McCombie-type deoxygenations using silylated cyclohexadienes are described. Radical cyclizations, ring expansions, and Giesetype addition reactions with the new tin hydride substitutes are presented. The polymerization of styrene can be regulated using silylated cyclohexadienes. Rate constants for hydrogen atom abstraction from two 1-silyl-cyclohexadienes by primary C-radicals were determined. The effects of the cyclohexadiene substituents on the reaction outcomes are discussed. Finally, qualitative EPR experiments on silyl radical expulsion from silylated cyclohexadienyl radicals are presented.
- Studer, Armido,Amrein, Stephan,Schleth, Florian,Schulte, Tobias,Walton, John C.
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p. 5726 - 5733
(2007/10/03)
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- Radical deoxygenation of alcohols and vicinal diols with N-ethylpiperidine hypophosphite in water
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Radical deoxygenation of alcohols and vicinal diols with N-ethylpiperidine hypophosphite both in alcohols and in water is described. S-Methyl dithiocarbonate and bis-S-methyl dithiocarbonate of carbohydrates and nucleosides were deoxygenated efficiently under reaction conditions.
- Jang, Doo Ok,Cho, Dae Hyan
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p. 5921 - 5924
(2007/10/03)
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- Method of hydrogenating epoxidized C6—C12 cyclohydrocarbon compounds
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Epoxidized C6-C12cyclohydrocarbon compounds, for example, epoxidized C6-C12cycloalkanes, cycloalkenes and/or cycloalkadienes are converted to cycloalkanols, cycloalkanones and cycloalkanes by hydrogenating the epoxidized C6-C12cyclohydrocarbon compounds with hydrogen under a pressure of 0.1 to 5.4 MPa at a temperature of 100 to 280° C. in the presence of a catalyst containing at least one platinum group metal, for example, Pd or Ru.
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Example 8-10
(2008/06/13)
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- Deoxygenation of tertiary and secondary alcohols ROH by thiol-catalysed radical-chain redox decomposition of derivatives ROCH2X to give RH and XCHO
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Compounds of the type ROCH2X, in which the substituent X is an electron-donating alkoxy, aryl or amido group, undergo thiol-catalysed radical-chain decomposition to give RH and XCHO. This reaction has been applied for the deoxygenation of representative tertiary and secondary alcohols ROH under metal-free conditions that require no stoichiometric co-reactant. Of the derivatives investigated, methoxymethyl (MOM) ethers and 1-alkoxymethyl-pyrrolidin-2-ones (PYRM ethers) proved to be the most generally successful and typical conditions for the redox decomposition to give RH involve heating under reflux in octane solvent in the presence of a peroxide initiator and tri-tert-butoxysilanethiol [(ButO)3SiSH] as a protic polarity-reversal catalyst. Conversions to RH were negligible in the absence of thiol. Several different types of tertiary alcohol, including steroidal and carbohydrate examples, were deoxygenated as their MOM and PYRM ethers to give very good isolated yields of RH. Although the MOM and PYRM ethers derived from many types of secondary alcohol also afforded good yields of RH, the MOM ether of diacetone D-glucose gave the 3-deoxy sugar in poor yield and the yield from the corresponding PYRM ether was still only moderate.
- Dang, Hai-Shan,Roberts, Brian P.
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p. 1161 - 1170
(2007/10/03)
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- Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2
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(formula presented) Agallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.
- Mikami, Satoshi,Fujita, Kazuya,Nakamura, Tomoaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
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p. 1853 - 1855
(2007/10/03)
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- Reduction of organic halides with tri-2-furylgermane: Stoichiometric and catalytic reduction
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Tri-2-furylgermane proved to be an effective reagent for the radical reduction of organic halides. Treatment of 1-bromododecane with tri-2-furylgermane in THF at 25 °C in the presence of a catalytic amount of triethylborane afforded dodecane almost quantitatively. Radical cyclization of 2-iodoethanal allyl acetal afforded five-membered products under the same reaction conditions. These reactions proceeded with NaBH4 in the presence of a catalytic amount of germanium hydride. The reaction took place in water as well as in THF to give the corresponding reduced compounds in good yields.
- Nakamura,Yorimitsu,Shinokubo,Oshima
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p. 747 - 752
(2007/10/03)
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- Solvent-free, low-temperature, selective hydrogenation of polyenes using a bimetallic nanoparticle Ru-Sn catalyst
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The point of attachment of bimetallic Ru6Sn particles which are anchored to the pore walls of a highly dispersed high-area mesoporous silica is found to be the tin atom, as indicated by in situ and ex situ measurements. This catalyst displays high activity for the low-temperature, selective hydrogenation of cyclic polyenes under solvent-free conditions (see scheme).
- Hermans, Sophie,Raja, Robert,Thomas, John M.,Johnson, Brian F. G.,Sankar, Gopinathan,Gleeson, David
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p. 1211 - 1215
(2007/10/03)
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- Radical deoxygenation of alcohols via their trifluoroacetate derivatives with diphenylsilane
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Trifluoroacetate derivatives of alcohols can be used as precursors for the radical deoxygenation of alcohols with diphenylsilane. The reaction afforded high isolated yields of the deoxygenated products and neutral reaction conditions.
- Jang, Doo Ok,Kim, Joonggon,Cho, Dae Hyan,Chung, Chan-Moon
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p. 1073 - 1075
(2007/10/03)
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