- Sequential Ketene Generation from Dioxane-4,6-dione-keto-dioxinones for the Synthesis of Terpenoid Resorcylates
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Trapping of the ketene generated from the thermolysis of 2-methyl-2-phenyl-1,3-dioxane-4,6-dione-keto-dioxinone at 50°C with primary, secondary, or tertiary alcohols gave the corresponding dioxinone β-keto-esters in good yield under neutral conditions. Th
- Elliott, Daniel C.,Ma, Tsz-Kan,Selmani, Aymane,Cookson, Rosa,Parsons, Philip J.,Barrett, Anthony G. M.
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- CANNABINOID DERIVATIVES
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The present invention provides cannabinoid derivatives, a pharmaceutical composition comprising said derivative and a method of using said derivatives in treating or preventing a disease associated with cannabinoid receptors. The claimed cannabinoid derivatives are described by the following formula or an enantiomer, diastereomer, racemate, tautomer, or metabolite thereof, or a pharmaceutically acceptable salt, solvate or hydrate of the compound.
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Paragraph 0136
(2021/01/23)
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- CANNABINOID DERIVATIVES
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This disclosure relates generally to cannabinoid derivatives of the following structure, pharmaceutical compositions comprising them, and methods of treating or preventing diseases associated with cannabinoid receptors using said compounds.
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Paragraph 0133
(2021/02/12)
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- Enantioselective Cu-catalyzed 1,4-additions of organozinc and Grignard reagents to enones: Exceptional performance of the hydrido-phosphite-ligand BIFOP-H
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Enantioselective Cu(I),(II)-(i.e. CuCl, CuCl2, Cu(OTf)2)-catalyzed 1,4-additions of organozinc, i.e. (Et, Me)2Zn, and Grignard reagents, i.e. (Et, Me)MgBr, to chalcone, cyclohexenone and chromone are studied, employing fencholate-based phosphorus ligands, e.g. biphenyl-2,2′-bisfenchyl hydrido phosphite = BIFOP-H. The CuCl·BIFOP-H-catalyzed 1,4-addition of Et2Zn to chalcone yields up to 93% and 99% ee, exceeding established BINOL- and TADDOL-based phosphoramidite ligands. Remarkably, CuCl performs better in 1,4-additions to chalcone (CuCl: 76% ee; Cu(OTf)2: 49% ee; CuCl2: 42% ee) while Cu(OTf)2 performs better in 1,4-additions to cyclohexenone (Cu(OTf)2: 65% ee; CuCl: 20% ee). The computation of the reaction pathway is done for the CuI-catalyzed 1,4-addition to chalcone (CuII will be in situ reduced to CuI by a reagent, TPSS-D3(BJ)/def2-TZVP//B3LYP-D3(BJ)/def2-SVP) for six different model ligands, i.e. (MeO)2P-X (X = H, F, Me, OMe, NMe2 and PMe3). Origins of enantioselectivities are analyzed (M06-2X-D3/def2-TZVP//B3LYP-D3(BJ)/def2-SVP) for transition structures of the 1,4-methylation of chalcone with the Cu·BIFOP-H catalyst and explain the experimentally observed (R)-enantiomer's preference.
- Brüllingen, Eric,Neud?rfl, J?rg-Martin,Goldfuss, Bernd
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supporting information
p. 4787 - 4799
(2019/03/26)
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- Guanidine–Copper Complex Catalyzed Allylic Borylation for the Enantioconvergent Synthesis of Tertiary Cyclic Allylboronates
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An enantioconvergent synthesis of chiral cyclic allylboronates from racemic allylic bromides was achieved by using a guanidine–copper catalyst. The allylboronates were obtained with high γ/α regioselectivities (up to 99:1) and enantioselectivities (up to 99 % ee), and could be further transformed into diverse functionalized allylic compounds without erosion of optical purity. Experimental and DFT mechanistic studies support an SN2′ borylation process catalyzed by a monodentate guanidine–copper(I) complex that proceeds through a special direct enantioconvergent transformation mechanism.
- Ge, Yicen,Cui, Xi-Yang,Tan, Siu Min,Jiang, Huan,Ren, Jingyun,Lee, Nicholas,Lee, Richmond,Tan, Choon-Hong
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supporting information
p. 2382 - 2386
(2019/02/01)
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- Lewis acids promoted 3 + 2 cycloaddition of oxaziridines and cyclic allylic alcohols through carbonyl imine intermediates
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Syntheses of isoxazolidines through the carbonyl imine intermediates are currently limited to monosubstituted olefin substrates. Herein, we reported syntheses of novel bicyclic isoxazolidine-containing compounds through 1,3-dipolar cycloaddition reactions
- Zhao, Erbao,Zhou, Feilong,Zhao, Yujun
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p. 4282 - 4293
(2019/04/30)
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- Aerobic oxidation of the C-H bond under ambient conditions using highly dispersed Co over highly porous N-doped carbon
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Highly dispersed Co sites in highly porous N-doped carbon (Co-NC) were synthesized by high-temperature pyrolysis of Zn/Co bimetallic zeolitic imidazolate framework-8 (CoxZn100-x-ZIF). Wide characterization indicated that the pyrolysis atmosphere and temperature play crucial roles in the metal dispersion and pore structure of the resulting materials. A hydrogen treatment at elevated temperatures is found to favour the Zn volatilization and restrict the pore shrinkage of the ZIF precursor, thus yielding efficient catalysts with highly dispersed Co, a high surface area (1090 m2 g-1) and pore volume (0.89 cm3 g-1). When used as a catalyst for aerobic oxidation of ethylbenzene (EB), Co1Zn99-ZIF-800-H2 contributes to 98.9% EB conversion and 93.1% ketone selectivity under mild conditions (60 °C, 1 atm O2), which is 41.3 times more active in comparison to the ZIF-67-derived Co catalyst. Co-NC is stable and could be reused four times without obvious deactivation. This catalyst displays good chemoselectivity to the corresponding ketones when using a broad scope of hydrocarbon compounds.
- Nie, Renfeng,Chen, Jingwen,Chen, Minda,Qi, Zhiyuan,Goh, Tian-Wei,Ma, Tao,Zhou, Lin,Pei, Yuchen,Huang, Wenyu
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p. 1461 - 1466
(2019/03/26)
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- Chemo-Enzymatic Oxidative Rearrangement of Tertiary Allylic Alcohols: Synthetic Application and Integration into a Cascade Process
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A chemo-enzymatic catalytic system, comprised of Bobbitt's salt and laccase from Trametes versicolor, allowed the [1,3]-oxidative rearrangement of endocyclic allylic tertiary alcohols into the corresponding enones under an Oxygen atmosphere in aqueous media. The yields were in most cases quantitative, especially for the cyclopent-2-en-1-ol or the cyclohex-2-en-1-ol substrates without an electron withdrawing group (EWG) on the side chain. Transpositions of macrocyclic alkenols or tertiary alcohols bearing an EWG on the side chain were instead carried out in acetonitrile by using an immobilized laccase preparation. Dehydro-Jasmone, dehydro-Hedione, dehydro-Muscone and other fragrance precursors were directly prepared with this procedure, while a synthetic route was developed to easily transform a cyclopentenone derivative into trans-Magnolione and dehydro-Magnolione. The rearrangement of exocyclic allylic alcohols was tested as well, and a dynamic kinetic resolution was observed: α,β-unsaturated ketones with (E)-configuration and a high diastereomeric excess were synthesized. Finally, the 2,2,6,6-tetramethyl-1-piperidinium tetrafluoroborate (TEMPO+BF4?)/laccase catalysed oxidative rearrangement was combined with the ene-reductase/alcohol dehydrogenase cascade process in a one-pot three-step synthesis of cis or trans 3-methylcyclohexan-1-ol, in both cases with a high optical purity. (Figure presented.).
- Brenna, Elisabetta,Crotti, Michele,De Pieri, Matteo,Gatti, Francesco G.,Manenti, Gabriele,Monti, Daniela
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supporting information
p. 3677 - 3686
(2018/06/04)
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- Lithium-Catalyzed Thiol Alkylation with Tertiary and Secondary Alcohols: Synthesis of 3-Sulfanyl-Oxetanes as Bioisosteres
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3-Sulfanyl-oxetanes are presented as promising novel bioisosteric replacements for thioesters or benzyl sulfides. From oxetan-3-ols, a mild and inexpensive Li catalyst enables chemoselective C?OH activation and thiol alkylation. Oxetane sulfides are formed from various thiols providing novel motifs in new chemical space and specifically as bioisosteres for thioesters due to their similar shape and electronic properties. Under the same conditions, various π-activated secondary and tertiary alcohols are also successful. Derivatization of the oxetane sulfide linker provides further novel oxetane classes and building blocks. Comparisons of key physicochemical properties of the oxetane compounds to selected carbonyl and methylene analogues indicate that these motifs are suitable for incorporation into drug discovery efforts.
- Croft, Rosemary A.,Mousseau, James J.,Choi, Chulho,Bull, James A.
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supporting information
p. 818 - 821
(2017/12/26)
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- (Guanidine)copper Complex-Catalyzed Enantioselective Dynamic Kinetic Allylic Alkynylation under Biphasic Condition
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Highly enantioselective allylic alkynylation of racemic bromides under biphasic condition is furnished in this report. This approach employs functionalized terminal alkynes as pro-nucleophiles and provides 6- and 7-membered cyclic 1,4-enynes with high yields and excellent enantioselectivities (up to 96% ee) under mild conditions. Enantioretentive derivatizations highlight the synthetic utility of this transformation. Cold-spray ionization mass spectrometry (CSI-MS) and X-ray crystallography were used to identify some catalytic intermediates, which include guanidinium cuprate ion pairs and a copper-alkynide complex. A linear correlation between the enantiopurity of the catalyst and reaction product indicates the presence of a copper complex bearing a single guanidine ligand at the enantio-determining step. Further experimental and computational studies supported that the alkynylation of allylic bromide underwent an anti-SN2′ pathway catalyzed by nucleophilic cuprate species. Moreover, metal-assisted racemization of allylic bromide allowed the reaction to proceed in a dynamic kinetic fashion to afford the major enantiomer in high yield.
- Cui, Xi-Yang,Ge, Yicen,Tan, Siu Min,Jiang, Huan,Tan, Davin,Lu, Yunpeng,Lee, Richmond,Tan, Choon-Hong
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supporting information
p. 8448 - 8455
(2018/06/22)
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- Iron(III) chloride-benzotriazole adducts with trigonal bipyramidal geometry: Spectroscopic, structural and catalytic studies
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The reactions of FeCl3 with benzotriazole (btaH), 1-methylbenzotriazole (Mebta), 5,6-dimethylbenzotriazole (5,6Me2btaH) and 5-chlorobenzotriazole (5ClbtaH) were studied in non-polar solvents. The new solid complexes [FeCl3(btaH)2] (1), [FeCl 3(Mebta)2] (2), [FeCl3(5,6Me 2btaH)2] (3) and [FeCl3(5ClbtaH) 2]·2(5ClbtaH) (4) have been isolated. The structures of the complexes have been determined by single-crystal, X-ray crystallography. The structures of 1-4 consist of mononuclear, high-spin 5-coordinate molecules; in addition, the crystal structure of 4 contains two lattice 5ClbtaH molecules per [FeCl3(5ClbtaH)2] unit. The coordinated benzotriazole molecules behave as monodentate ligands with their ligated atom being the nitrogen of the position 3 of the azole ring. The geometry at iron(III) is trigonal bipyramidal with the chlorido ligands occupying the equatorial sites. The crystal structures of the complexes are stabilized by stacking interactions and H bonds (for 1, 3 and 4 only). The new complexes were characterized by elemental analyses, magnetic susceptibilities at room temperature and spectroscopic (IR, far-IR, solid-state electronic UV/VIS/near-IR, 57Fe-Mo?ssbauer, EPR only for complex 4) methods. All data are discussed in terms of the nature of bonding and the known structures. Complexes 1, 2 and 4 have been tested as homogeneous (MeCN) oxidation catalysts in the presence of the "green" H2O2 oxidant; they display moderate to high catalytic activity in the oxidation of several alkenes, cyclohexane and n-hexane, which is described in detail.
- Anastasiadis, Nikolaos C.,Bilis, George,Plakatouras, John C.,Raptopoulou, Catherine P.,Psycharis, Vassilis,Beavers, Christine,Teat, Simon J.,Louloudi, Maria,Perlepes, Spyros P.
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p. 189 - 202
(2013/10/08)
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- Stereo- and regioselectivity in the P450-catalyzed oxidative tandem difunctionalization of 1-methylcyclohexene
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The selective partial oxidation of small non-functionalized molecules using biocatalysis based on P450 monooxygenases is known to be difficult due to the expected poor regio- and stereoselectivity, but in this study it was nevertheless attempted. 1-Methyl
- Roiban, Gheorghe-Doru,Agudo, Rubén,Reetz, Manfred T.
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p. 5306 - 5311
(2013/07/05)
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- Diastereodivergent hydroxyfluorination of cyclic and acyclic allylic amines: Synthesis of 4-deoxy-4-fluorophytosphingosines
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A diastereodivergent hydroxyfluorination protocol enabling the direct conversion of some conformationally biased allylic amines to the corresponding diastereoisomeric amino fluorohydrins has been developed. Sequential treatment of a conformationally biased allylic amine with 2 equiv of HBF 4·OEt2 followed by m-CPBA promotes epoxidation of the olefin on the face proximal to the amino group under hydrogen-bonded direction from the in situ formed ammonium ion. Regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety) then occurs in situ to give the corresponding amino fluorohydrin. Alternatively, an analogous reaction using 20 equiv of HBF4·OEt2 results in preferential epoxidation of the opposite face of the olefin, which is followed by regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety). The synthetic utility of this methodology is demonstrated via its application to a synthesis of 4-deoxy-4-fluoro-l-xylo- phytosphingosine and 4-deoxy-4-fluoro-l-lyxo-phytosphingosine, each in five steps from Garner's aldehyde.
- Cresswell, Alexander J.,Davies, Stephen G.,Lee, James A.,Morris, Melloney J.,Roberts, Paul M.,Thomson, James E.
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p. 7262 - 7281
(2012/10/30)
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- Highly regioselective control of 1,2-addition of organolithiums to α,β-unsaturated compounds promoted by lithium bromide in 2-methyltetrahydrofuran: A facile and eco-friendly access to allylic alcohols and amines
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Very high regioselective 1,2-addition of organolithiums to α,α-unsaturated carbonyl-like compounds (ketones, aldehydes, and imines) in the presence of LiBr was achieved by carrying out reactions in the sustainable solvent 2-methyltetrahydrofuran. Excellent yields (in isolated product) of allylic alcohols and allylic amines were recovered under a simple experimental procedure at 0 °C.
- Pace, Vittorio,Castoldi, Laura,Hoyos, Pilar,Sinisterra, José Vicente,Pregnolato, Massimo,Sánchez-Montero, Ma. José
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supporting information; experimental part
p. 2670 - 2675
(2011/04/23)
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- Transition-metal chloride mediated addition reaction of diorganomagnesium to easily enolizable ketones
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An alkylation to an easily enolizable ketone, such as β-tetralone, is difficult to perform with Grignard reagent (RMgX) or with diorganomagnesium (R2Mg), because a deprotonation to form a magnesium enolate occurs predominantly. To avoid the prior enolization, a complex reagent of a transition-metal salt and R2Mg was examined: A combination of R 2Mg with iron(II) chloride (FeCl2) or ytterbium(III) chloride (YbCl3) gave a complex reagent that can realize a nucleophilic reaction to β-tetralone prior to the enolization. A combination of RMgX with these metal salts is inferior to a combination of R2Mg with them to obtain the nucleophilic complex reagent.
- Sada, Mutsumi,Matsubara, Seijiro
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experimental part
p. 2612 - 2616
(2011/04/25)
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- Hydrocarbon oxidation by homogeneous and heterogeneous non-heme iron (III) catalysts with H2O2
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Homogeneous (LFeIII) and heterogeneous (LFe III·SiO2) [L = 3-{2-[2-(3-hydroxy-1,3-diphenyl- allylideneamino)-ethylamino]-ethylimino}-1,3-diphenyl-propen-1-ol] catalysts have been synthesized and evaluated catalytically. In CH3CN, both the homogeneous and heterogeneous catalysts were efficient in alkene oxidations. Cyclohexane oxidation provides total yield of 12.1% and 7.3% with an alcohol/ketone (A/K) ratio of 1.75 and 1.60 by the LFeIII and the LFeIII·SiO2 catalysts respectively. UV-vis kinetic data suggest formation of LFeIII-OOH species. EPR data show that in the presence of CH3CN, low-spin FeIII (S = 1/2) centers are formed, which are responsible for the catalytic activity. The heterogeneous LFe·SiO2 catalyst, tested up to 5 re-uses, shows a total yield loss ~4% per use, providing the same distribution of oxidation products.
- Bilis,Christoforidis,Deligiannakis,Louloudi
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scheme or table
p. 101 - 106
(2011/01/12)
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- Enhancement of the photoinduced oxidation activity of a ruthenium(II) complex anchored on silica-coated silver nanoparticles by localized surface plasmon resonance
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Plasmonic photocatalyst: Anchoring the dye [Ru(bpy)3] 2+ (bpy=2,2-bipyridine) on the surface of Ag nanoparticles coated with a thin SiO2 layer (see picture) afforded a photocatalyst whose phosphorescence emission and photoinduced oxidation activity in the selective liquid-phase oxidation of styrene are efficiently enhanced through interaction with the localized surface plasmon resonance of the core Ag nanoparticles.
- Mori, Kohsuke,Kawashima, Masayoshi,Che, Michel,Yamashita, Hiromi
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scheme or table
p. 8598 - 8601
(2011/01/09)
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- Mild two-step process for the transition-metal-free synthesis of carbon-carbon bonds from allylic alcohols/ethers and grignard reagents
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Chemical Equation Represented A mild two-step process for the regioselective, transition-metal-free preparation of carbon-carbon bonds from allylic alcohols/ethers and Grignard reagents is described. This process obviates the need for the harsh deprotecti
- Han, Xinping,Zhang, Yanhua,Wu, Jimmy
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supporting information; experimental part
p. 4104 - 4106
(2010/05/15)
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- Copper-catalyzed asymmetric conjugate addition with Grignard reagents and SimplePhos ligands
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Herein we report the copper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic and acyclic enones, with SimplePhos as chiral ligands. A variety of Grignard reagents can be added to a range of cyclic and acyclic enones, with moderate to good enantioselectivities (ee's up to 86%).
- Palais, Laetitia,Alexakis, Alexandre
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experimental part
p. 2866 - 2870
(2010/04/05)
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- Stereoselective aziridination of cyclic allylic alcohols using chloramine-T
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The stereoselective aziridination of a range of cyclic allylic alcohols using two different chloramine salts (4-MeC6H4SO 2NClNa, TsNClNa and t-BuSO2NClNa, BusNClNa) has been explored. The stereoselectivity of these reactions was highly dependent on the structure of the allylic alcohol and the chloramine salt. Generally, mixtures of cis- and trans-hydroxy aziridines were obtained, in which the major diastereomer was the cis-hydroxy aziridine, whilst complete cis- diastereoselectivity was observed in the aziridination of 1,3-disubstituted allylic alcohols. In each case studied, aziridination using BusNClNa gave higher cis-stereoselectivity than that observed for the same reaction using TsNClNa. Unexpectedly, application of the aziridination conditions to 1-substituted cyclopen-2-en-1-ols did not generate the aziridines. Instead, epoxy sulfonamides were obtained.
- Coote, Susannah C.,O'Brien, Peter,Whitwood, Adrian C.
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supporting information; experimental part
p. 4299 - 4314
(2009/02/07)
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- Glycol-modified molybdate catalysts for efficient singlet oxygen generation from hydrogen peroxide
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Pretreatment of molybdate-exchanged layered double hydroxides in polyalcohols such as ethylene glycol affords heterogeneous catalysts showing largely improved oxidant efficiency compared to the unmodified materials. The Royal Society of Chemistry.
- Wahlen, Joos,De Vos, Dirk,Jary, Walther,Alsters, Paul,Jacobs, Pierre
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p. 2333 - 2335
(2008/02/11)
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- Direct coupling reaction between alcohols and silyl compounds: Enhancement of Lewis acidity of Me3SiBr using InCl3
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The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the 13C NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by 29Si NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.
- Saito, Takahiro,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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p. 8516 - 8522
(2007/10/03)
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- Confined space-controlled hydroperoxidation of trisubstituted alkenes adsorbed on pentasil zeolites
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Photosensitized oxidation of trialkylalkenes 2-methyl-2-pentene (1), 1-methylcyclohexene (2), trans-3-methyl-2-pentene (3), cis-3-methyl-2-pentene (4), and 2-methyl-2-butene (5) included in the internal framework of Na-ZSM-5 zeolites was investigated. The zeolite samples having adsorbed the alkenes were suspended in isooctane, and the sensitizer, tetraphenylporphyrin (TPP), was dissolved in the solution. Singlet oxygen produced in the solution diffused into the internal framework of the zeolites and reacted with alkenes. For all the substrates studied, the ene-type allylic hydroperoxides were obtained in a highly regioselective manner. The regiochemistry for 1-4 in favor of the allylic hydrogen abstraction from the largest substituents is in contrast to their photooxidation within the dye-supported zeolite Na-Y, where the secondary hydroperoxides are preferentially produced. The tight confinement of the alkenes within the narrow channels of the ZSM-5 zeolites is likely to be responsible for this selectivity.
- Chen, Yu-Zhe,Wu, Li-Zhu,Zhang, Li-Ping,Tung, Chen-Ho
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p. 4676 - 4681
(2007/10/03)
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- Highly regioselective and diastereoselective epoxidation of allylic amines with Oxone
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Allylic amines (as their protonated ammonium salts) can be epoxidised with high syn diastereoselectivity and regioselectivity at the proximal alkene in substrates with several double bonds using Oxone. The protonated ammonium cation activates the Oxone by
- Aggarwal, Varinder K.,Fang, Guang Yu
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p. 3448 - 3450
(2007/10/03)
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- Effect of InCl3 on the addition of Grignard reagents to α,β-unsaturated carbonyl compounds
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Control of 1,2- versus 1,4-addition of organometallic reagents to enones remains a long-standing problem. There is still no satisfactory 1,2-directing agent comparable to the 1,4-directing effect of copper salts. We report that the presence of just 5 mol% indium(III) chloride can significantly alter the amount of 1,2-product formed in these reactions.
- Kelly, Brian G.,Gilheany, Declan G.
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p. 887 - 890
(2007/10/03)
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- Use of cyclic allylic bromides in the zinc-mediated aqueous Barbier-Grignard reaction
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The zinc-mediated aqueous Barbier-Grignard reaction of cyclic allylic bromide substrates with various aldehydes and ketones to afford homoallylic alcohols was investigated. Aromatic aldehydes and ketones afforded adducts in good yields (66-90%) and with good diastereoselectivities. Non-aromatic aldehydes also reacted well under these conditions, but only poor yields were obtained with non-aromatic ketones. Regioselectivity was high when some substituted cyclic allylic bromides were investigated.
- Breton, Gary W.,Shugart, John H.,Hughey, Christine A.,Conrad, Brian P.,Perala, Suzanne M.
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p. 655 - 662
(2007/10/03)
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- 1,4-Addition of diorganozincs to α,β-unsaturated ketones catalyzed by a copper(I)-sulfonamide combined system
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A mixture of CuCN and N-benzylbenzenesulfonamide catalyzes the 1,4- addition of dialkylzincs or diarylzincs (Cu: Zn = 1: 200 to 1: 10000) to α,β-unsaturated ketones to give, after aqueous workup, the corresponding β-substituted ketones in nearly quantitative yields. A range of cyclic enones having s-cis or s-trans geometries as well as conformationally flexible acyclic enones are usable as substrates. The ethyl group migrates more readily than the methyl and phenyl groups. CuOTf, CuO-t-C4H9, and mesitylcopper can be used in place of CuCN. The in situ-formed alkylzinc enolate, prior to aqueous workup, further undergoes an aldol reaction with aldehydes or Pd(0)-assisted coupling with allyl acetate, resulting in regio- controlled, vicinal carbacondensation products. A catalytic cycle is proposed on the basis of a kinetic study and a structural analysis of the zinc enolate product by NMR and molecular weight measurements.
- Kitamura, Masato,Miki, Takashi,Nakano, Keiji,Noyori, Ryoji
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p. 999 - 1014
(2007/10/03)
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- Asymmetric synthesis of (S)-1-methyl-2-cyclohexen-1-ol, a constituent of the aggregation pheromone of Dendroctonus pseudotsugae
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1-Methyl-2-cyclohexen-1-ol has been prepared by a three step synthesis from 1-methylcyclohexene, in greater than 94% e.e., via a 'merged substitution-elimination reaction' between NaSePh and 2-methyl-2- hydroxycyclohexyl p-toluenesulphonate. (C) 2000 Elsevier Science Ltd.
- Hamon, David P. G.,Tuck, Kellie L.
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p. 4829 - 4835
(2007/10/03)
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- Role of Amine Modifiers in the Epoxidation of Allylic Alcohols with a TiO2-SiO2 Aerogel
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A detailed study of the epoxidation of 3-methyl-2-cyclohexen-1-ol with tert-butylhydroperoxide revealed that the poor performance of a 20 wt% TiO2-80 wt% SiO2 aerogel was due to nonoxidative consumption of the allylic alcohol. Epoxide selectivities could be improved remarkably and acid-catalyzed side reactions suppressed by addition of small amounts of aliphatic, cycloaliphatic, or aromatic amines. The best modifier was N, N-dimethylbutylamine. Amine (1 mol%) enhanced the epoxide selectivities, related to the reactant or peroxide, from 3 to 99% and 35 to 100%, respectively. Kinetic investigations uncovered how the chemical structure and the amount of various amines influence the complex network of redox- and acid-catalyzed reactions during allylic alcohol epoxidations. The stability of amines was studied under oxidizing reaction conditions. The method of amine addition was applied also to the epoxidation of other linear and cyclic allylic alcohols and 2-hexene. The scope of this method seems to be limited to epoxidation of allylic alcohols. A model for the interaction of allylic alcohol, amine, and peroxide with the Ti active site is proposed, which can interpret the enhanced selectivity and suppressed activity in the presence of amines or other bases.
- Dusi, Marco,Mallat, Tamas,Baiker, Alfons
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p. 191 - 201
(2007/10/03)
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- Beryllium dichloride: Efficient promoter for the addition of organolithiums and organomagnesiums to cyclohexen-2-one
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Organoberyllium compounds, generated by transmetallation from Grignard and organolithium reagents react with 2-cyclohexenone to give predominantly the adducts resulting from conjugated addition. The chemoselectivity of this reaction was found to be highly dependent upon the nature of organic moiety and of the conditions used.
- Krief, Alain,De Vos, Marie Joelle,De Lombart, Stephane,Bosret, Jean,Couty, Francois
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p. 6295 - 6298
(2007/10/03)
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- Ultrasound Assisted Preparation of Organocerium Reagents
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Sonication of anhydrous CeCl3 in tetrahydrofuran facilitates rapid preparation of organocerium reagents.
- Greeves, Nicholas,Lyford, Lisa
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p. 4759 - 4760
(2007/10/02)
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- Initiated tert-Butyl Hydroperoxide-loaded Low-temperature Autoxidation of Alkenes: Alternative Hydroperoxide Syntheses and the Preparation of a Complete Set of Reference Material
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A complete set of characterization data for the allylic hydroperoxides prepared from 1-methylcyclohexene and the isomeric 4-methyloct-4-enes is presented.The data relies upon the preparation of allylic hydroperoxides by tert-butyl hydroperoxide-loaded autoxidations, singlet-ene oxidations and nucleophilic substitution reactions.Appropriate allylic alcohols and relevant scission products have been prepared to support the assignments given.
- Courtneidge, John L.,Bush, Melanie,Loh, Lay-See
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p. 1539 - 1548
(2007/10/02)
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- On the conjugate addition of tetraorganothallium ate complexes
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Tetraorganothallium ate complexes have been prepared and reacted with enones to afford either the [1,2] or [1,4] addition product. Mixed ate complexes display high levels of chemoselectivity in the transfer of one of their ligands.
- Marko,Rebiere
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p. 1763 - 1766
(2007/10/02)
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- Pheromone formulation for attracting spruce beetles
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Novel compositions and methods for the attraction of spruce beetles Dendroctonus rufipennis are provided. The compositions are comprised of both insect and tree-produced semiochemicals alone or in combination to attract populations of spruce beetles. The
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- Mechanism of the Grignard Adddition Reaction. XVI. Homolytic and Concerted Mechanisms in the Reaction of α,β-Unsatureted Carbonyl Compounds with Grignard Reagents
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Kinetic measurements have shown that the addition of Grignard reagents to α,β-unsaturated carbonyl compounds takes place either by a concerted mechanism or by a homolytic mechanism.Phenylmagnesium bromide, which is incapable of homolysis, reacts rapidly in a 1,4-fashion if an s-cis conformation exists between the C=C and the C=O bonds, but only 1,2-addition takes place if the conformation is s-trans.tert-Butylmagnesium bromide is unsuited to the concerted reaction, but 1,4-addition takes place via homolysis.Primary and secondary Grignard reagents, like phenyl, react rapidly in a concerted manner with s-cis substrates, but unlike phenyl, these Grignard reagents may, with s-trans substrates, produce some 1,4-adduct via the homolytic mechanism.
- Holm, Torkil
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p. 925 - 929
(2007/10/02)
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- SELEKTIVE KOHLENSTOFF-KOHLENSTOFF-VERKNUEPFUNGEN MIT NUCLEOPHILEN THERMOLABILEN METHYLCOBALT-REAGENZIEN
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Nonstabilized Co(II) methyl derivatives (MeCoCl, Me2Co, Me3CoLi, Me4CoLi2) are readily accessible in solution (THF, Et2O) by reaction of MeLi with CoCl2 at -78 deg C to -60 deg C.For checking the transmetallation process the "β-bromostyrene-ketone-test" is especially favorable.Characteristic features of the reactivity of the Co-reagents: High efficiency in the cross coupling with trans-β-bromo-styrene, high aldehyde-vs.-ketone selectivity in Et2O, methylation of 2-cyclohexenone mainly in β-position, the ate-complexes methylate carboxylic esters, but not tertiary carboxylic amides.
- Kauffmann, Thomas,Hopp, Gudrun,Laarmann, Barbara,Stegemann, Dieter,Wingbermuehle, Dorothea
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p. 511 - 514
(2007/10/02)
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- KONJUGIERTE ADDITION VON ALKYLDERIVATEN DER SPAETEN UEBERGANGSMETALLE Ag, Pd, Rh, Ru, Co UND Fe AN 2-CYCLOHEXENON
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In situ prepared alkyl derivatives of the 4d metals Ag, Rh (Alk = Me, n-Bu), Pd, Ru (Alk = Me) alkylate 2-cyclohexenone (1) exclusively or preferently in β-position to the keto group.The same was observed by applying Me2Fe, Me3FeLi or the hetero-ate complexes Me2(t-BuO)2FeLi2 and Me2(t-BuO)2CoLi2, whereas Me4FeLi2 methylates 1 at the keto group.
- Kauffmann, Thomas,Huelsduenker, Achim,Menges, Detlef,Nienaber, Hubert,Rethmeier, Lutz,et al.
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p. 1553 - 1556
(2007/10/02)
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- Oxygen Quenching of Electronically Excited Hexanuclear Molybdenum and Tungsten Halide Clusters
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Quenching of the electronically excited Y6(2-) (M = Mo(II), W(II), X,Y = Cl,Br,I) ions by molecular oxygen has been investigated.Stern- Volmer analysis of emission intensity and lifetime data reveals that the rate constants for oxygen quenching of the Y6(2-) ions are similar (kqobs = 8.1(37) * 1E7 M-1 s-1) with the exception of the Y6(2-) clusters, which exhibit significantly greater quenching rates (kqobs = 2.1(5) * 1E9 M-1 s-1).Photosensitized oxidation of 1-methylcyclohexene and 1,2-dimethylcyclohexene by all Y6(2-) clusters yields products expected for the reaction of the olefins with singlet oxygen.No evidence of radical autooxidation products were detected.However, the measured quantum yields for the photooxidation of 2,3-diphenyl-p-dioxene by only the Y6(2-) (M = no W; X = no I) clusters are in agreement with the values calculated from a kinetic scheme involving the exclusive production of singlet oxygen by direct energy transfer; observed quantum yields of Y6(2-) -photosensitized reactions are not consistent with this scheme.One explanation for the enhanced oxygen quenching rates of the Y6(2-) excited states (Y6(2-)(excit)) and anomalous observed quantum yields is the contribution of an electron-transfer pathway to the quenching reaction.Transient absorption spectra for the reaction between W6I14(2-)(excit.) and oxygen, however, do not display transients attributable to electron-transfer products.Accordingly, we ascribe the enhanced quenching rate of Y6(2-)(excit.) by oxygen to greater adiabaticity of the energy-transfer reactions of these ions as compared to their homologous cluster counterparts.The absence of an electron-transfer contribution to the Y6(2-)-cluster photosensitized production of 1O2 (Y6(2-)(excit.) + O2 -> Y6(1-) + O2(1-) -> Y6(2-) + 1O2) parallels the results observed for the photosensitized production of 1O2 by RuL3(2+) (L = plypyridyl) systems, which also produce singlet oxygen exclusively by energy transfer despite the existence of potential electron-transfer pathway.
- Jackson, Julie A.,Turro, Claudia,Newsham, Mark D.,Nocera, Daniel G.
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p. 4500 - 4507
(2007/10/02)
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- Studies Relating to the Oxidative Degradation of Natural Rubber. The Autoxidation of 1-Methylcyclohexene: Primary Product Analysis, Allylic Hydroperoxide Isolation, and Regiochemistry of the Initial Events
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The autoxidation of 1-methylcyclohexene has been examined; the regiochemistry of the initial events has been defined by direct examination and isolation of the first-formed products and a synthetically useful method has been developed in which t-butyl hydroperoxide-loaded mixtures undergo rapid, low temperature autoxidation.
- Courtneidge, John L.,Bush, Melanie
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p. 1227 - 1229
(2007/10/02)
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- Chemistry of Organolanthanoids. Lanthanoid-Mediated C-C Bond Formation and Cleavage and C-C Double Bond Reduction
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Reactions of the organolanthanoid ?-complexes RLnI with α,β-unsaturated carbonyl compounds and allylic alcohols under various conditions are described.An equivalent of RYbI reacts with α,β-unsaturated carbonyl compounds to give 1,2-addition products 1 regioselectively.On the other hand, the reaction of an excess of RYbI with chalcone gives C-C bond cleavage products 2 and 4 and deoxygenation product 3 instead of 1.In the reactions of PhYbI with benzalacetone or cinnamyl alcohol, compounds 5, derived from addition of RYbI to the C-C double bonds of the substrates, are obtained as main products.An excess of PhEuI reacts with α,β-unsaturated carbonyl compounds to give 2-4.C-C double bonds conjugated with phenyl group are hydrogenated by PhYbI/MeOH.Reduction of trans-stilbene with Yb/MeOD gives the deuteriated product 6a.
- Hou, Zhaomin,Fujiwara, Yuzo,Jintoku, Tetsuro,Mine, Norioki,Yokoo, Kazuhiro,Taniguchi, Hiroshi
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p. 3524 - 3528
(2007/10/02)
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- THE PREPARATION OF LITHIUM ORGANOCUPRATES FROM VARIOUS Cu(I) SALTS
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Various Cu(I) salts have been tested as precursors for organocuprates in side-by-side comparisons under controlled conditions.CuCN and CuBr*SMe2 appear to be superior to CuI, CuBr, and CuCl.CuSCN and CuOTf are also good precursors in some circumstances.
- Bertz, Steven H.,Gibson, Charles P.,Dabbagh, Gary
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p. 4251 - 4254
(2007/10/02)
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- ORGANOMANGANESE (II) REAGENTS XI. A Study of their Reactions with Cyclic Conjugated Enones : Conjugate Addition and Reductive Dimerization
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The reaction of organomanganese reagents such as RMnX, R2Mn, R3MnLi and R3MnMgX with cyclohexenone has been studied.Two major pathways have been observed : conjugate addition and β reductive dimerization.Similar results have been obtained with organomagnesium compounds in presence of a catalytic amount of manganous salts.
- Cahiez, G.,Alami, M.
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p. 569 - 572
(2007/10/02)
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- Photoassisted Oxygenation of Olefins: An Exchanged Zeolite as a Heterogenous Photosensitizer
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Ru(bpy)3(2+) exchanged into zeolite Y acts as an effective, heterogeneous singlet oxygen sensitizer.The photogenerated singlet oxygen freely diffuses to solution where it reacts with normal selectivity.The photocatalyst has high catalytic turnover, and it
- Pettit, Thomas L.,Fox, Marye Anne
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p. 1353 - 1354
(2007/10/02)
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- OXYDATION D'ALCENES CYCLIQUES PAR L'IODYLBENZENE CATALYSEE PAR L'ACETYLACETONATE DE VANADYLE
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Iodylbenzene with vanadyl acetylacetonate oxidizes cyclic alkenes, the experimental results accord with a free radical oxidation mechanism.
- Barret, R.,Pautet, F.,Daudon, M.,Mathian, B.
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p. 439 - 440
(2007/10/02)
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- DICYANOANTHRACENE SENSITIZED PHOTO-OXYGENATION OF OLEFINS. ELECTRON TRANSFER AND SINGLET OXYGEN MECHANISMS
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Cyanoaromatic sensitizers, in particular 9,10-dicyanoanthracene (DCA), sensitize the photooxygenation of olafins by two distinct mechanisms.In the case of aryl substituted olefins (OL), which react extremely slowly (if at all) with singlet oxygen, the reaction proceeds by way of electron transfer to produce discrete radical ions (DCA-. and OL+.).In the presence of oxygen, this ionic process results, ultimately, in the cleavage of the olefin to carbonyl compounds along with production of some epoxide and other minor byproducts.Aromatic ethers can interfere with this process by reducing the radical cation by electron transfer, resulting in net quenching of the reaction.With simple alkenes the DCA-sensitized reaction takes a different course, producing hydroperoxide products with distributions which are very similar to those obtained with the singlet oxygen ene reaction.Careful study has shown that this reaction does, indeed, proceed by way of singlet oxygen, which is produced by at least two mechanism: (1) enhanced intersystem crossing, in which 1DCA is quenched by interaction with the olefin, leading to a low yield of 3DCA, which subsequently reacts with oxygen to produce singlet oxygen; and (2) direct reaction of 1DCA with oxygen.At limiting high oxygen concentration, this process produces 2 mol of singlet oxygen for each mol of 1DCA quenched; the mechanism involves energy transfer to produce 3DCA and 1 mol of singlet oxygen; the 3DCA reacts again with oxygen to produce a second mol of singlet oxygen.The complex kinetic behaviour of simple olefins in the presence of DCA can be satisfactorily rationalized by these mechanisms.
- Foote, Christopher S.
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p. 2221 - 2228
(2007/10/02)
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- REACTIVITY OF CYCLOALKENES.
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The objective of this work is to investigate the kinetic relationships, to determine the composition of the products, and to elucidate the mechanism of their formation during liquid-phase oxidation of cyclohexene and of isomeric methylcyclohexenes (RH). Experiments show that the main products of oxidation of cyclohexene and of isomeric methylcyclohexenes are mixtures of hydroperoxides, unsaturated alcohols, ketones, and oxides. The isomeric methylcyclohexenes form the following series in order to selectivity of formation of methylcyclohexenols: 3-methylcyclohexene greater than 1-methylcyclohexene greater than 4-methylcyclohexene greater than cyclohexene; the corresponding series for alpha -oxide formation is 1-methylcyclohexene greater than 4-methylcyclohexene greater than 3-methylcyclohexene. A mathematical model of noncatalytic oxidation of cyclohexene has been formulated, and the rate constants of the process have been determined.
- Azhikova,Syroezhko,Proskuryakov
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p. 2133 - 2140
(2007/10/02)
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- ZWEI NEUE REAKTIONSWEISEN VON ALKYL-Mn(II)-VERBINDUNGEN: 1,4-ADDITION AN CYCLOHEX-2-ENON(1) UND DESOXYGENIERUNG VON OXIRANEN (1)
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Alkyl Mn(II) compounds react like alkyl Cu(I) compounds specifically or highly selectively with cyclohex-2-enone(1) to give 3-alkylhexanones (Alk = Me, Bu) in medium or good yields.By reacting with oxiranes corresponding alkenes are produced, a reaction not observed so far with alkyl Cu(I) reagents.
- Kauffmann, Thomas,Bisling, Monika
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p. 293 - 296
(2007/10/02)
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- CHEMISTRY OF SINGLET OXYGEN. 47. 9,10-DICYANOANTHRACENE-SENSITIZED PHOTOOXYGENATION OF ALKYL-SUBSTITUTED OLEFINS.
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9,10-Dicyanoanthracene (DCA) sensitizes the photooxygenation of 1-methylcyclohexene, 1,2-dimethylcyclohexene, and cholesterol in acetonitrile and benzene. For all three olefins, the products are the same as those formed by reaction with singlet oxygen. Th
- Araki,Dobrowolski,Goyne,Hanson,Zhi Qui Jiang,Lee,Foote
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p. 4570 - 4575
(2007/10/02)
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