- SELECTIVE HYDROFORMYLATION OF CYCLODIENES TO CYCLOALKENECARBOXALDEHYDES USING CATALYSTS DERIVED DIRECTLY FROM Rh VAPOUR AND CYCLODIENES
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Cocondensation of Rh atoms with cyclodienes at liquid nitrogen temperature yields Rh complexes, thermally stable in excess of the ligand, which are good catalysts for the selective hydroformylation of cyclodienes to cycloalkenecarboxaldehydes.
- Salvadori, Piero,Vitulli, Giovanni,Raffaelli, Andrea,Lazzaroni, Raffaello
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- Highly Efficient Regeneration of Carbonyl Compounds from Oximes, Tosylhydrazones, 1,3-Dithiolanes, and 1,3-Dithianes Using Cupric Nitrate Supported on Silica Gel
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Cupric nitrate supported on silica gel is exceptionally efficient in regenerating aldehydes and ketones from oximes, tosylhydrazones, 1,3-dithiolanes, and 1,3-dithianes.
- Lee, Jong Gun,Hwang, Je Pil
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- Visible-Light-Driven Photocatalytic Oxidation of Organic Chlorides Using Air and an Inorganic-Ligand Supported Nickel-Catalyst Without Photosensitizers
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Engineering photoredox-triggered chemical transformation via visible light has been an emerging area in organic synthesis. However, most of the well-established photocatalysts are based upon either transition metal complexes involved with noble metals and organic ligands or photosensitive organic dyes, the development of pure inorganic molecular photocatalysts that could provide better stability and durability is greatly retarded. Herein we discover that the Anderson polyoxometalate (POM) Na4[NiMo6O18(OH)6] (1), which consists of pure inorganic framework built from a central NiII core supported by six MoVIO6 inorganic scaffold/ligands, can be used as a powerful photocatalyst. Upon irradiation with visible light (>400 nm), the compound can catalyze, in high efficiency, a wide range of reactions, including the oxidative cross-coupling reaction of chlorides with amines, as well as oxidation of chlorides using molecular oxygen, affording various imines, aldehydes, and ketones, respectively in high selectivity and good yields. Owing to the robust inorganic framework, this catalyst exhibits excellent stability during the catalysis and reusability with little loss of the catalytic activity, thus providing an alternative without use of complicated organic ligands and expensive noble metal-based photosensitizers.
- Yu, Han,Wang, Jingjing,Zhai, Yongyan,Zhang, Mengqi,Ru, Shi,Han, Sheng,Wei, Yongge
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- Studies on Transition-Metal Oxo and Nitrido Complexes. Part 10. New Oxo-Ruthenium and Oxo-Osmium Pyridine Complexes, and Use of the Former as Catalysts for Oxidation of Alcohols
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The new complexes trans-(2+), trans-(2+), trans- (M=Ru or Os; X=Cl or Br; py= pyridine) and trans- are reported.Both tans-(2+) and trans- in CH2Cl2 are efficient oxidants for primary alcohols to aldehydes and secondary alcohols to ketones, and function catalytically, with N-methylmorpholine N-oxide (mmo) or n4> as co-oxidants.A simple preparation of trans- and the isolation of , , and OsO2L2(O2C6H10)> (L=pyridine N-oxide) are also reported. Complexes were characterised by Raman, i.r. and (1)H n.m.r.spectroscopy.
- El-Hendawy, Ahmed M.,Griffith, William P.,Taha, Fatma I.,Moussa, Mahmoud N.
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- Rhodium-Catalyzed C,C-Double Bond Cleavage by Molecular Oxygen
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Acetylacetonatorhodiumolefin systems, allylrhodium complexes, or (Ph3P)3RhCl catalyzed the conversion of alkenes and molecular oxygen to carbonyl compounds via C=C-bond cleavage.For example, 2,3-dimethyl-2-butene was transformed into acetone.Butadiene and isoprene also undergo oxidative C=C-bond cleavage to form acrylaldehyde and related compounds.
- Boennemann, Helmut,Nunez, Washington,Rohe, Dieter M. M.
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- Homogeneous green catalysts for olefin oxidation by mono oxovanadium(V) complexes of hydrazone Schiff base ligands
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Three mono oxovanadium(V) complexes of tridentate Schiff base ligands [VO(OMe)L'] (1), [VO(OMe)L2] (2) and [VO(OMe)L3] (3) obtained by monocondensation of 3-hydroxy-2-naphthohydrazide and aromatic o-hydroxyaldehydes have been synthesized (H2L2 - (E)-3-hydroxy-N′-(2-hydroxy-3-methoxybenzylidene)-2-naphthohydrazide, H2L2 - (E)-3-hydroxy-N′-(2-hydroxybenzylidene)-2- naphthohydrazide and H2L3 - (E)-N′-(5-bromo-2- hydroxybenzylidene)-3-hydroxy-2-naphthohydrazide). The complexes were characterized by spectroscopic methods in the solid state (IR) and in solution (UV-Vis, 1H NMR). Single crystal X-ray analyses were performed with 1 and 2. The catalytic potential of these complexes has been tested for the oxidation of cyclooctene using H2O2 as the terminal oxidant. The effects of various parameters including the molar ratio of oxidant to substrate, the temperature, and the solvent have been studied. The catalyst 2 showed the most powerful catalytic activity in oxidation of various terminal, cyclic and phenyl substituted olefins. Excellent conversions have been obtained for the oxidation of cyclic and bicyclic olefins.
- Monfared, Hassan Hosseini,Bikas, Rahman,Mayer, Peter
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- Alkene Epoxidations Catalyzed by Iron(III), Manganese(III), and Chromium(III) Porphyrins. Effects of Metal and Porphyrin Substituents on Selectivity and Regiochemistry of Epoxidation
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The products of epoxidation of norbornene, cyclohexene, and adamantylideneadamantane with pentafluoroiodobenzene using as catalysts variously substituted tetraphenylporphyrin complexes of chloroiron(III), chloromanganese(III), and chlorochromium(III) have been determined.All catalysts afforded the epoxide from adamantylideneadamantane, suggesting that the metallacycle intermediate, impossible in this case, is not required for epoxidation.The ratios of exo- to endo-epoxynorbornanes obtained from norbornene varied from about 1E3 for electropositively substituted Cr(III) complexes gradually through the Mn(III) and Fe(III) series to a value of about 6 for electronegatively substituted iron(III) porphyrins.Mechanisms ranging from limiting electrophilic addition to limiting electron transfer are proposed to account for these changes.The electronegatively substituted iron porphyrins show a greater tendency toward epoxidation rather than allylic oxidation and show more selectivity for cis-alkenes.
- Traylor, Teddy G.,Miksztal, Andrew R.
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- Olefin Oxidation Catalyzed by Electron Deficient Metallo-Porphyrin
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Olefin oxidations catalyzed by Fe or Mn complexes of 2,4,6,8-tetratrifluoromethyl-1,3,5,7-tetraethylporphyrin (TFTEP) using iodosobenzene as oxidant were investigated.Comparison of TFTEP with usual OEP/iodosobenzene systems shows that the electronic effec
- Ogoshi, Hisanobu,Suzuki, Yasuhiko,Kuroda, Yasuhisa
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- Reduction of Organic Compounds with Rare-Earth Intermetallics Containing Absorbed Hydrogen
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The hydrogenation of organic compounds with rare-earth intermetallic hydrides has been investigated.Alkynes,alkenes,aldehydes,ketones,nitriles,imines, and nitro compounds are hydrogenated in excellent yields with LaNi5H6 or LaNi4.5Al0.5H5 at 0-60 deg C.The present hydrogenation method has the following characteristic features. (1) The intermetallic compounds (alloys) are not poisoned by compounds containing an amino group or a halogen atom. (2) The alloys can be used repeatedly without decrease in activity. (3) The reaction conditions are mild, and selective hydrogenations of some organic functional groups can be achieved.The reaction mechanism of this hydrogenation is briefly discussed in terms of stereochemistry and H/D exchange reactions.
- Imamoto, Tsuneo,Mita, Takeshi,Yokoyama, Masataka
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- Rhodium complex catalyzed hydroformylation reactions of linear and cyclic mono- and diolefins
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The hydroformylation reactions of cyclopentene, cyclohexene, 4-vinylcyclohexene, cycloheptene and cyclooctene, catalyzed with a Rh(acac)2/P(OPh)3 (I) system at 80 deg C and 10 atm (CO+H2), have been studied.Only cyclopentene and 4-vinylcyclohexene undergo hydroformylation at 1 atm and 40 deg C.The hydroformylation of some cyclic dienes; (1,3- and 1,4-cyclohexadienes, 1,3- and 1,5-cyclooctadienes and 1,3-cyclopentadiene), at 10 atm and 80 deg C, was investigated in two catalytic systems: (I) and Rh(acac) (CO) (PPh3) / PPh3 (II).The main reaction products of cyclohexadienes and pentadiene (at 80 deg C, 10 atm) are unsaturated monoaldehydes.In hydroformylation of 1,5-cyclooctadiene the main product is formylcyclooctane.Key words: Rhodium; Olefins; Hydroformylation
- Trzeciak, Anna M.,Ziolkowski, Jozef J.
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- The competitive and non-competitive hydroformylation of conjugated dienes starting with tetrarhodium dodecacarbonyl. An in-situ high-pressure infrared spectroscopic study
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It is well known that the liquid-phase homogeneous unmodified rhodium catalysed hydroformylation of alkenes is poisoned by the presence of trace quantities of conjugated dienes. Nevertheless, some hydroformylation of conjugated dienes is possible with unmodified rhodium, and this reaction is in general slower than alkene hydroformylations at comparable reaction conditions. In the present contribution, we examined (A) the catalytic behaviour of alkenes in the presence of trace conjugated diene impurities and (B) the catalytic behaviour of a variety of dienes using Rh4(CO)12 in n-hexane solvent at 293 K under 1.0-4.0 MPa CO and 0.5-2.0 MPa H2. The analytic method was in-situ high-pressure infrared spectroscopy. It was observed that (I) in the hydroformylation of poisoned alkenes, most of the rhodium reacts with the trace quantity of conjugated dienes and not the alkenes in this competitive situation and (II) the metal carbonyl spectra of the hydroformylation of a variety of dienes are very similar. The primary absorbance maxima observed in the hydroformylations of conjugated dienes occur at circa 2109, 2091, 2087, 2064, 2049, 2037, 2030, 2020, 2012, 1999, and 1990 cm-1. Given the known chemistry Of Rh4(CO)12 under syngas, and the very well documented chemistry of Rh4(CO)12 under alkene hydroformylation conditions, the lack of bridging carbonyls in the present experiments strongly suggested that the new infrared vibrations are due to mononuclear rhodium species. Preliminary analysis suggests the presence of at least three new species. In particular, the formation of observable η3 allyl rhodium tricarbonyl species, σ allyl rhodium tetracarbonyl species and even acyl rhodium tetracarbonyl species RCORh(CO)4 (R = alkenyl and/or formylalkyl) seems probable. Characteristic wavenumbers of 2108, 2064, 2037, 2020 and 1700 cm-1 are tentatively assigned to the latter. The reduced hydroformylation activity in the competitive hydroformylation of alkenes arises due to the much higher affinity of rhodium complexes for conjugated dienes than for alkenes under otherwise similar reaction conditions.
- Liu, Guowei,Garland, Marc
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- The Cycloaddition of the 1,3-Butadiene Radical Cation with Acrolein and Methyl Vinyl Ketone
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The 1,3-butadiene radical cation reacts with acrolein and methyl vinyl ketone to produce 'stable' adducts.The nature of the reaction and the structures of the adducts were investigated by collisional activation decomposition (CAD) combined with tandem mas
- Castle, Lyle W.,Gross, M. L.
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- Photochemical oxygenation of olefins by heterocyclic n-oxides: mechanistic characteristics in the photochemistry of pyrimidopteridine-10-oxide
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A novel heterocyclic N-oxide, pyrimidopteridine-10-oxide (1), oxygenates cyclohexene (4) and norbornene (9) under the photochemical conditions to give the corresponding oxidation products, (5) - (8) and (10) - (12), respectively.Experimental results clearly indicate that the photochemical oxygenation by (1) involves a single-electron transfer from the olefins (4) and (9) to the singlet-excited (1) followed by oxygen-atom transfer rather than oxene mechanism.
- Maki, Yoshifumi,Sako, Magoichi,Murase, Toshinobu,Kitade, Yukio,Hirota, Kosaku
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- Visible-Light-Induced Efficient Selective Oxidation of Nonactivated Alcohols over {001}-Faceted TiO2 with Molecular Oxygen
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In the presence of molecular oxygen, a {001}-faceted nanocrystalline anatase TiO2 catalyst enabled the selective oxidation of nonactivated aliphatic alcohols to the corresponding aldehydes or ketones under visible light. The reaction shows excellent conversion and selectivity towards the formation of the carbonyl products without over-oxidation to the corresponding carboxylic acids. The exceptional reactivity of the catalyst is possibly due to the absorption of visible light originating from a stronger interaction of alcohol with the {001} facet, which facilitates the modification of the band structure of TiO2, thus facilitating the photogenerated hole transfer and subsequent oxidation processes. The experimental results have also been corroborated by first-principles quantum chemical DFT calculations.
- Vadakkekara, Raji,Biswas, Abul Kalam,Sahoo, Tapan,Pal, Provas,Ganguly, Bishwajit,Ghosh, Subhash Chandra,Panda, Asit Baran
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- A high-performance selective oxidation system for the facile production of fine chemicals
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MnIIIAlPO-5 and CrVIAlPO-5 redox (microporous) catalysts are effective, in the presence of dissolved acetylperoxyborate (APB) under mild conditions (333-373 K), and much superior to the titanosilicate, TS-1 (also a single-site heterogeneous catalyst), in the selective oxidation of primary, secondary, benzylic and other unsaturated alcohols, p-cymene, methyl cyclohexene and other speciality organics which are of value in the fine-chemical and pharmaceutical industries. The Royal Society of Chemistry.
- Raja, Robert,Thomas, John Meurig,Greenhill-Hooper, Mike,Doukova, Violeta
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- Efficient epoxide isomerization within a self-assembled hexameric organic capsule
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The isomerization of epoxides to the corresponding carbonyl compounds is efficiently catalyzed by the supramolecular organic nano-capsule formed by the self-assembly of six resorcin[4]arene units. The capsule provides a combination of weak Br?nsted acidity and a suitable nano-environment that favors the metal-free isomerization reaction.
- Caneva, Thomas,Sperni, Laura,Strukul, Giorgio,Scarso, Alessandro
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- Cyclohexyldimethanol synthetic method, catalyst and use thereof (by machine translation)
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The present invention provides a method for synthesis of cyclohexane dimethanol, comprises the following steps: under the action of catalyst, cyclohexene formaldehyde by the hydroformylation reaction and hydrogenation reaction to make said cyclohexyldimet
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Paragraph 0059-0061; 0065-0067
(2018/05/16)
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- METHOD FOR OXIDIZING ALCOHOLS
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A method for oxidizing an alcohol, wherein oxidation is performed in the presence of a compound represented by the following formula (I) and a bulk oxidant, which enables efficient oxidation of secondary alcohols as well as primary alcohols, and can attain high reaction efficiency even when air is used as a bulk oxidant.
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Paragraph 0133; 0134
(2013/06/05)
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- Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system
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The combination of 1,4-benzoquinone and a catalytic amount of NaI was found to be effective for the deprotection of dithioacetals. The reactions proceeded efficiently under mild, near-neutral reaction conditions, producing a wide range of aryl and alkyl aldehydes and ketones generally in high yields with good functional group compatibility. The method developed therefore represents a general, facile, and highly applicable approach for deprotecting dithioacetals.
- Inamoto, Kiyofumi,Yamada, Tetsuya,Kato, Sei-Ichi,Kikkawa, Shoko,Kondo, Yoshinori
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p. 9192 - 9199
(2013/10/01)
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- REGENERATION OF A HYDROFORMYLATION CATALYST DURING HYDROFORMYLATION
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A method for hydroformylating or hydrocarbonylating a substrate having a carbon-carbon double or triple bond or both is described. The method comprises exposing the substrate to a hydroformylation catalyst under an atmosphere comprising carbon monoxide and hydrogen in the presence of a regeneration reagent so as to form a product. The regeneration reagent is such that it is capable of at least partially reversing poisoning of the hydroformylation catalyst by a diene or an alkyne or both.
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(2011/04/14)
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- Designing the synthesis of catalytically active Ti-β by using various new templates in the presence of fluoride anion
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Crystallization of large-pore Ti-β by using a variety of diquaternary ammonium derivatives of dibromoalkane and amines such as triethylamine, 1,4-diazabicyclo[2,2,2]octane (DABCO), and quinuclidine as structure-directing agents (SDA) is described. The size of hydrophobic bridging alkyl-chain length of the template [R3N+-(CH2)x-N +R3](OH-)2 directs the final crystalline product: Ti-β, Ti-ZSM-12, Ti-nonasil or Ti-ZSM-5, as x gradually changes from 6 to 1, in the fluoride medium under hydrothermal conditions. A dense phase such as Ti-nonasil (clathrasil type) is crystallized as the size of hydrophobic bridging alkyl-chain length decreases. The use of F- anions as a mineralizer and Ti4+ as a heteroatom in the synthesis gel also influences the selectivity of final crystalline product. The phase purity and incorporation of Ti4+ into the lattice of β (BEA) and ZSM-12 frameworks are confirmed using XRD, UV-visible, FT-IR, 29Si NMR spectroscopes, elemental analysis (ICP), surface area measurements and catalytic test reactions. The morphology of Ti-β samples is dependent on the nature of the structure-directing agent as revealed by the scanning electron microscopic (SEM) observations. The catalytic activity in the epoxidation of 4-vinyl-1-cyclohexene is increased with the amount of tetrahedral Ti4+ atoms in the framework. The new templates can be effectively used for preparation of catalytically active Ti-β with the minimum number of framework defect sites.
- Sasidharan, Manickam,Bhaumik, Asim
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experimental part
p. 16282 - 16294
(2012/01/14)
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- Erbium triflate in ionic liquids: A recyclable system of improving selectivity in Diels-Alder reactions
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The efficiency of Er(OTf)3 in promoting the Diels-Alder reactions between different dienes and dienophiles in ionic liquids has been investigated. Compared with the analogous cycloadditions performed in conventional solvents shorter reaction times are required to obtain good/excellent yields. In most cases an enhancement of regio- and endo:exo selectivity was observed. The role of the ionic liquid, as a function of the cationic part, i.e. the imidazolium based or the pyridinium based, is discussed well. The ILs containing the catalyst can be readily separated from the reaction products and recovered in very high purity for direct reuse, up to six cycles.
- Bortolini, Olga,De Nino, Antonio,Garofalo, Angelo,Maiuolo, Loredana,Procopio, Antonio,Russo, Beatrice
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experimental part
p. 124 - 129
(2011/02/16)
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- Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2] 2+ (dmp = 2,9-dimethylphenanthroline)
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(Chemical Equation Presented) [cis-Ru(II)(dmp)2(H 2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral.
- Kogan, Vladimir,Quintal, Miriam M.,Neumann, Ronny
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p. 5039 - 5042
(2007/10/03)
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- Trifluoromethylthiocopper catalyzed oxirane ring opening
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Trifluoromethylthiocopper has been found to catalyze the opening of the epoxide ring and to furnish not-so-easily accessible novel trifluoromethylthiolated α-hydroxy compounds. This communication presents the mechanism of the formation of the various comp
- Munavalli,Rohrbaugh,Durst
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p. 1657 - 1671
(2007/10/03)
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- Catalytic osmium-assisted oxidative cleavage of olefins
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An osmium-assisted process for the oxidative cleavage of oxidizable organic compounds such as unsaturated organic compounds, including alkenes and olefins into aldehydes, carboxylic acids, esters, or ketones. The process uses a metal catalyst comprising osmium and a peroxy compound selected from the group consisting of peroxymonosulfuric acid and salts thereof to oxidatively cleave the oxidizable organic compound. In particular, the process enables aldehydes, carboxylic acids, esters, or ketones to be selectively produced from the corresponding mono-, 1,1-di-, 1,2-di-, tri-, or tetra-substituted olefins in a reaction that produces the result of ozonolysis but with fewer problems. The present invention further provides a process for oxidizing an aldehyde alone or with the osmium in an interactive solvent to produce an ester or carboxylic acid.
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- A Mild and Efficient Oxidation of Alcohols to Carbonyl Compounds by Periodic Acid Catalyzed by 2,2,6,6-Tetramethylpiperidinyl-1-oxyl
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Numerous alcohols are effectively oxidized to corresponding aldehydes and ketones with H5IO6-TEMPO. The rate of oxidation parallels decreasing α-C-H bond dissociation energy, that is secondary alcohols react faster than primary alcohols.
- Kim, Sung Soo,Nehru, Kasi
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p. 616 - 618
(2007/10/03)
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- Iodomethane oxidation by dimethyldioxirane: A new route to hypoiodous acid and iodohydrines
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matrix presented The oxidation of iodomethane with dimethyldioxirane allows the generation of stable neutral solutions of hypoiodous acid in the absence of any trapping agent for iodide anion. Hypoiodous acid is trapped in situ by addition to representative olefins to give iodohydrines in good yields. The stereochemical study of the products shows the anti-stereospecific nature of the iodohydroxylation reaction.
- Asensio, Gregorio,Andreu, Cecilia,Boix-Bernardini, Carmen,Mello, Rossella,Gonzalez-Nunez, Maria Elena
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p. 2125 - 2128
(2008/02/09)
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- Ligand nature control epoxidation stereochemistry
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The epoxidation of norbornene using Mn(T4PyP)OAc give exo and endo-norbornene oxide while epoxidation with Mn(T3PyP)OAc give only exo-norbornene oxide in high yield.Sodium lauryl sulphate addition increase the yield of endo-norbornene oxide 2.5 fold while triton-X-100 addition decrease the epoxide yield.CTABr decrease endo-epoxide formation 27 fold suggesting a carbocation intermediate.The results suggest that in Mn(T3PyP)OAc coordination through pyridyl nitrogen pull the manganese in the porphyrin plane and put a steric barrier to rotation.
- Agarwal, D. D.,Jain, R.,Rastogi, R.,Agarwal, V.
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p. 303 - 304
(2007/10/02)
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- Epoxidation of alkenes using MnIII(SAP)-NCS as catalyst
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Epoxidation of cyclohexene gives mainly the cyclohexene oxide as the product.It is promoted when pyridine and imidazole are used for axial ligation .Increase in the catalyst results in the formation of μ-oxo dimer.The relative rates of cycloole ns follow
- Agarval, D D,Rastogi, R,Sharma, Lakshi
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p. 128 - 130
(2007/10/02)
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- EFFICIENT CYCLOADDITION DURING ADSORPTION ON CHROMATOGRAPHIC SOLVENTS
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An essentially new method was developed for carrying out cycloaddition on the surface of chromatographic adsorbents in the absence of solvent.This method permits the use of much milder reaction conditions and to increase the reaction's selectivity.
- Veselovskii, V. V.,Gybin, A. S.,Lozanova, A. V.,Moiseenkov, A. M.,Smit, V. A.
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- Catalysis of Diels-Alder Reactions with Acrolein as Dienophile by Iron(III)-Doped Montmorillonite
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Acrolein is improved as a dienophile in the presence of the K10 montmorillonite exchanged with iron(III).Cycloaddition occurs with a number of dienes at room temperature and in high yield.Dienes tested include butadiene, isoprene, cyclopentadiene, cyclohexadiene, 1-methoxycyclohexadiene, anthracene.
- Laszlo, Pierre,Moison, Helene
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p. 1031 - 1034
(2007/10/02)
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- Protolytic Cleavage of Tricyclo2,7>hept-3-ene
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Acidolyses of the title compound 9 were performed in aqueous dioxane and in acetic acid to give eight alcohols (5-8, 10-13) among which bicyclohept-2-en-exo-6-ol (13) was novel.Comparison with independent routes to the various cationic intermediates reveals that the double bond and the cyclopropane ring of 9 react at similar rates and with high regioselectivity.Protonation occurs preferentially, if not exclusively, at C-4 and C-7.
- Kirmse, Wolfgang,Streu, Joachim
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p. 551 - 554
(2007/10/02)
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- DRAMATIC ACCELERATION OF THE DIELS-ALDER REACTION BY ADSORPTION ON CHROMATOGRAPHY ADSORBENTS
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The development of a new method for effecting cycloadditions on the surface of chromatographic adsorbents in the absence of solvents that leads to a moderation of the reaction conditions and an increase in selectivity is described.
- Veselovsky, V. V.,Gybin, A. S.,Lozanova, A. V.,Moiseenkov, A. M.,Smit, W. A.,Caple, R.
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p. 175 - 178
(2007/10/02)
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- CATALYSIS OF HOMO DIELS-ALDER REACTIONS BY YB(FOD)3
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The use of Yb(fod)3 to catalyze Diels-Alder reactions of acrolein with sensitive dienes in nearly stoichiometric ratio and with high stereoselectivity is described.
- Danishefsky, Samuel,Bednarski, Mark
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p. 2507 - 2508
(2007/10/02)
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- ALIPHATIC CLAISEN REARRANGEMENT PROMOTED BY ORGANOALUMINIUM REAGENTS.
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Organoaluminium compounds, R//3Al, promote the Claisen rearrangement of allyl vinyl ether derivatives at room temperature under transfer of R or H as a nucleophile to the aldehydic carbon. Treatment of 1-butyl-2-propenyl vinyl ether with a hexane solution of Me//3Al (1. 0 M, 2. 2 equiv) in CH//2ClCH//2Cl at 25 degree C afforded 5-decen-2-ol (91% yield, E/Z equals 47/53), which was produced by the left bracket 3,3 right bracket sigmatropic rearrangement and successive methylation. The rearrangements with alkynylation, alkenylation, and hydrogenation are also achieved. The regular Claisen rearrangement products, of gamma , delta -unsaturated aldehydes (ketones), are obtained at 25 degree C in good to excellent yields with Et//2AlSPh (2. 5 equiv) or the combination of Et//2AlCl (2. 0 euiv) and PPh//3 (2. 2 equiv).
- Takai,Mori,Oshima,Nozaki
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p. 446 - 451
(2007/10/02)
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- ALIPHATIC CLAISEN REARRANGEMENT PROMOTED BY ORGANOALUMINIUM COMPOUNDS
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Treatment of allyl vinyl ether derivatives with organoaluminium amphoteric reagent, R3Al or R2AlSPh, results in the title reaction at room temperature under uptake of R, H, or SPh as a nucleophile on the aldehydic carbon.
- Takai, Kazuhiko,Mori, Ichiro,Oshima, Koichiro,Nozaki, Hitosi
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p. 3985 - 3988
(2007/10/02)
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- CHEMISTRY OF ENOL ETHERS. LIII. PROTOTROPIC ISOMERIZATION IN THE SERIES OF CYCLIC 1-ALKOXY-1,4-DIENES
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A series of diethyl acetals of 1-cyclohexene-3-carbaldehydes, the pyrolysis of which leads to the formation of cyclic 1-ethoxy-1,4-dienes, were obtained by the acetalization of 1-cyclohexene-3-carbaldehydes, which were obtained by the condensation of conjugated dienes with α,β-unsaturated aldehydes.The prototropic isomerization of the 1-ethoxy-1,4-dienes to corresponding 1-ethoxy-1,3-dienes under the influence of potassium tert-butoxide in dimethyl sulfoxide solution was investigated.
- Makin, S. M.,Pomogaev, A. I.,Boiko, T. N.,Nikiforova, A. P.
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p. 2033 - 2036
(2007/10/02)
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