- Oxidation by Cobalt(III) Acetate. Part 4. Kinetics and Mechanism of the Oxidation of Glycols in Acetic Acid
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The oxidative cleavage of 1,2-glycols by cobalt(III) acetate in acetic acid was studied kinetically in order to clarify the reaction mechanism.The rates were first-order in both cobalt(III) acetate and substrate for the oxidation of all the diols used. cis-Cyclopentane-1,2-diol and decalin-9,10-diol were more rapidly oxidized than the corresponding trans-isomers, respectively, whereas cis-cyclohexane-1,2-diol was more slowly oxidized than the trans-isomer.The oxidation of trans-2-methoxycyclohexanol was much slower than that of the corresponding diol.The mechanism involving the formation of a bidentate complex between cobalt(III) acetate dimer and glycol is discussed.
- Morimoto, Takashi,Hirano, Masao
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- Solvent Effect in the Thermal Decomposition Reaction of trans-3,3-Dimethyl-5,6-tetramethylene-1,2,4-trioxacyclohexane
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The kinetic data of the thermal decomposition reaction of trans-3,3-dimethyl-5,6-tetramethylene-1,2,4-trioxacyclohexane has been measured in different solvents (benzene, toluene, 2-propanol, 2-methoxyethanol, and p-dioxane) at 0.02 mol kg-1 initial concentration and in the temperature range of 135.0-165.0°C. The enthalpy and entropy of activation of the unimolecular reaction of this trioxane in several organic solvents have been correlated through "isokinetic relationships" to validate the existence of a genuine solvent effect on that reaction.
- Eyler, Gladys N.,Canizo, Adriana I.,Mateo, Carmen M.,Alvarez, Elida E.,Cafferata, Lazaro F. R.
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- Catalytic aerobic oxidation of diols under photo-irradiation: Highly efficient synthesis of lactols
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Aerobic oxidation of 1, n- and 1,ω-diols with (ON)Ru(salen) 1 as the catalyst was found to give the corresponding lactols in almost quantitative yields. Furthermore, in the oxidation of 2,2-dimethylalkane-1,ω-diols, less sterically hindered ω-alcohols were found to be preferentially oxidized when (ON)Ru(salen) 6 was used as the catalyst. n-Decanol was preferentially oxidized in the presence of 2,2-dimethylpropanol also by using 6 as the catalyst.
- Miyata, Atsushi,Furukawa, Mizuki,Irie, Ryo,Katsuki, Tsutomu
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- Oxidation of Cyclohexene in the Presence of Transition-Metal-Substituted Phosphotungstates and Hydrogen Peroxide: Catalysis and Reaction Pathways
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Homogeneous catalytic oxidations of cyclohexene by transition-metal-substituted phosphotungstates [PW11M(L)O39]m? (PW11M, M=CoII, CuII, FeIII, NiII, MnII, L=H2O or absence) with hydrogen peroxide in acetonitrile were experimentally studied. The catalytic activities of allylic oxidation were found to strongly depend on the transition metals, and PW11Co showed the highest activity. The product distribution and the catalyst stability were dominated by mole ratio of hydrogen peroxide to PW11M, whereby low or high mole ratios led to stable structure of PW11M and predominant formation of allylic oxidation products or decomposition of PW11M, respectively. Different from the activation of the allylic C?H bond by radicals, the oxidation of C=C double bond was based on tungsten-peroxo species. A reaction mechanism composed of radical and nonradical processes was proposed from NMR, EPR, and kinetic data, to describe the reaction pathways of cyclohexene oxidation.
- Song, Yuexiao,Xin, Feng,Zhang, Lexiang,Wang, Yong
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- Asymmetric syntheses of the N-terminal α-hydroxy-β-amino acid components of microginins 612, 646 and 680
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The asymmetric syntheses of the N-terminal α-hydroxy-β-amino acid components of microginins 612, 646 and 680 are reported. Conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to the requisite (E)-α,β-unsaturated ester followed by in situ enolate oxidation with (?)-(camphorsulfonyl)oxaziridne (CSO) gave the corresponding anti-α-hydroxy-β-amino esters. Sequential Swern oxidation followed by diastereoselective reduction gave the corresponding syn-α-hydroxy-β-amino esters. Subsequent N-debenzylation (i.e., hydrogenolysis for microginin 612, and NaBrO3-mediated oxidative N-debenzylation for microginins 646 and 680) followed by acid catalysed ester hydrolysis gave the corresponding syn-α-hydroxy-β-amino acids, the N-terminal components of microginins 612, 646 and 680, in good yield. An analogous strategy for elaboration of the enantiopure anti-α-hydroxy-β-amino esters facilitated the asymmetric synthesis of the corresponding C(2)-epimeric α-hydroxy-β-amino acids.
- Davies, Stephen G.,Fletcher, Ai M.,Hanby, Abigail R.,Roberts, Paul M.,Thomson, James E.
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- Products of the gas-phase reaction of O3 with cyclohexene
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In the troposphere, alkenes react with OH radicals, NO3 radicals, and O3, with the O3 reactions often being an important transformation process during both daytime and nighttime. The reactions of O3 with alkenes lead to the production of OH radicals, often in high yield, and these reactions also lead to the formation of secondary organic aerosol. Products of the gas-phase reactions of O3 with cyclohexane and cyclohexene-d10 were studied in the presence of OH radical scavengers by gas. Cyclohexane and cyclohexene-d12 were used as OH radicals. In the cyclohexene reaction in the presence of sufficient cyclohexane to scavenge >95% of the OH radicals formed, 1.47 × 1014 molecule/cu cm of O3 consumed 1.62 × 1014 molecule/cu cm of cyclohexene, with a 3.5% yield of HC(O)OH which increased to 4.5% after 17 min. Addition of butanal to the reactant mixtures resulted in changes in the post-reaction API-MS spectra. Adipaldehyde could be formed from reaction of the thermalized Criegee intermediate (presumably the anti-intermediate) with water vapor. OH (or OD) radical formation yields were also measured from the reactions of O3 with propylene (40 ± 6%).
- Aschmann, Sara M.,Tuazon, Ernesto C.,Arey, Janet,Atkinson, Roger
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- Formation of Dicarbonyl Compounds in the Flash Vacuum Pyrolysis of Saturated Bicyclic Peroxides
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Under flash vacuum pyrolysis, dioxabicycloalkanes (n = 3,4, and 5) isomerise to keto-aldehydes, MeCOnCHO, whereas dioxabicycloalkanes (n = 2,3, and 4) fragment to give, by loss of hydrogen and ethylene, mixtures of cycloalkane-1,4-diones and dialdehydes, OHCnCHO.
- Bloodworth, A. J.,Baker, David S.,Eggelte, Henny J.
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- Catalytic properties of the polyoxometalate [Ti2(OH) 2As2W19O67(H2O)] 8- in selective oxidations with hydrogen peroxide
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The catalytic properties of the sandwich polyoxometalate [Ti 2(OH)2As2W19O67(H 2O)]8-, which contains two (B-α-As IIIW9O33) fragments linked together by a "belt" consisting of one octahedral WO(H2O)4+ and two square-pyramidal Ti(OH)3+ groups, have been investigated in the selective liquid-phase oxidation of organic compounds by aqueous hydrogen peroxide. The polyoxometalate shows high catalytic activity and selectivity in the oxidation of alkenes, alcohols, diols, and thioethers. The composition of the reaction products indicates that hydrogen peroxide is activated via a heterolytic mechanism. Pleiades Publishing, Ltd., 2010.
- Donoeva,Trubitsyna,Al-Kadamany,Kortz,Kholdeeva
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- A novel and efficient asymmetric synthesis of carbon-14 labeled (S, S)-2,7-di-boc-diamino[1,8-14C2]suberic acid
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Five hundred mCi of Potassium [14C]cyanide at a specific activity of 51 mCi/mmol was used to diastereoselectively introduce the carbon-14 label into 1,6-hexanedial via a thermodynamically controlled asymmetric Strecker reaction using (R)-(-)-2-phenylglycinol as the chiral auxiliary. The expected and predominant (R, S/S, R) diastereomer (2) was separated by preparative normal phase HPLC. The chiral auxiliary was removed by oxidation with lead tetraacetate and the resulting benzylimino nitrile exhaustively hydrolyzed in hydrochloric acid to give (S,S)-2,7-diamino[1,8-14C2]suberic acid (6). Subsequent acylation with di-tert-butyldicarbonate gave the title compound (1) with a radiochemical purity of 95,5%, a specific activity of 113 mCi/mmol, and an enantiomeric purity of 95.5% e.e. To our knowledge this is the first report of the asymmetric Strecker methodology being applied to the synthesis of a carbon-14 labeled amino acid. Copyright
- Villani,Saunders,Shu,Heys
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- Production of Hydroxy Acids: Selective Double Oxidation of Diols by Flavoprotein Alcohol Oxidase
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Flavoprotein oxidases can catalyze oxidations of alcohols and amines by merely using molecular oxygen as the oxidant, making this class of enzymes appealing for biocatalysis. The FAD-containing (FAD=flavin adenine dinucleotide) alcohol oxidase from P. chrysosporium facilitated double and triple oxidations for a range of aliphatic diols. Interestingly, depending on the diol substrate, these reactions result in formation of either lactones or hydroxy acids. For example, diethylene glycol could be selectively and fully converted into 2-(2-hydroxyethoxy)acetic acid. Such a facile cofactor-independent biocatalytic route towards hydroxy acids opens up new avenues for the preparation of polyester building blocks.
- Fraaije, Marco W.,Martin, Caterina,Trajkovic, Milos
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- Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
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The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
- Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
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- C-C bond cleavage of cyclohexene oxide in the reaction with 1- aminoindoline
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The reaction of cyclohexene oxide with 1-aminoindoline under neat conditions gave a C-C bond-cleavage product of cyclohexene oxide as a dihydrazone and a 1,2-aminoalcohol-type product. No hydrazinoalcohol was obtained.
- Kiryu, Yoshimitu,Itoh, Satoshi,Kaneko, Kimiyoshi,Katayama, Hajime
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- Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase
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The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
- Rahimi, Mehran,Geertsema, Edzard M.,Miao, Yufeng,Van Der Meer, Jan-Ytzen,Van Den Bosch, Thea,De Haan, Pim,Zandvoort, Ellen,Poelarends, Gerrit J.
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- Syntheses of bifunctional compounds from cycloalkenes via ozonide intermediates
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The ozonolytic cleavage of cycloalkene in the presence of methyl pyruvate affords a tri-substituted ozonide. The resulted tri-substituted ozonide moiety contained three reactive centers (i.e, peroxide, ozonide ring proton and methoxycarbonyl group) which could be transformed to different functional groups under different conditions in good yields. It is a very efficient and versatile methodology to prepare the terminal differentiated compounds from symmetric cycloalkenes in two steps in high yields.
- Hon, Yung-Son,Yan, Jiann-Long
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- Catalytic Models of Tyrosinase: Reactivity Differences between Systems Based on Mono- and Binucleating Ligands
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A new tyrosinase model based on the binucleating ligand Lpy2 is synthesized and characterized. The ligand Lpy2 contains a combination of an imine and a pyridine function in the sidearms, which are bridged by a flexible alkyl spacer. As shown by UV/Vis and NMR spectroscopy, the Cu2Lpy2 complex catalyzed the conversion of the monophenol 2,4-di-tert-butylphenol (DTBP-H) into the o-quinone 3,5-di-tert-butylquinone (DTBQ) with a turnover number (TON) of 18. The dicopper complex of Lpy2 thus shows monophenolase activity that is comparable to that of the recently developed Lpy1 model of tyrosinase, which is based on a known mononucleating ligand (M. Rolff, J. Schottenheim, G. Peters, F. Tuczek, Angew. Chem. Int. Ed. 2010, 122, 6583). The electron-poor substrate 4-hydroxybenzoic acid methyl ester (MeBA-OH), in contrast, is converted by Cu2Lpy2 into the semiquinone. For both substrates, the oxygenation reactions were also conducted in a stoichiometric fashion to obtain information on the intermediates involved. For the substrate MeBA-OH, we detected a binuclear μ-catecholato copper(II) complex by high-resolution ESI mass spectrometry. These studies were complemented by investigations of deactivation mechanisms that could be invoked to explain the limitation of the TON. To this end, a bis-μ-hydroxido Lpy2 dicopper(II) complex as well as a semiquinone Lpy2 complex were prepared. Both complexes may represent decay products of the catalyst. A tyrosinase model based on the binucleating ligand Lpy2 was developed and characterized. The ligand Lpy2 contains a combination of an imine and a pyridine function in the sidearms that are bridged by a flexible alkyl spacer. The Cu2Lpy2 complex catalyzes the conversion of monophenol DTBP-H into the o-quinone DTBQ (TON = 18). An electron-poor substrate is converted into the semiquinone.
- Schottenheim, Julia,Gernert, Claus,Herzigkeit, Benjamin,Krahmer, Jan,Tuczek, Felix
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- Graft copolymers with polyamide backbones via combination of passerini multicomponent polymerization and controlled chain-growth polymerization
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We report a facile 'grafting from' approach to graft copolymers with polyamide backbones and controlled vinyl polymer or polyester side chains. Two polyamides with in situ-formed pendant bromide or hydroxyl groups were obtained by Passerini-based multicomponent polymerization. They were used respectively to initiate the atom-transfer radical polymerization of vinyl monomers or the ring-opening polymerization of lactones to generate two new types of graft copolymers. One of the important features of the method is that the pendant initiators are generated in situ from non-branching monomers, and they are linked to the polymer backbone by ester bonds. Therefore, the vinyl polymer side chains could be detached from the backbones, and their structures could thus be fully characterized. Moreover, multicomponent polymerization and atom-transfer radical polymerization can even be carried out in a one-pot manner. CSIRO 2014.
- Deng, Xin-Xing,Cui, Yang,Wang, Yao-Zong,Du, Fu-Sheng,Li, Zi-Chen
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- Continuous-flow synthesis of adipic acid from cyclohexene using hydrogen peroxide in high-temperature explosive regimes
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Safe only in a microreactor! The synthesis of adipic acid from cyclohexene by tungstic acid-catalyzed oxidation using hydrogen peroxide following the classical Noyori protocol can be accomplished in good yields with residence times as short as 20 min at 140 °C using a safe and scalable microreactor environment. Under these intensified conditions the use of a phase-transfer catalyst is not required. Copyright
- Damm, Markus,Gutmann, Bernhard,Kappe, C. Oliver
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- Products of the gas-phase reaction of OH radicals with cyclohexane: Reactions of the cyclohexoxy radical
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Products of the gas-phase reactions of OH radicals with cyclohexane and cyclohexane-d12 in the presence of NO have been investigated using gas chromatography with flame ionization detection, combined gas chromatography-mass spectrometry, and in situ direct air-sampling atmospheric pressure ionization tandem mass spectrometry (API-MS). Cyclohexanone and cyclohexyl nitrate (and their deuterated analogues) were identified and quantified, with formation yields of cyclohexanone and cyclohexyl nitrate from the cyclohexane reaction of 0.321 ± 0.035 and 0.165 ± 0.021, respectively, and with cyclohexanone-d10 and cyclohexyl nitrate-d11 formation yields from the cyclohexane-d12 reaction of 0.156 ± 0.017 and 0.210 ± 0.025, respectively. The remaining products must arise from the decomposition and/or isomerization reactions of the intermediate cyclohexoxy radical. API-MS analyses of the cyclohexane and cyclohexane-d12 reactions showed the formation of cyclohexanone and cyclohexyl nitrate (and their deuterated analogues), together with ion peaks attributed to HC(O)CH2CH2CH2CH2CH 2ONO2 (formed from NO addition to the HC(O)CH2CH2CH2CH2CH 2OO? radical formed after decomposition of the cyclohexoxy radical) and HC(O)CH2CH(OH)CH2CH2CHO (formed after isomerization of the HC(O)CH2CH2CH2CH2CH 2O? radical). No evidence for isomerization of the cyclohexoxy radical was obtained from the API-MS analyses. The reactions of the cyclohexoxy radical are discussed and the data extended to the reactions of the cyclopentoxy and cycloheptoxy radicals formed from cyclopentane and cycloheptane.
- Aschmann, Sara M.,Chew, Andrew A.,Arey, Janet,Atkinson, Roger
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- Exceptionally Facile Reduction of Carboxylic Esters to Aldehydes by Lithium Aluminum Hydride in the Presence of Diethylamine
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Both aliphatic and aromatic carboxylic esters are readily reduced to the corresponding aldehydes by lithium aluminum hydride in the presence of excess diethylamine in pentane in excellent yields at room temperature.
- Cha, Jin Soon,Kwon, Soon Sam
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- Oxidation of terminal diols using an oxoammonium salt: A systematic study
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A systematic study of the oxidation of a range of terminal diols is reported, employing the oxoammonium salt 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+ BF4-) as the oxidant. For substrates bearing a hydrocarbon chain of seven carbon atoms or more, the sole product is the dialdehyde. A series of post-oxidation reactions have been performed showing that the product mixture resulting from the oxidation step can be taken on directly to a subsequent transformation. For diols containing four to six carbon atoms, the lactone product is the major product upon oxidation. In the case of 1,2-ethanediol and 1,3-propanediol, when using a 1 : 0.5 stoichiometric ratio of substrate to oxidant, the corresponding monoaldehyde is formed which reacts rapidly with further diol to yield the acetal product. This is of particular synthetic value given both the difficulty of their preparation using other approaches and also their potential application in further reaction chemistry.
- Miller, Shelli A.,Bobbitt, James M.,Leadbeater, Nicholas E.
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- The formation of highly oxidized multifunctional products in the ozonolysis of cyclohexene
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The prompt formation of highly oxidized organic compounds in the ozonolysis of cyclohexene (C6H10) was investigated by means of laboratory experiments together with quantum chemical calculations. The experiments were performed in borosilicate glass flow tube reactors coupled to a chemical ionization atmospheric pressure interface time-of-flight mass spectrometer with a nitrate ion (NO3-)-based ionization scheme. Quantum chemical calculations were performed at the CCSD(T)-F12a/VDZ-F12//ωB97XD/aug-cc-pVTZ level, with kinetic modeling using multiconformer transition state theory, including Eckart tunneling corrections. The complementary investigation methods gave a consistent picture of a formation mechanism advancing by peroxy radical (RO2) isomerization through intramolecular hydrogen shift reactions, followed by sequential O2 addition steps, that is, RO2 autoxidation, on a time scale of seconds. Dimerization of the peroxy radicals by recombination and cross-combination reactions is in competition with the formation of highly oxidized monomer species and is observed to lead to peroxides, potentially diacyl peroxides. The molar yield of these highly oxidized products (having O/C > 1 in monomers and O/C > 0.55 in dimers) from cyclohexene ozonolysis was determined as (4.5 ± 3.8)%. Fully deuterated cyclohexene and cis-6-nonenal ozonolysis, as well as the influence of water addition to the system (either H2O or D2O), were also investigated in order to strengthen the arguments on the proposed mechanism. Deuterated cyclohexene ozonolysis resulted in a less oxidized product distribution with a lower yield of highly oxygenated products and cis-6-nonenal ozonolysis generated the same monomer product distribution, consistent with the proposed mechanism and in agreement with quantum chemical modeling.
- Rissanen, Matti P.,Kurtn, Theo,Sipil?, Mikko,Thornton, Joel A.,Kangasluoma, Juha,Sarnela, Nina,Junninen, Heikki,Jorgensen, Solvejg,Schallhart, Simon,Kajos, Maija K.,Taipale, Risto,Springer, Monika,Mentel, Thomas F.,Ruuskanen, Taina,Pet?j?, Tuukka,Worsnop, Douglas R.,Kjaergaard, Henrik G.,Ehn, Mikael
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- First stereoselective syntheses of (-)-siphonodiol and (-)- tetrahydrosiphonodiol, bioactive polyacetylenes from marine sponges
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The first stereoselective total syntheses of the bioactive marine polyacetylenes (-)-siphonodiol and (-)-tetrahydrosiphonodiol were achieved using highly convergent approaches based on optimized Cadiot-Chodkiewicz and sequential Sonogashira cross-coupling reactions.
- Lopez, Susana,Fernandez-Trillo, Francisco,Midon, Pilar,Castedo, Luis,Saa, Carlos
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- A Photorearrangement to Construct the ABDE Tetracyclic Core of Palau'amine
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A synthesis of the ABDE tetracyclic carbon core of palau'amine was achieved in 9 steps from commercial materials. The core's most notable feature, a highly strained trans cyclopenta[c]pyrrolidine, was obtained in high yield using a ring contraction strategy starting from a much less strained trans bicyclic lactam derivative that is accessible in only 7 steps.
- Aubert-Nicol, Samuel,Lessard, Jean,Spino, Claude
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- IBX amides: A new family of hypervalent iodine reagents
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Amides of 2-iodoxybenzoic acid (IBX amides, 1) are a new class of pentavalent iodine compounds with a pseudo-benziodoxole structure. These 2-iodoxybenzamides are useful reagents for the oxidation of alcohols, with a reactivity pattern similar to IBX (R=CH(CH3)CO2CH3 or CH(CH2Ph)CO2CH3 (in crystal structure shown)).
- Zhdankin, Viktor V.,Koposov, Alexey Y.,Netzel, Brian C.,Yashin, Nikolai V.,Rempel, Brian P.,Ferguson, Michael J.,Tykwinski, Rik R.
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- Periodic ethylene-vinyl alcohol copolymers via ADMET polymerization: Synthesis, characterization, and thermal property
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Periodic copolymers of ethylene and vinyl alcohol (EVA) were synthesized via acyclic diene metathesis (ADMET) polymerization of a series of structurally symmetric α,ω-diene monomers that containing two vinyl acetate (VAc) units, followed by exhaustive hydrogenation and subsequent hydrolysis. This synthetic methodology provided a new type of EVA copolymer with defined sequence and ever highest VA content via ADMET. These polymer samples were characterized by gel permeation chromatography (GPC), NMR, and matrix-assisted laser desorption/ionization time-of-fight mass spectroscopy (MALDI-TOF-MS). Thermal properties of EVAc and EVA copolymers were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). EVAc copolymers exhibited two-stage decompositions on TGA traces and displayed a glass transition on DSC thermograms. Meanwhile, the EVA copolymers showed glass transition stages and sharp melting peaks on DSC thermograms, with the T m values being comparable to that of high density polyethylene (HDPE).
- Li, Zi-Long,Lv, An,Li, Lei,Deng, Xin-Xing,Zhang, Li-Jing,Du, Fu-Sheng,Li, Zi-Chen
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- The ozonolytic cleavage of cycloalkenes in the presence of methyl pyruvate to yield the terminally differentiated compounds
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The ozonolytic cleavage of cycloalkenes in the presence of methyl pyruvate affords the trisubstituted ozonides. These ozonides possess triple reactive sites which could be converted to several terminally differentiated products via reduction or base treatment.
- Hon, Yung-Son,Yanb, Sann-Long
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- Synthesis of callyberynes A and B, polyacetylenic hydrocarbons from marine sponges
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(Matrix presented) Callyberynes A and B, polyacetylenic hydrocarbons from Callyspongia sp., have been synthesized for the first time using highly convergent approaches based on optimized Cadiot-Chodkiewicz (Alami, Vasella) and sequential Sonogashira cross-coupling reactions.
- Lopez, Susana,Fernandez-Trillo, Francisco,Castedo, Luis,Saa, Carlos
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- Acyl Radicals: the Relationship between Electron Spin Resonance Spectra, Structure, and Stability in a Family of ?-Radicals
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A series of saturated and unsaturated acyl radicals, RC.=O, have been generated in fluid solution, principally by the photolysis of di-t-butyl peroxide in the presence of the corresponding aldehyde.Most of th acyl radicals show well-resolved hyperfine splittings, and the values of a(Hβ( correlate with the n.m.r. coupling constants 3J(CHCHO) in the parent aldehyde.It is concluded that the acyl radicals and the corresponding aldehydes have similar structures.
- Davies, Alwyn G.,Sutcliffe, Roger
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- Butadiene hydroformylation to adipaldehyde with Rh-based catalysts: Insights into ligand effects
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Rh-catalyzed hydroformylation of butadiene to adipaldehyde is a promising alternative route for producing valuable C6 compounds such as adipic acid and hexamethylenediamine. Fundamental insights into reaction pathways, aimed at enhancing adipaldehyde yield, were obtained from temporal concentration profiles and in situ ReactIR studies of butadiene hydroformylation on Rh complexes at 80 °C and 14 bar syngas (molar CO/H2 = 1) pressure in a batch reactor. Specifically, the effects of operating conditions and eight commercially available ligands on activity and selectivity were systematically investigated. It was found that the adipaldehyde selectivity is independent of the ligand/Rh ratio, rhodium concentration, butadiene concentration and syngas pressure, but significantly dependent on the type of ligand used. For example, while the DIOP ligand provided an adipaldehyde yield of ~40% with butadiene as a substrate, the 6-DPPon ligand gave a maximum adipaldehyde yield of ~93% with 4-pentenal as substrate. Furthermore, the adipaldehyde selectivity correlates well with the natural bite angle of the various ligands. ReactIR studies suggest that the preferential formation of the stable rhodium η3-crotyl complex with the various Rh complexes may be the main reason for the low adipaldehyde selectivity.
- Yu, Si-min,Snavely, William K.,Chaudhari, Raghunath V.,Subramaniam, Bala
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- Oxidation by cobalt(III)acetate. Part 9. Effect of substituents on the oxidative Cleavage of glycols in acetic acid
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The kinetics of oxidative cleavage of glycols by obalt(III) acetate in acetic acid have been studied.The substrates examined include cis- and trans-cyclopentane- and cyclohexane-1,2-diols and their mono- and dimethyl derivatives.The rates were first-order in both cobalt(III)acetate and substrate in all cases.In the oxidation of five-membered ring diols, cis-diols were generally oxidized faster than the trans-isomers.Complex results were obtained in the case of six-membered ring diols.Thermodynamic parameters were calculated for all the substrates.A mechanism involving a bidente complex of cobalt(III) acetate dimer and glycol is sugge sted, except for the case of trans-cyclopentane-1,2-diols, for which a monodentate intermediate is proposed.
- Gunji, Tomokazu,Hirano, Masao,Morimoto, Takashi
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- Synthesis of Adipic Aldehyde by n-Selective Hydroformylation of 4-Pentenal
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Several phosphine and phosphite ligands were tested in the hydroformylation of 4-pentenal to adipic aldehyde, a versatile starting material for industrially very relevant compounds. By varying the ligand structure we were able to increase the selectivity toward adipic aldehyde to >95%. Additionally, two molecular structures of important catalytic intermediates [(bisphosphite)RhH(CO)2] and one structure of a previously unknown catalyst decomposition product were obtained. (Chemical Equation Presented).
- Mormul, Jaroslaw,Mulzer, Michael,Rosendahl, Tobias,Rominger, Frank,Limbach, Michael,Hofmann, Peter
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- Novel Tetraindoles and Unexpected Cycloalkane Indoles from the Reaction of Indoles and Aliphatic Dialdehydes
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The reaction of indoles with dialdehydes was studied for the first time. Mild reaction conditions using glacial acetic acid led to two novel kinds of reaction products: one designated as alkyl chain-connected tetraindoles and the other one as bis(indolyl)-substituted cycloalkane indoles. The suggested reaction pathways are discussed. The indole substituents of the cycloalkane indoles were either trans or cis orientated depending from the alkyl chain length.
- El-Sayed, Mardia Telep,Mahmoud, Kazem Ahmed,Heinemann, Frank W.,Hilgeroth, Andreas
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- Evidence for isomerizing hydroformylation of butadiene. A combined experimental and computational study
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The (DIOP)rhodium-catalyzed hydroformylation of butadiene has been shown to give among the highest selectivities for formation of adipaldehyde, which is useful for the synthesis of nylon. Herein, isomerizing hydroformylation is shown to be a mechanism that is partially responsible for this selectivity and density functional theory studies are used to reveal the detailed pathway for the requisite alkene isomerization.
- Maji, Tapan,Mendis, Camina H.,Thompson, Ward H.,Tunge, Jon A.
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- Toward the rhodium-catalyzed bis-hydroformylation of 1,3-butadiene to adipic aldehyde
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The effects of the ligand to metal ratio, temperature, syngas pressure, partial pressures of H2 and CO, and new ligand structures have been examined on 12 of the most reasonable products resulting from the rhodium-catalyzed low-pressure hydroformylation of 1,3-butadiene. The selectivity for the desired linear dihydroformylation product, 1,6-hexanedial (adipic aldehyde), is essentially independent of all of these reaction parameters, except for ligand structure. However, the reaction parameters do have a substantial effect on the selectivity for the products, resulting from the branched addition of the rhodium hydride to the carbon-carbon double bond. The optimum reaction parameters and ligand have resulted in a so far unprecedented maximum selectivity of 50% for adipic aldehyde.
- Smith, Stuart E.,Rosendahl, Tobias,Hofmann, Peter
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Read Online
- Aerobic Oxidation of Vicinal Diols Catalyzed by an Anderson-Type Polyoxometalate, [IMo6O24]5-
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An Anderson-type polyoxometalate, [IVIIMo6O24]5-, has been used as a catalyst for the aerobic oxidation at 80°C of vicinal diols (glycols). This is the first report on the use of such a polyoxometalate as an oxi
- Khenkin, Alexander M.,Neumann, Ronny
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- Synthesis of alkyl substituted α,β unsaturated γ lactones as potential antitumor agents
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A series of alkyl substituted di and monolactones including (E,E) 3,3 (alkanediylidene)bis[dihydro 2(3H) furanones] and the monolactones was synthesized by reaction of α (triphenylphosphoranylidene) γ butyrolactone with appropriate aldehydes. The reaction of this ylide with formaldehyde gave α methylene γ butyrolactone. These compounds were tested for antitumor activity as part of a study to determine the influence of β substituents and distance between alkylating sites on the antitumor activity of α,β unsaturated lactones. The testing was carried out in standard National Cancer Institute screens and the compounds possessed ED50 values of 16 to 110 μg/ml against cells derived from human carcinoma of the nasopharynx (KB) and were inactive against L1210 lymphoid leukemia in the mouse.
- Howie,Manni,Cassady
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- Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction
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The function of ammonium salts on the epoxidation performance over Ti-BEA zeolite was investigated in detail. Experiments of alkene epoxidation, side reactions of epoxide and decomposition of H2O2 with or without ammonium salts were designed, and the UV-Vis spectroscopy was employed to analyze the structure of Ti-hydroperoxo species. It is revealed that the ammonia (or amines) dissociated from the ammonium salt would chelate with the linear Ti-η1(OOH) species and form a bridged Ti-η2(OOH)-R species, which is more stable, more weaker in epoxide adsorption and acidity as well. Therefore, side reactions and H2O2 decomposition would be suppressed, and both alkene conversion and epoxide selectivity would be promoted simultaneously. On the other hand, the excessive NH3?H2O (NH3/Ti>1) or NaOH bond with the Ti-η2(OOH)-R species and generate salt-like Ti-η2(OO)-M+ species, resulting in the deactivation of Ti active center. While for ammonium salts, e.g. NH4Cl, the limited dissociation degree along with the acidic environment help the Ti active center to maintain in highly active. In short, this work provides a practical Ti active center tuning method for Ti-BEA zeolite, as well as a thorough understanding of its Ti-hydroperoxo species.
- Liang, Xiaohang,Liu, Dan,Luo, Yibin,Peng, Xinxin,Shu, Xingtian,Xia, Changjiu
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- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
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Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
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- Industrial preparation method of hexamethylenediamine
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The invention discloses an industrial preparation method of hexamethylenediamine, wherein the industrial preparation method comprises the following steps: 1) dissolving cyclohexene in a first organic solvent, carrying out electrocatalytic oxidation reaction in a reaction kettle, carrying out constant potential electrolysis to obtain a reaction solution, and carrying out reduced pressure distillation to obtain adipic dialdehyde; and 2) dissolving adipic dialdehyde in a second organic solvent, introducing ammonia gas and hydrogen, and carrying out reductive amination reaction under the action of a supported nickel catalyst to obtain the hexamethylenediamine. The reaction adopts an electrocatalytic oxidation mode, and the selectivity is controlled by utilizing electrode potential, so that the reaction is more accurate and sufficient, the product conversion rate is improved, and the product is easy to separate, clean and environment-friendly; according to the method, hexamethylenediamine can be prepared through rectification operation, the product conversion rate of the method reaches 98.70%, the total yield reaches 98.02%, the purity reaches 95.14%-98.13%, the requirements of industrial production are met, and the method has good application prospects in industry; in addition, raw materials and auxiliary materials are simple and easy to obtain, the price is low, the input cost is low, and the construction scale is not limited.
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Paragraph 0029-0030; 0033-0034; 0037-0038; 0041-0043
(2021/06/13)
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- SBA15-supported nano-ruthenium catalyst for the oxidative cleavage of alkenes to aldehydes under flow conditions
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SBA15-supported ruthenium nanoparticles were prepared and employed as catalytic system for the oxidative cleavage of olefins under flow conditions. Design of experiments was adopted to optimize the reaction parameters and was instrumental to develop a fast and robust method for producing aldehydes from alkenes. Utilizing a simple flow set-up, the process provided high conversions in only few minutes with 0.5% mol of ruthenium under mild reaction conditions and high flow rates.
- Di Michele, Alessandro,Giovagnoli, Stefano,Filipponi, Paolo,Venturoni, Francesco,Gioiello, Antimo
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- Phosphine ligand for butadiene hydroformylation reaction and preparation method thereof
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The invention discloses a bidentate phosphine ligand compound with a structure as shown in a general formula 1, a synthesis method of the bidentate phosphine ligand compound, and application of the phosphine ligand to promotion of metal catalysis of 1, 3-butadiene hydroformylation reaction.
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Paragraph 0124-0127
(2021/06/23)
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- Process for preparing adipic dialdehyde from cyclohexene
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The invention discloses a process for preparing adipic dialdehyde from cyclohexene. The preparation method comprises the following steps: respectively injecting a mixed solution and an ozone-containing mixed gas into a micro-channel reactor, and carrying out an oxidation reaction under reaction conditions to obtain adipic dialdehyde, wherein the mixed solution containing cyclohexene and a metal chloride catalyst. According to the method, a metal chloride catalyst is combined with ozone, so that cyclohexene is selectively oxidized into adipic dialdehyde, the defect that precious metal coordination compounds and sodium periodate need to be used in a cyclohexene oxidation reaction is overcome, substance transfer between two-phase materials is effectively enhanced by adopting a micro-channel reactor and utilizing efficient mass transfer and heat transfer efficiency in the micro-reactor, and the product selectivity can reach 93.5%.
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Paragraph 0053-0056; 0057-0063
(2020/06/02)
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- PROCESS FOR PRODUCING DIALDEHYDE
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PROBLEM TO BE SOLVED: To provide a process for producing dialdehyde in high yield. SOLUTION: Provided is a process for producing a dialdehyde, comprising the step of reacting a cyclic alkene with an oxidizing agent in the presence of a catalyst having mononuclear ruthenium immobilized on a catalyst carrier. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0025-0026; 0028-0029
(2020/05/16)
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- Selective TEMPO-Oxidation of Alcohols to Aldehydes in Alternative Organic Solvents
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The TEMPO-catalyzed oxidation of alcohols to aldehydes has emerged to one of the most widely applied methodologies for such transformations. Advantages are the utilization of sodium hypochlorite, a component of household bleach, as an oxidation agent and the use of water as a co-solvent. However, a major drawback of this method is the often occurring strict limitation to use dichloromethane as an organic solvent in a biphasic reaction medium with water. Previous studies show that dichloromethane cannot easily be substituted because a decrease of selectivity or inhibition of the reaction is observed by using alternative organic solvents. Thus, up to now, only a few examples are known in which after a tedious optimization of the reaction dichloromethane could be replaced. In order to overcome the current limitations, we were interested in finding a TEMPO-oxidation method in alternative organic solvents, which is applicable for various alcohol oxidations. As a result, we found a method for N-oxyl radical-catalyzed oxidation using sodium hypochlorite as an oxidation agent in nitriles as an organic solvent component instead of dichloromethane. Besides the oxidation of aromatic primary alcohols also aliphatic primary alcohols, secondary alcohols as well as dialcohols were successfully converted when using this method, showing high selectivity towards the carbonyl compound and low amounts of the acid side-product.
- Hinzmann, Alessa,Stricker, Michael,Busch, Jasmin,Glinski, Sylvia,Oike, Keiko,Gr?ger, Harald
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p. 2399 - 2408
(2020/04/29)
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- LIPID PRODRUGS OF JAK INHIBITORS AND USES THEREOF
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The present invention provides lymphatic system-directing lipid prodrugs, pharmaceutical compositions thereof, methods of producing such prodrugs and compositions, and methods of improving the bioavailability or other properties of a therapeutic agent that comprises part of the lipid prodrug. The present invention also provides methods of treating a disease, disorder, or condition such as those disclosed herein, comprising administering to a patient in need thereof a disclosed lipid prodrug or a pharmaceutical composition thereof.
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Paragraph 00627-00628
(2020/09/12)
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- LIPID PRODRUGS OF GLUCOCORTICOIDS AND USES THEREOF
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The present invention provides lymphatic system-directing lipid prodrugs, pharmaceutical compositions thereof, methods of producing such prodrugs and compositions, and methods of improving the bioavailability or other properties of a therapeutic agent that comprises part of the lipid prodrug. The present invention also provides methods of treating a disease, disorder, or condition such as those disclosed herein, comprising administering to a patient in need thereof a disclosed lipid prodrug or a pharmaceutical composition thereof.
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Paragraph 00620
(2020/09/12)
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- Novel method for synthesizing dialdehyde compound
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The invention provides a method for synthesizing a dialdehyde compound, and an acetal represented by the structural formula (I) and a Grignard reagent represented by the structural formula (II) are subjected to a coupling reaction and then hydrolyzed to obtain the dialdehyde compound, wherein the structural formula (I) and the structural formula (II) are described in the specification. The method has the advantages of high reaction activity, the reaction can be carried out even under the condition of room temperature, the reaction completed time is short, almost no other by-products are generated, no catalyst is required to be used, the reaction yield is high, and the reaction speed is fast. Moreover, the product purity is high, the dialdehyde compound with the purity of about 98% can be obtained after concentration, and no complex purification process is required.
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Paragraph 0077; 0079; 0081
(2020/07/23)
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- Method for preparing 1,6-adipaldehyde through selective oxidation of cyclohexene
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The invention discloses a method for preparing 1,6-adipaldehyde through selective oxidation of cyclohexene. A catalyst is a cobalt complex of an isosteviol derivative. The method comprises the steps as follows: adding a solvent, cyclohexene, a catalyst and a cocatalyst to a reaction kettle, introducing oxygen, keeping the pressure of the reaction kettle at 0.2-0.6 MPa, and conducting a reaction atthe temperature of 120-170 DEG C for 60-300 min to obtain 1,6-adipaldehyde. Compared with existing methods, the method has the advantages that free radicals produced through decomposition of the cocatalyst tert-butyl hydroperoxide act with oxygen to produce oxygen radicals, the catalyst cobalt complex of the isosteviol derivative acts with double bonds in cyclohexene, so that the reaction activity is higher, and activated double bonds and free radicals react to produce 1,6-adipaldehyde. The method is environmentally friendly, and 1,6-adipaldehyde is good in selectivity and high in yield.
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Paragraph 0020; 0028; 0030; 0035; 0037; 0041; 0043; 0050
(2019/03/08)
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- An Engineered Alcohol Oxidase for the Oxidation of Primary Alcohols
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Structure-guided directed evolution of choline oxidase has been carried out by using the oxidation of hexan-1-ol to hexanal as the target reaction. A six-amino-acid variant was identified with a 20-fold increased kcat compared to that of the wild-type enzyme. This variant enabled the oxidation of 10 mm hexanol to hexanal in less than 24 h with 100 % conversion. Furthermore, this variant showed a marked increase in thermostability with a corresponding increase in Tm of 20 °C. Improved solvent tolerance was demonstrated with organic solvents including ethyl acetate, heptane and cyclohexane, thereby enabling improved conversions to the aldehyde by up to 30 % above conversion for the solvent-free system. Despite the evolution of choline oxidase towards hexan-1-ol, this new variant also showed increased specific activities (by up to 100-fold) for around 50 primary aliphatic, unsaturated, branched, cyclic, benzylic and halogenated alcohols.
- Heath, Rachel S.,Birmingham, William R.,Thompson, Matthew P.,Taglieber, Andreas,Daviet, Laurent,Turner, Nicholas J.
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p. 276 - 281
(2019/01/04)
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- Visible-light mediated C-C bond cleavage of 1,2-diols to carbonyls by cerium-photocatalysis
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We describe a photocatalytic method for the cleavage of vicinal diols to aldehydes and ketones. The reaction is catalyzed by blue light and a cerium-catalyst and the scope includes aryl as well as alkyl substituted diols. The simple protocol which works under air and at room temperature enables the valorization of abundant diols.
- Schwarz, Johanna,K?nig, Burkhard
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supporting information
p. 486 - 488
(2019/01/10)
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- Intermediate of telaprevir and preparation method thereof
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The invention discloses an intermediate of telaprevir and a preparation method thereof. The invention specifically discloses a method for preparing a compound shown in the formula 6. The method comprises that a compound shown in the formula 7 or 5 undergoes a reaction under the action of an acid aqueous solution at a temperature of 50-100 DEG C. The preparation method is easy to operate, realizesa low cost, has a high yield, produces a product with high purity and is easy to industrialize.
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Paragraph 0130; 0131
(2018/03/26)
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- Selective mono addition of aryllithiums to dialdehydes by micromixing
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Micromixing enables highly selective mono addition of aryllithiums to dialdehydes. Because the unchanged formyl group in the products can be used for further transformations, the present approach serves as a powerful method for protecting-group-free synthesis.
- Nagaki, Aiichiro,Yamashita, Hiroki,Takahashi, Yusuke,Ishiuchi, Satoshi,Imai, Keita,Yoshida, Jun-Ichi
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supporting information
p. 71 - 73
(2018/01/26)
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- Preparation method and application of brphinsted acidic ionic liquid using periodate as anion as well as method for preparing alpha,omega-dialdehyde
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The invention relates to the field of fine chemical industry, and concretely provides an application of brphinsted acidic ionic liquid using periodate as an anion as well as a preparation method thereof. The invention provides a method for preparing alpha,omega-dialdehyde. The method comprises the following steps: in a condition of a solution, cycloolefin and/or alkylene oxide and an oxidizing agent are contacted, transparent liquid with white deposition is obtained, transparent liquid and white deposition are obtained by separation, wherein the oxidizing agent is brphinsted acidic ionic liquid using periodate as the anion. The brphinsted acidic ionic liquid using periodate as the anion can be used as an oxidizing agent for carrying out an oxidation reaction is provided for the first time, and the method has the advantages of simple and easily operated process, green and environmental protection, cleaning, and repeated recovery and utilization of the oxidizing agent.
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Paragraph 0120; 0121
(2017/05/12)
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- A preparation method of the hexamethylene diamine
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The invention discloses a preparation method of hexamethylenediamine. The method is used for preparing 1, 6-hexamethylenediamine by virtue of carrying out ammoniation and catalytic hydrogenation on 1, 6-adipaldehyde. The method is simple in process, low in cost, high in yield, low in energy consumption and free from industrial three wastes.
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- Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
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A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides were thus obtained in yields of 59–81 % and enantioselectivities of up to 94:6 e.r. (98:2 e.r. if the intermediate dialkylborane is purified by crystallization). A rapid access to enantiomerically pure (+)-rodocaine is also described. The use of other arenesulfonyl radical traps enables enantioselective hydroallylation, hydrosulfanylation, and hydrobromination reactions with yields of 71–86 %.
- Meyer, Daniel,Renaud, Philippe
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supporting information
p. 10858 - 10861
(2017/08/30)
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- Synthesis and characterisation of cycloruthenated benzhydrazone complexes: Catalytic application to selective oxidative cleavage of olefins to aldehydes
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A simple and convenient method to synthesise new air-stable cyclometalated ruthenium(ii) complexes from the reaction of p-substituted acetophenone benzhydrazide ligands and [RuHCl(CO)(AsPh3)3] has been described. The complexes have been characterised by various methods, including elemental analysis, FT-IR, NMR (1H and 13C) and UV-vis. The molecular structures of complexes 3 and 4 have been determined by singlecrystal X-ray diffraction analysis which indicates the tridentate coordination mode of the ligand and the presence of a distorted octahedral geometry around the ruthenium ion. The complexes have been found to be a highly active catalytic system in the selective oxidative cleavage of a wide range of alkenes and alkynes in the presence of NaIO4 as an oxidant. Notably, the desired aldehyde products were obtained with high conversions and yields using 0.5 mol% catalyst loading within 30 min at room temperature. Furthermore, the influence of reaction parameters such as solvents, oxidants, temperature and catalyst loading was also investigated.
- Manikandan, Thimma Sambamoorthy,Ramesh, Rengan,Semeril, David
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p. 97107 - 97115
(2016/10/25)
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- Synthesis, structural characterization and catalysis of ruthenium(II) complexes based on 2,5-bis(2′-pyridyl)pyrrole ligand
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Treatment of the 2,5-bis(2′-pyridyl)pyrrolato (PDP-) anion with {Ru(COD)Cl2}n in THF readily yielded [Ru(PDP)(COD)Cl] (1) in almost quantitative yield. Anion metathesis of 1 in organic solvent by NO3- and OTf- (OTf- = triflato) gave [Ru(PDP)(COD)(NO3)] (2) and [Ru(PDP)(COD)(OTf)] (3), and in aqueous solution by BF4- and PF6- afforded aqueous complexes [Ru(PDP)(COD)(H2O)](BF4) (4+·BF4-) and [Ru(PDP)(COD)(H2O)](PF6) (4+·PF6-), respectively. Treatment of 1 with PhICl2 in CH2Cl2 afforded 5 with halogenated pyrrole. These complexes exhibit similar structure, including one Ru(ii) atom, one 2,5-bis(2′-pyridyl)pyrrole and one monodentate anion or aqua ligand. Each Ru(ii) tightly binds to three adjacent coplanar sites of PDP- ligand to form a meridional configuration. Complex 1 with NaIO4 as the oxidant in EtOAc-CH3CN-H2O (ratio = 3 : 1 : 2) proved to be highly effective in the catalytic oxidation of olefins to carbonyl products.
- Zhong, Yi-Qing,Xiao, Hui-Qiong,Yi, Xiao-Yi
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p. 18113 - 18119
(2016/11/25)
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- Cyclopentene process for the preparation of formaldehyde
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The invention provides a cyclopentenecarboxaldehyde preparation method, and belongs to the technical field of pharmacy. The method comprises: performing ring opening reaction on cyclohexene oxide under the effect of sodium periodate and sulfuric acid, so as to prepare adipaldehyde; and performing cyclization on adipaldehyde under the effect of L-proline and other catalysts, so as to convert adipaldehyde into cyclopentenecarboxaldehyde. The provided method is simple in operation, is capable of obtaining the high-quality product at a high yield and is suitable for industrialized production.
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Paragraph 0007; 0057; 0058
(2017/03/08)
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- METHODS OF PRODUCING 6-CARBON MONOMERS FROM 8-CARBON COMPOUNDS
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This document describes biochemical pathways for producing 6-hydroxyhexanoic acid using a monooxygenase to form a 7-hydroxyoctanoate intermediate, which can be converted to 6-hydroxyhexanoate using a polypeptide having monooxygenase, secondary alcohol dehydrogenase, or esterase activity. 6-hydroxyhexanoic acid can be enzymatically converted to adipic acid, caprolactam, 6-aminohexanoic acid, hexamethylenediamine or 1,6-hexanediol. This document also describes recombinant hosts producing 6-hydroxyhexanoic acid as well as adipic acid, caprolactam, 6-aminohexanoic acid, hexamethylenediamine and 1,6-hexanediol.
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Page/Page column 16; 54
(2016/06/14)
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- Synthesis, complexation behavior and catalytic performance of chelating bisphosphite ligands based on 9,10-brigded 9,10-dihydroanthracenes in Rh catalyzed hydroformylation of 4-pentenal
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In the present work the modular synthesis of new chelating bisphosphite ligands based on 9,10-brigded 9,10-dihydroanthracenes as ligand backbones is presented. The complexation behavior of these ligands in rhodium metal complexes as well as mechanistic studies of the preformation step of the rhodium-catalysed hydroformylation is investigated. Ratio of coordination isomers in the Rh complexes of these ligands has been determined using NMR based calculation technique. Modular synthesis route was established allowing for a variety of ligands to be synthesized in a standard procedure The new ligands were tested in the hydroformylation of 4-pentenal under optimized conditions to give adipic aldehyde a promising starting material for the polyamide nylon-6,6. Ligand L3 showed the best selectivity towards adipic aldehyde with selectivity of 10.2/1 n/iso aldehyde.
- Bond?i?, Bojan P.,Rominger, Frank,Hofmann, Peter
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p. 472 - 477
(2016/08/05)
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- Two tandem multicomponent reactions for the synthesis of sequence-defined polymers
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Multicomponent polymerizations have become powerful tools for the construction of sequence-defined polymers. Although the Passerini multicomponent reaction has been widely used in the synthesis of sequence-defined polymers, the tandem usage of the Passerini multicomponent reaction and other multicomponent reactions in one-pot for the synthesis of sequence-defined polymers has not been developed until now. In this contribution, we report the tandem usage of the Passerini three-component reaction and the three-component amine-thiol-ene conjugation reaction in one pot for the synthesis of sequence-defined polymers. The Passerini reaction between methacrylic acid, adipaldehyde, and 2-isocyanobutanoate was carried out, affording a new molecule containing two alkene units. Subsequently, an amine and a thiolactone were added to the reaction system, whereupon the three-component amine-thiol-ene conjugating reaction occurred to yield a sequence-defined polymer. This method offers more rapid access to sequence-defined polymers with high molecular diversity and complexity.
- Yang, Lu,Zhang, Ze,Cheng, Bofei,You, Yezi,Wu, Decheng,Hong, Chunyan
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p. 1734 - 1740
(2015/11/02)
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- Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols
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Cu/nitroxyl catalysts have been identified that promote highly efficient and selective aerobic oxidative lactonization of diols under mild reaction conditions using ambient air as the oxidant. The chemo- and regioselectivity of the reaction may be tuned by changing the identity of the nitroxyl cocatalyst. A Cu/ABNO catalyst system (ABNO = 9-azabicyclo[3.3.1]nonan-N-oxyl) shows excellent reactivity with symmetrical diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl) displays excellent chemo- and regioselectivity for the oxidation of less hindered unsymmetrical diols. These catalyst systems are compatible with all classes of alcohols (benzylic, allylic, aliphatic), mediate efficient lactonization of 1,4-, 1,5-, and some 1,6-diols, and tolerate diverse functional groups, including alkenes, heterocycles, and other heteroatom-containing groups.
- Xie, Xiaomin,Stahl, Shannon S.
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supporting information
p. 3767 - 3770
(2015/04/14)
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- Alkane oxidation with peroxides catalyzed by cage-like copper(II) silsesquioxanes
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Isomeric cage-like tetracopper(II) silsesquioxane complexes [(PhSiO1.5)12(CuO)4(NaO0.5)4] (1a), [(PhSiO1.5)6(CuO)4(NaO0.5)4(PhSiO1.5)6] (1b) and binuclear complex [(PhSiO1.5)10(CuO)2(NaO0.5)2] (2) have been studied by various methods. These compounds can be considered as models of some multinuclear copper-containing enzymes. Compounds 1a and 2 are good pre-catalysts for the alkane oxygenation with hydrogen peroxide in air in an acetonitrile solution. Thus, the 1a-catalyzed reaction with cyclohexane at 60°C gave mainly cyclohexyl hydroperoxide in 17% yield (turnover number, TON, was 190 after 230 min and initial turnover frequency, TOF, was 100 h-1). The alkyl hydroperoxide partly decomposes in the course of the reaction to afford the corresponding ketone and alcohol. The effective activation energy for the cyclohexane oxygenation catalyzed by compounds 1a and 2 is 16 ± 2 and 17 ± 2 kcal mol-1, respectively. Selectivity parameters measured in the oxidation of linear and branched alkanes and the kinetic analysis revealed that the oxidizing species in the reaction is the hydroxyl radical. The analysis of the dependence of the initial reaction rate on the initial concentration of cyclohexane led to a conclusion that hydroxyl radicals attack the cyclohexane molecules in proximity to the copper reaction centers. The oxidations of saturated hydrocarbons with tert-butylhydroperoxide (TBHP) catalyzed by complexes 1a and 2 exhibit unusual selectivity parameters which are due to the steric hindrance created by bulky silsesquioxane ligands surrounding copper reactive centers. Thus, the methylene groups in n-octane have different reactivities: the regioselectivity parameter for the oxidation with TBHP catalyzed by 1a is 1:10.5:8:7. Furthermore, in the oxidation of methylcyclohexane the position 2 relative to the methyl group of this substrate is noticeably less reactive than the corresponding positions 3 and 4. Finally, the oxidation of trans-1,2-dimethylcyclohexane with TBHP catalyzed by complexes 1a and 2 proceeds stereoselectively with the inversion of configuration. The 1a-catalyzed reaction of cyclohexane with H216O2 in an atmosphere of 18O2 gives cyclohexyl hydroperoxide containing up to 50% of 18O. The small amount of cyclohexanone, produced along with cyclohexyl hydroperoxide, is 18O-free and is generated apparently via a mechanism which does not include hydroxyl radicals and incorporation of molecular oxygen from the atmosphere.
- Vinogradov, Mikhail M.,Kozlov, Yuriy N.,Bilyachenko, Alexey N.,Nesterov, Dmytro S.,Shul'pina, Lidia S.,Zubavichus, Yan V.,Pombeiro, Armando J. L.,Levitsky, Mikhail M.,Yalymov, Alexey I.,Shul'pin, Georgiy B.
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p. 187 - 199
(2015/02/19)
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- A highly efficient catalyst for selective oxidative scission of olefins to aldehydes: Abnormal-NHC-Ru(II) complex in oxidation chemistry
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The utility and selectivity of the catalyst [Ru(COD)(L1)Br2] (1) bearing a fused π-conjugated imidazo[1,2-a][1,8]naphthyridine-based abnormal N-heterocyclic carbene ligand L1 is demonstrated toward selective oxidation of C=C bonds to aldehydes and C=C bonds to α-diketones in an EtOAc/CH3CN/H2O solvent mixture at room temperature using a wide range of substrates, including highly functionalized sugar- and amino acid-derived compounds.
- Daw, Prosenjit,Petakamsetty, Ramu,Sarbajna, Abir,Laha, Siladitya,Ramapanicker, Ramesh,Bera, Jitendra K.
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supporting information
p. 13987 - 13990
(2015/01/08)
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- Self-assembly of an azobenzene-containing polymer prepared by a multi-component reaction: Supramolecular nanospheres with photo-induced deformation properties
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In this article, we have synthesized a polymer containing regulated azobenzene groups by one-pot multi-component polymerization (MCP) based on Passerini reaction, and investigated its self-assembly behavior and photo-induced deformation properties. We found that this molecule can form spherical structures with sizes ranging from hundreds of nanometers to several micrometers when dissolved in THF. NMR and FTIR studies indicate that there are associated hydrogen bonds among the molecules in the aggregates, which are responsible for the formation of the nanospheres. By controlling the stirring rate as the THF suspension is dropped into water, the nanospheres can be sorted according to their size. In this way, we have obtained nanospheres with relatively uniform diameter. When irradiated by UV light in the aqueous medium, the nanospheres tend to aggregate into large clusters, while in dry state they are ready to merge into island-like structures, showing a good photo-induced deformation property.
- Wang, Shuai,Zhang, Ning,Ge, Xiaopeng,Wan, Yingbo,Li, Xiaohong,Yan, Li,Xia, Yijun,Song, Bo
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p. 4833 - 4839
(2014/07/07)
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- Synthesis of dibromoolefins via a tandem ozonolysis-dibromoolefination reaction
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In this Letter we outline the synthesis of a variety of dibromoolefins (DBOs) from a series of alkenes by coupling an oxidative cleavage and a reaction with a phosphorous ylide. This approach strategically avoids isolation of reactive aldehyde intermediates and presents one of the few examples coupling carbon-carbon bond formation with ozonolysis.
- Brown, Brenna Arlyce,Veinot, Jonathan G.C.
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supporting information
p. 792 - 795
(2013/02/25)
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- Peptide-catalyzed stereoselective conjugate addition reactions generating all-carbon quaternary stereogenic Centers
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A powerful catalyst: Quaternary stereogenic centers adjacent to tertiary stereocenters were formed with high diastereoselectivities and enantioselectivities in conjugate addition reactions between aldehydes and β,β-disubstituted nitroolefins by using a peptidic catalyst (see scheme). γ-Amino acids and heterocyclic compounds bearing quaternary stereogenic centers are easily accessible from the products. Copyright
- Kastl, Robert,Wennemers, Helma
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supporting information
p. 7228 - 7232
(2013/07/26)
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- Fe-catalyzed one-pot oxidative cleavage of unsaturated fatty acids into aldehydes with hydrogen peroxide and sodium periodate
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A one-pot method has been developed for the oxidative cleavage of internal alkenes into aldehydes by using 0.5mol % of the nonheme iron complex [Fe(OTf)2(mix-bpbp)] (bpbp=N,N'-bis(2-picolyl)-2,2'-bipyrrolidine) as catalyst and 1.5equivalents of hydrogen peroxide and 1equivalent of sodium periodate as oxidants. A mixture of diastereomers of the chiral bpbp ligand can be used, thereby omitting the need for resolution of its optically active components. The cleavage reaction can be performed in one pot within 20h and under ambient conditions. Addition of water after the epoxidation, acidification and subsequent pH neutralization are crucial to perform the epoxidation, hydrolysis, and subsequent diol cleavage in one pot. High aldehyde yields can be obtained for the cleavage of internal aliphatic double bonds with cis and trans configuration (86-98 %) and unsaturated fatty acids and esters (69-96 %). Good aldehyde yields are obtained in reactions of trisubstituted and terminal alkenes (62-63 %). The products can be easily isolated by a simple extraction step with an organic solvent. The presented protocol involves a lower catalyst loading than conventional methods based on Ru or Os. Also, hydrogen peroxide can be used as the oxidant in this case, which is often disproportionated by second- and third-row metals. By using only mild oxidants, overoxidation of the aldehyde to the carboxylic acid is prevented. Copyright
- Spannring, Peter,Yazerski, Vital,Bruijnincx, Pieter C. A.,Weckhuysen, Bert M.,Klein Gebbink, Robertus J. M.
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p. 15012 - 15018
(2013/11/06)
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- Characterization of a new enzyme oxidizing ω-amino group of aminocarboxyric acid, aminoalcohols and amines from Phialemonium sp. AIU 274
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A new enzyme exhibiting oxidase activity for ω-aminocarboxylic acids, ω-aminoalcohols, monoamines and diamines was found from a newly isolated fungal strain, Phialemonium sp. AIU 274. The enzyme also oxidized aromatic amines, but not l- and d-amino acids. The Vmax/Km value for hexylamine was higher than those for 6-aminoalcohol and 6-aminhexanoic acid in the aliphatic C6 substrates. In the aliphatic amines, the higher Vmax/Km values were obtained by the longer carbon chain amines. Thus, the enzyme catalyzed oxidative deamination of the ω-amino group in a wide variety of the ω-amino compounds and preferred medium- and long-chain substrates. The oxidase with such broad substrate specificity was first reported here. The enzyme contained copper, and the enzyme activity was strongly inhibited by isoniazid, iproniazid and semicarbazide, but not by clorgyline and pargyline. The enzyme was composed of two identical subunits of 75 kDa.
- Isobe, Kimiyasu,Sasaki, Tomoko,Aigami, Yuusuke,Yamada, Miwa,Kishino, Shigenobu,Ogawa, Jun
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- Acid-catalyzed aldol-Meerwein-Ponndorf-Verley-etherification reactions - Access to defined configured quaternary stereogenic centers
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A novel asymmetric aldol-reduction-etherification process of aliphatic enolizable aldehydes is described. The intermediately formed aldol adducts - β-hydroxyaldehydes - were reduced and transformed into the corresponding 1,3-diol ethers by external secondary alcohols at the same time. Thus, with the help of chiral secondary alcohols an access to optically active 1,3-diol ether is given. Furthermore, asymmetric cross-aldol-Meerwein-Ponndorf reactions of enolizable aldehydes can also be realized under these reaction conditions.
- Seifert, Andrea,Rohr, Kerstin,Mahrwald, Rainer
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p. 1137 - 1144
(2012/02/15)
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