- A new insight into the oxidation of cyclododecane with hydrogen peroxide in the presence of iron-substituted polyoxotungstates
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The catalytic homogeneous oxidation of cyclododecane with hydrogen peroxide in the presence of tetrabutylammonium salts of iron-substituted Keggin-type polyoxotungstates of general formula (TBA)4HzXW 11Fe(H2O)O39-nH2O (where X = P, Si, B, and z = 0-2) is described. In the reaction conditions reported, the corresponding alcohol, ketone, and hydroperoxide are obtained as the main reaction products. The catalytic activity of the anions with phosphorous, silicon, and boron is compared in different reaction conditions. These catalytic oxidation reactions seem to be radical processes, since they are totally inhibited in the presence of I2, a well-known radical scavenger. Thieme Stuttgart.
- Santos, Isabel C. M. S.,Sim?es, Mário M. Q.,Balula, M. Salete S.,Neves, M. Gra?a P. M. S.,Cavaleiro, José A. S.,Cavaleiro, Ana M. V.
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- A useful and environmentally benign synthetic protocol for dethiolization by employing vanadium pentoxide catalyzed oxidation of ammonium bromide by hydrogen peroxide
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A wide variety of thioacetals and thioketals can be cleaved chemoselectively in presence of olefin and aromatic ring as well as other protecting groups to carbonyl compounds by employing V2O5 catalyzed oxidation of ammonium bromide by H2O2 in CH2Cl2-H2O solvent system; mild conditions, high selectivity, good yield, and no side products such as bromination or oxidation are some of the major advantages.
- Mondal, Ejabul,Bose, Gopal,Sahu, Priti Rani,Khan, Abu T.
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- Conversion of Ketals to Ketones by Nitrogen Dioxide in the Presence of Silica Gel
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Nitrogen dioxide transforms ketals to ketones in the presence of silica gel under neutral, anhydrous and mild conditions.
- Nishiguchi, Takeshi,Ohosima, Tatsuya,Nishida, Akiko,Fujisaki, Shizuo
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- A highly efficient procedure for regeneration of carbonyl groups from their corresponding oxathioacetals and dithioacetals using sodium nitrite and acetyl chloride in dichloromethane
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A wide variety of oxathioacetals 1 as well as dithioacetals 2 can be chemoselectively deprotected to the corresponding carbonyl compounds 3 in good yields by employing NaNO2-AcCl and H2O in CH2Cl2 at 0°C to room temperature. Some of the major advantages of this procedure are: mild conditions, easy to handle, highly chemoselective and efficient, high yields and inexpensive reagents. In addition, no acetylation occurs at the hydroxyl group nor chlorination takes place at the double bond.
- Khan, Abu T.,Mondal, Ejabul,Sahu, Priti R.
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- Dynamic Imine Chemistry at Complex Double Emulsion Interfaces
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Interfacial chemistry provides an opportunity to control dynamic materials. By harnessing the dynamic covalent nature of imine bonds, emulsions are generated in situ, predictably manipulated, and ultimately destroyed along liquid-liquid and emulsion-solid interfaces through simple perturbation of the imine equilibria. We report the rapid production of surfactants and double emulsions through spontaneous in situ imine formation at the liquid-liquid interface of oil/water. Complex double emulsions with imine surfactants are stable to neutral and basic conditions and display dynamic behavior with acid-catalyzed hydrolysis and imine exchange. We demonstrate the potential of in situ imine surfactant formation to generate complex surfactants with biomolecules (i.e., antibodies) for biosensing applications. Furthermore, imine formation at the emulsion-solid interface offers a triggered payload release mechanism. Our results illustrate how simple, dynamic interfacial imine formation can translate changes in bonding to macroscopic outputs.
- Zentner, Cassandra A.,Anson, Francesca,Thayumanavan,Swager, Timothy M.
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- An expedient and efficient method for the cleavage of dithioacetals to the corresponding carbonyl compounds using organic ammonium tribromide (OATB)
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A variety of dithioacetals of aldehydes or ketones 1 can be easily cleaved into the parent carbonyl compounds 2 at 0-5°C in very high yields by employing organic ammonium tribromides such as cetyltrimethyl-ammonium tribromide (CetTMATB) or tetrabutylammonium tribromide (TBATB) in dichloromethane.
- Mondal,Bose,Khan
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- Sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker) (Lepidoptera: Lymantriidae)
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Two distinct electroantennographycally active (EAG-active) components, A and B, and a weakly active component C were found in a solvent extract from virgin females of the Ishigaki strain of the tussock moth, Orgyia postica (Walker). Components A, B, and C were found in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively. Components A, B, and C were identified as (6Z,9Z,11S,12S)-11,12-epoxyhenicosa-6,9-diene [(11S,12S)-1: posticlure], (6Z)-henicos-6-en-11-one (2), and (6Z,9Z)-henicosa-6,9-diene (3), respectively. Component B was absent in the extract from the Okinawa strain, in which components A and C were present at 2.0 and 1.5 ng/female respectively. (11S,12S)-1 and the racemic mixture showed attractiveness for both the Okinawa and Ishigaki strains, whereas (11R,12R)-1 did not. The addition of 2 significantly reduced the trap catches with (11S,12S)-1 on the Okinawa strain which lacked 2, while there was no significant inhibitory effect on the Ishigaki strain. The addition of 3 to (11S,12S)-1 did not significantly affect trap catches at Ishigaki or Okinawa. This confirmed that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1.
- Wakamura, Sadao,Arakaki, Norio,Yamamoto, Masanobu,Hiradate, Syuntaro,Yasui, Hiroe,Kinjo, Kunio,Yasuda, Tetsuya,Yamazawa, Hiroyuki,Ando, Tetsu
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- Enolate and Other Carbon Nucleophile Alkylation Reactions Using 1,2-Cyclic Sulfates as Terminal Epoxide Equivalents
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Enolates of esters and amides as well as α-sulfonyl-, α-cyano-, and α-phosphonyl-substituted anions react with cyclic sulfate 1 to give hydroxylated products arising from nucleophilic attack, on this terminal epoxide equivalent, at the primary carbon.
- Hoye, Thomas R.,Crawford, Khushrav B.
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- Kinetics of the MnO4- oxidation of anionic surfactant (sodiumdodecyl sulphate): Evidence for the formation of soluble colloidal MnO2
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A conventional spectrophotometric technique was used to study the oxidation of SDS by permanganate in a perchloric acid medium. It was observed that the reaction proceeded in two stages (fast first stage followed by a relatively slow second stage). Plots of log(absorbance) versus time deviate from linearity. The kinetic and spectroscopic data are consistent with the formation of soluble colloidal MnO2. The first-order kinetics with respect to [SDS] at low concentrations shifted to second-order at higher concentrations. The kinetics of oxidation is first-order with respect to both [MnO4-] and [HClO4]. The oxidation rate was decreased by the addition of P2O74- and Mn(II) ions. Second-step oxidation is not a true path for the oxidation of the Mn(IV)-SDS reaction. In the presence of Mn(II) (a reaction product), the MnO4- oxidation of SDS becomes more complicated, and an exact dependence on [Mn(II)] can not be estimated. Different activation parameters have been evaluated. Mechanisms consistent with the kinetic data have been proposed and discussed. The -O-SO3- group is responsible for the oxidative degradation of SDS by MnO4-.
- Raju,Khan, Zaheer
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- Pyridinium poly(hydrogen fluoride)-assisted cleavage of acetals and ketals
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Acetals, including ketals, were smoothly cleaved by the action of pyridinium poly(hydrogen fluoride) without addition of water or an alcohol in an anhydrous solvent.
- Watanabe, Yutaka,Kiyosawa, Youko,Tatsukawa, Akiko,Hayashi, Minoru
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- Discovery of Anti-TNBC Agents Targeting PTP1B: Total Synthesis, Structure-Activity Relationship, in Vitro and in Vivo Investigations of Jamunones
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Twenty-three natural jamunone analogues along with a series of jamunone-based derivatives were synthesized and evaluated for their inhibitory effects against breast cancer (BC) MDA-MB-231 and MCF-7 cells. The preliminary structure-activity relationship revealed that the length of aliphatic side chain and free phenolic hydroxyl group at the scaffold played a vital role in anti-BC activities and the methyl group on chromanone affected the selectivity of molecules against MDA-MB-231 and MCF-7 cells. Among them, jamunone M (JM) was screened as the most effective anti-triple-negative breast cancer (anti-TNBC) candidate with a high selectivity against BC cells over normal human cells. Mechanistic investigations indicated that JM could induce mitochondria-mediated apoptosis and cause G0/G1 phase arrest in BC cells. Furthermore, JM significantly restrained tumor growth in MDA-MB-231 xenograft mice without apparent toxicity. Interestingly, JM could downregulate phosphatidylinositide 3-kinase (PI3K)/Akt pathway by suppressing protein-tyrosine phosphatase 1B (PTP1B) expression. These findings revealed the potential of JM as an appealing therapeutic drug candidate for TNBC.
- Hu, Caijuan,Li, Guoxun,Mu, Yu,Wu, Wenxi,Cao, Bixuan,Wang, Zixuan,Yu, Hainan,Guan, Peipei,Han, Li,Li, Liya,Huang, Xueshi
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p. 6008 - 6020
(2021/05/06)
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- Cassis and Green Tea: Spontaneous Release of Natural Aroma Compounds from β-Alkylthioalkanones
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In depth headspace analysis of the slow degradation of β-alkylthioalkanones in ambient air led to the discovery of a novel δ-cleavage pathway, by which β-mercaptoketones are released. Since β-mercaptoketones are potent natural aroma compounds occurring in many fruits, herbs and flowers, the discovery of an enzyme-independent molecular precursor for this class of high-impact molecules is of practical importance. Moreover, the formation of β-diketones and aldehydes by concomitant oxidation at the α-sulfur-position enhances the versatility of this class of aroma precursors. A mechanistic model is proposed which suggests that the oxidative degradation occurs through a novel Pummerer-type rearrangement of initially formed persulfoxides.
- B?ttig, Sarah,Egger, Timothy,Gey, Olga,Bochet, Christian G.,Flachsmann, Felix
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- Selective Production of Linear Aldehydes and Alcohols from Alkenes using Formic Acid as Syngas Surrogate
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Performing carbonylation without the use of carbon monoxide for high-value-added products is an attractive yet challenging topic in sustainable chemistry. Herein, effective methods for producing linear aldehydes or alcohols selectively with formic acid as both carbon monoxide and hydrogen source have been described. Linear-selective hydroformylation of alkenes proceeds smoothly with up to 88 % yield and >30 regioselectivity in the presence of single Rh catalyst. Strikingly, introducing Ru into the system, the dual Rh/Ru catalysts accomplish efficient and regioselective hydroxymethylation in one pot. The present processes utilizing formic acid as syngas surrogate operate simply under mild condition, which opens a sustainable way for production of linear aldehydes and alcohols without the need for gas cylinders and autoclaves. As formic acid can be readily produced via CO2 hydrogenation, the protocols represent indirect approaches for chemical valorization of CO2.
- Chen, Junjun,Hua, Kaimin,Liu, Xiaofang,Deng, Yuchao,Wei, Baiyin,Wang, Hui,Sun, Yuhan
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p. 9919 - 9924
(2021/05/31)
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- A Strategy for Accessing Aldehydes via Palladium-Catalyzed C?O/C?N Bond Cleavage in the Presence of Hydrosilanes
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We report the catalytic reduction of both active esters and amides by selective C(acyl)?X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)?N and C(acyl)?O bond cleavage. Carboxylic acid C(acyl)?O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)?O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)?N cleavage under the same reaction conditions.
- He, Zhanyu,Liu, Tingting,Ru, Junxiang,Wang, Yulin,Wang, Zijia,Zeng, Zhuo
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p. 5794 - 5800
(2020/12/01)
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- PROCESS FOR THE PREPARATION OF A FATTY ALDEHYDE
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The present invention relates to a process for the preparation of a fatty aldehyde which process comprises (a) providing a fatty acid, and (b) contacting the fatty acid with a zerovalent metal catalyst to reduce the fatty acid to the fatty aldehyde, wherein the zerovalent metal catalyst is in the form of solid particles.
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Page/Page column 8; 9
(2021/01/23)
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- Direct conversion of terminal alkenes to aldehydes via ozonolysis reaction in rotating zigzag bed
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In this study, continuous ozonolysis of terminal alkenes in a rotating zigzag bed was developed. Rotating zigzag bed is a new type high gravity unit relative to the previous rotating packed bed and can intensify mass transfer remarkably. The rotating zigzag bed takes advantage of centrifugal force to mix liquid and gas phase effectively. The H2O in acetone acts as an in situ reducing agent for the carbonyl oxide intermediate, providing aldehydes directly from the reaction mixture. Critical factors were investigated and achieved optimum reaction conditions. Under these conditions, the yields of series aldehydes ranged from 72.3 to 95.8percent. The discrepancy in product yields among different olefin substrates likely originates from the electronic stability of the carbonyl oxide intermediate, which is longer lived for aryl olefines with electron donor group and longer carbon chain alkene (CnH2n, n ≥ 10).
- Liang, Zhengyong,Wei, Tong,Xie, Jun,Li, Hua,Liu, Hui
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p. 2379 - 2384
(2020/05/25)
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- Catalytic isomerization-hydroformylation of olefins by rhodium salicylaldimine pre-catalysts
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A series of new Schiff-base rhodium(i) water-soluble complexes (C1-C3), were prepared and characterized. These complexes served as catalyst precursors for the hydroformylation of 1-octene and resulted in excellent substrate conversions (>98%) with 100% chemoselectivities to aldehydes, under mild conditions. Notably, good regioselectivities towards branched aldehydes were observed clearly demonstrating the catalysts’ ability in thermodynamically favoured isomerization followed by hydroformylation (n/iso ratio ranging between 0.7-1.2). Interestingly, catalystC1uniquely promoted contra-thermodynamic isomerization of 2-octene to 1-octene with up to 50% conversion. The efficacy of catalystC1was further evaluated in the hydroformylation of longer chain olefins (C10-C12), methyl acrylate, ethyl acrylate and styrene. The catalyst displayed conversions >99% with the long chain substrates and much lower conversions with the acrylates. These water-soluble (pre)catalysts were recycled up to three times with no significant loss in catalytic activity and selectivity. Mercury poisoning tests were conducted and the experiments revealed that the conversion of the substrates into aldehydes was due to molecular active catalysts and not as a result of colloidal particles that could have formedin situthrough the decomposition of the catalyst precursor. Finally, the molecular catalyst responsible for activity was established using preliminary computational calculations.
- Sekoto, Pamela N.,Magengenene, Tseliso M.,Matsinha, Leah C.,Tia, Richard,Darkwa, James,Makhubela, Banothile C. E.
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p. 8751 - 8762
(2020/06/08)
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- Iron-Catalyzed Aerobic Oxidation of Alcohols: Lower Cost and Improved Selectivity
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An aerobic oxidation reaction of alcohols toward aldehydes or ketones using catalytic amounts of Fe(NO3)3·9H2O, 4-OH-TEMPO, and NaCl has been developed. Compared with the former catalytic system with TEMPO developed in this group, the new protocol using 4-OH-TEMPO, which is much cheaper on an industrial scale, accomplished the transformation with a higher selectivity, especially for aliphatic alcohols toward aldehydes. α,β-Unsaturated alkynals or alkynones can be efficiently synthesized from propargyl alcohols, which has been much less studied in the literature.
- Jiang, Xingguo,Liu, Jinxian,Ma, Shengming
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p. 825 - 835
(2019/05/02)
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- Enzymatic One-Step Reduction of Carboxylates to Aldehydes with Cell-Free Regeneration of ATP and NADPH
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The direct generation of aldehydes from carboxylic acids is often a challenging synthetic task but undoubtedly attractive in view of abundant supply of such feedstocks from nature. Though long known, biocatalytic carboxylate reductions are at an early stage of development, presumably because of their co-factor requirement. To establish an alternative to whole-cell-based carboxylate reductions which are limited by side reactions, we developed an in vitro multi-enzyme system that allows for quantitative reductions of various carboxylic acids with full recycling of all cofactors and prevention of undesired over-reductions. Regeneration of adenosine 5′-triphosphate is achieved through the simultaneous action of polyphosphate kinases from Meiothermus ruber and Sinorhizobium meliloti and β-nicotinamide adenine dinucleotide 2′-phosphate is reduced by a glucose dehydrogenase. Under these conditions and in the presence of the carboxylate reductases from Neurospora crassa or Nocardia iowensis, various aromatic, heterocyclic and aliphatic carboxylic acids were quantitatively reduced to the respective aldehydes.
- Strohmeier, Gernot A.,Eitelj?rg, Inge C.,Schwarz, Anna,Winkler, Margit
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p. 6119 - 6123
(2019/04/13)
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- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
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Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
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supporting information
p. 10164 - 10167
(2018/09/13)
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- Hydrodeoxygenation of Fatty Acids, Triglycerides, and Ketones to Liquid Alkanes by a Pt–MoOx/TiO2 Catalyst
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Various supported metal catalysts are screened for hydrogenation of lauric acid and 2-octanone as model reactions for the transformation of biomass-derived oxygenates to liquid alkanes (biofuels) in a batch reactor under solvent-free conditions. Among the catalysts tested, Pt and MoOx co-loaded on TiO2 (Pt–MoOx/TiO2) shows the highest yields of n-alkanes for both of the reactions. Pt–MoOx/TiO2 selectively catalyzes the hydrodeoxygenation of various fatty acids and triglycerides to n-alkanes without C?C bond cleavage under 50 bar H2 and shows higher turnover numbers than the catalysts in the literature. Pt–MoOx/TiO2 is effective also for the hydrodeoxygenation of various ketones to the corresponding alkanes. In situ IR study of the reaction of adsorbed acetone under H2 suggests that the high activity of Pt–MoOx/TiO2 is attributed to the cooperation between Pt and Lewis acid sites of the MoOx/TiO2 support.
- Kon, Kenichi,Toyao, Takashi,Onodera, Wataru,Siddiki,Shimizu, Ken-Ichi
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p. 2822 - 2827
(2017/07/28)
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- Characterization of Carboxylic Acid Reductases as Enzymes in the Toolbox for Synthetic Chemistry
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Carboxylic acid reductase enzymes (CARs) meet the demand in synthetic chemistry for a green and regiospecific route to aldehydes from their respective carboxylic acids. However, relatively few of these enzymes have been characterized. A sequence alignment with members of the ANL (Acyl-CoA synthetase/ NRPS adenylation domain/Luciferase) superfamily of enzymes shed light on CAR functional dynamics. Four unstudied enzymes were selected by using a phylogenetic analysis of known and hypothetical CARs, and for the first time, a thorough biochemical characterization was performed. Kinetic analysis of these enzymes with various substrates shows that they have a broad but similar substrate specificity. Electron-rich acids are favored, which suggests that the first step in the proposed reaction mechanism, attack by the carboxylate on the α-phosphate of adenosine triphosphate (ATP), is the step that determines the substrate specificity and reaction kinetics. The effects of pH and temperature provide a clear operational window for the use of these CARs, whereas an investigation of product inhibition by NADP+, adenosine monophosphate, and pyrophosphate indicates that the binding of substrates at the adenylation domain is ordered with ATP binding first. This study consolidates CARs as important and exciting enzymes in the toolbox for sustainable chemistry and provides specifications for their use as a biocatalyst.
- Finnigan, William,Thomas, Adam,Cromar, Holly,Gough, Ben,Snajdrova, Radka,Adams, Joseph P.,Littlechild, Jennifer A.,Harmer, Nicholas J.
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p. 1005 - 1017
(2017/03/27)
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- Sequential reactions from catalytic hydroformylation toward the synthesis of amino compounds
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Different families of new amino compounds were efficiently synthesized, through optimized sequential processes, involving rhodium catalyzed hydroformylation as the key step. The selection of appropriate hydroformylation catalytic systems and reaction conditions allowed obtaining aldehydes derived from several n-alkyl olefins, cholest-4-ene and 3-vinyl-1H-indole, which were subsequently transformed, in one-pot, in to α-amino acids via hydroformylation/Strecker reaction, and in to tertiary amines via hydroaminomethylation, with excellent yields.
- Almeida, Ana R.,Carrilho, Rui M.B.,Peixoto, Andreia F.,Abreu, Artur R.,Silva, Artur,Pereira, Mariette M.
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supporting information
p. 2389 - 2395
(2017/04/03)
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- Method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on polyether pyrrolidine salt ion liquid
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The invention relates to a method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on polyether pyrrolidine salt ion liquid. A two-phase catalytic system is used herein and comprises polyether pyrrolidine salt ion liquid having indoor temperature liquid-solid phase change characteristics, a rhodium catalyst, diphosphine ligand, a reaction substrate alkene and a reaction product aldehyde; liquid/liquid two-phase hydroformylation is carried under certain reaction temperature and synthetic gas pressure, the rhodium catalyst is recycled through simple two-phase separation after reacting, the rhodium catalyst can be recycled tens of times, there is no significant decrease in catalytic activity and selectivity, TOF value of this system reaches 260-2000 h, catalytic circulatory accumulative TON value is up to higher than 34000, regioselectivity of the normal aldehyde is up to 96-98%, and rhodium loss is just 0.05-0.15%.
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Paragraph 0027; 0074; 0079-0080
(2017/06/02)
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- Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic Acids
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Oxidation from alcohols to carboxylic acids, a class of essential chemicals in daily life, academic laboratories, and industry, is a fundamental reaction, usually using at least a stoichiometric amount of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidation technology of alcohols to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amount each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcohols (also aldehydes) in high yields at room temperature. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished.
- Jiang, Xingguo,Zhang, Jiasheng,Ma, Shengming
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supporting information
p. 8344 - 8347
(2016/07/26)
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- A functionalized phosphine merit preparation of ionic liquids and its application in the hydroformylation reaction
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The invention relates to synthesis of first-class phosphorus functionalized polyether alkyl guanidinium ionic liquid, and an application of the first-class phosphorus functionalized polyether alkyl guanidinium ionic liquid in a homogeneous catalytic reaction. The functionalized ionic liquid of such class can be easily prepared by an ion exchange reaction between the polyether alkyl guanidinium ionic liquid and sulfonic acid type water soluble phosphine ligand. The designed phosphorus functionalized ionic liquid can be applied to organic reactions, including hydroformylation, hydroesterification, hydrocarboxylation and catalytic hydrogenation under the catalyzing of a transition metal; the dosage of the ionic liquid used in the catalytic reaction can be decreased; the activity of the catalytic reaction can be improved; a catalyst can be separated and cycled simply and conveniently.
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Paragraph 0074; 0075; 0076
(2017/11/08)
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- Transformation of methyl laurate into lauryl alcohol over a Ru-Sn-Mo/C catalyst by using zerovalent iron and water as an in situ hydrogen source
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Hydrogenation and hydrogenolysis reactions, which are used in the chemical industry for the synthesis of organic compounds, are very expensive operations because of the need for facilities that can liquefy, transport, and store the hydrogen produced through steam reforming of natural gas. We have therefore developed a novel approach for hydrogenation that does not require the use of high-cost facilities. Using this, zerovalent iron (Fe) and water (H2O) are introduced as an in situ hydrogen donor system for the transformation of methyl laurate into lauryl alcohol over a Ru-based catalyst. This combination of a Ru-Sn-Mo/C catalyst with a Fe/H2O system showed significantly higher transformation rates for the conversion of methyl laurate into lauryl alcohol than a conventional reaction system that uses pressurized hydrogen. The reason for this is that the new system produces lauric acid as an intermediate during the reaction, which is more efficiently hydrogenized into lauryl alcohol over the Ru-Sn-Mo/C catalyst. The Fe/H2O system played two important roles: a hydrogen source for the hydrogenation reaction and a catalyst for the generation of lauric acid by methyl laurate hydrolysis.
- Sagata, Kunimasa,Hirose, Mina,Hirano, Yoshiaki,Kita, Yuichi
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- An: In situ approach to preparing Ni2P/SiO2 catalyst under mild conditions and its performance for the deoxygenation of methyl laurate to hydrocarbons
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Ni2P/SiO2 was in situ prepared from Ni/SiO2via a phosphorization process using a dodecane solution containing triphenylphosphine (TPP) as the phosphorus source on a fixed-bed reactor. The influence of the phosphorization condition (nominal P/Ni molar ratio, temperature, WHSV of TPP and atmosphere) on the structure of the phosphorized samples was investigated. The sample structure was characterized by means of XRD, TEM, ICP-AES, TGA, N2 sorption, and FT-IR and magnetic property. It was found that the phosphorization of metallic Ni to Ni2P was promoted by increasing the phosphorization temperature and nominal P/Ni molar ratio and decreasing the WHSV of TPP. The phosphorization rate was much faster in the H2 atmosphere than the N2 one, ascribed to the formation of reactive H atoms on the Ni atoms that facilitated the cleavage of the P-C bond in PPT releasing more reactive PH3/P. To prepare the well-crystallized Ni2P/SiO2 in the H2 atmosphere, the minimum temperature (250 °C) and nominal P/Ni ratio (0.67) were necessary. Also, the Ni2P crystallite size in Ni2P/SiO2 was determined by the Ni one in Ni/SiO2, and no sintering took place during the phosphorization even at 400 °C. It is worth stating that there was a carbonaceous deposit formed on the in situ prepared catalysts, which was harmful for the catalyst activity for the deoxygenation of methyl laurate to hydrocarbons. The phosphorization condition greatly affected the performance of the resulting catalysts. On the whole, the Ni2P/SiO2 catalyst with good performance was prepared under a suitable phosphorization condition (i.e., 300 °C, nominal P/Ni ratio of 0.75, TPP WHSV of 0.5 h-1, and H2 atmosphere). Under the reaction conditions of 340 °C, 3.0 MPa, methyl laurate WHSV of 5 h-1 and H2/methyl laurate molar ratio of 25, it gave the conversion of methyl laurate and the total selectivity for C11 and C12 hydrocarbons higher than 98% and 96% during 100 h, respectively, exhibiting good stability. Finally, we propose a mechanism for the phosphorization of Ni/SiO2.
- Chen, Jixiang,Han, Mengmeng,Zhao, Sha,Pan, Zhengyi,Zhang, Zhena
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p. 3938 - 3949
(2016/06/13)
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- A Remarkably Simple Class of Imidazolium-Based Lipids and Their Biological Properties
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A series of imidazolium salts bearing two alkyl chains in the backbone of the imidazolium core were synthesized, resembling the structure of lipids. Their antibacterial activity and cytotoxicity were evaluated using Gram-positive and Gram-negative bacteria and eukaryotic cell lines including tumor cells. It is shown that the length of alkyl chains in the backbone is vital for the antibiofilm activities of these lipid-mimicking components. In addition to their biological activity, their surface activity and their membrane interactions are shown by film balance and quartz crystal microbalance (QCM) measurements. The structure-activity relationship indicates that the distinctive chemical structure contributes considerably to the biological activities of this novel class of lipids. Lipids! A series of imidazolium salts bearing two alkyl chains in the backbone were synthesized, resembling the structure of lipids. The biological activity resulting from their surface activity and membrane interaction are shown (see figure), which were determined by the alkyl chain length.
- Wang, Da,Richter, Christian,Rühling, Andreas,Drücker, Patrick,Siegmund, Daniel,Metzler-Nolte, Nils,Glorius, Frank,Galla, Hans-Joachim
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p. 15123 - 15126
(2015/11/02)
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- Rhodium versus iridium catalysts in the controlled tandem hydroformylation-isomerization of functionalized unsaturated fatty substrates
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The hydroformylation of 10-undecenitrile (1) and related unsaturated fatty substrates (H2C=CH(CH2)7CH2R; R=CO2Me, CH2Br, CHO) has been studied with rhodium, iridium, ruthenium, and palladium biphephos catalysts. The reactions proceeded effectively with all four systems, with high selectivities for the linear aldehyde (ratio of linear/branched aldehydes=99:1). The biphephos-bis[chloro(cyclooctadiene)iridium] system showed a non-optimized hydroformylation turnover frequency (TOFHF) of 770h-1 that was only approximately 5times lower than that of the rhodium-based system (TOFHF=3320h-1); the palladium and ruthenium biphephos systems were less active (TOFHF=210 and 310h-1, respectively). Upon recycling, remarkable productivities were achieved in both cases (TON≈58-000mol(1/1-int)-mol(Ir)-1 and 250-000mol(1/1-int)-mol(Rh)-1, in which int=internal olefin). Competitive isomerization of terminal to internal olefins occurred with these catalysts. Iridium biphephos systems allowed slightly better control of the distribution of the internal isomers than the rhodium biphephos catalyst, with higher ratios of 9-/8-undecenitrile (1-int). Place your bets now: Iridium-biphephos catalysts are highly effective in the controlled tandem isomerization-hydroformylation of 10-undecenitrile and related functionalized unsaturated fatty substrates.
- Ternel, Jrmy,Couturier, Jean-Luc,Dubois, Jean-Luc,Carpentier, Jean-Franois
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p. 513 - 520
(2015/03/04)
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- Mild and direct conversion of esters to morpholine amides using diisobutyl(morpholino)aluminum: Application to efficient one-pot synthesis of ketones and aldehydes from esters
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Morpholine amide intermediates, which are easily prepared by aminolysis of various esters with diisobutyl(morpholino)aluminum, react with organolithium and reducing agents (DIBALH or LDBMA) without isolation of the aminolysis intermediates to give ketones in 83-95% yields and aldehydes quantitatively.
- Jeon, Ah Ram,Kim, Min Eai,Park, Jae Kyo,Shin, Won Kyu,An, Duk Keun
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p. 4420 - 4424
(2014/06/10)
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- Ultrasound-assisted solventless synthesis of amines by in situ oxidation/reductive amination of benzyl halides
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Ultrasound-assisted solventless oxidation/reductive amination of benzyl halides was developed as a facile, efficient, and environmental friendly method toward N-alkylated amines. Aldehydes were formed in situ by oxidation of organic halides with N-methylmorpholine N-oxide (NMO), followed by direct reductive amination with amines using sodium borohydride and montmorillonite K-10 catalyst as the reducing system. This green and simple procedure enables N-alkylated amines to be prepared in good to excellent yields with high selectivity of the monoalkylation. This journal is the Partner Organisations 2014.
- Khumraksa, Bannarak,Phakhodee, Wong,Pattarawarapan, Mookda
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p. 20454 - 20458
(2014/06/09)
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- ALDEHYDE-SELECTIVE WACKER-TYPE OXIDATION OF UNBIASED ALKENES
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This disclosure is directed to methods of preparing organic aldehydes, each method comprising contacting a terminal olefin with an oxidizing mixture comprising: (a) a dichloro-palladium complex; (b) a copper complex; (c) a source of nitrite; under aerobic reaction conditions sufficient to convert at least a portion of the terminal olefin to an aldehyde.
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Page/Page column 0140-0149; 0155-0164; 0166-0168
(2014/10/29)
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- Promotional effect of Fe on performance of Ni/SiO2 for deoxygenation of methyl laurate as a model compound to hydrocarbons
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Ni/SiO2, Fe/SiO2 and bimetallic FeNi/SiO2 catalysts with different Fe/Ni weight ratios were prepared by incipient-wetness impregnation method for the deoxygenation of methyl laurate to hydrocarbons. It was found that a suitable amount of Fe enhanced the activity of Ni/SiO2 for the deoxygenation of methyl laurate, and FeNi(0.25)/SiO2 with a Fe/Ni weight ratio of 0.25 showed the best activity. Moreover, the addition of Fe to Ni/SiO2 significantly promoted the hydrodeoxygenation pathway to produce more C12 hydrocarbon and suppressed the activity for C-C hydrogenolysis. The effect of Fe on the performance of Ni/SiO2 is ascribed the formation of the NiFe alloy particles, particularly with the Fe-enriched surface at low Fe content, and the existence of oxygen vacancies in Fe oxides. A mechanism is proposed to explain the promoting effect of Fe, which involves the synergism between iron sites with strong oxophilicity and nickel sites with high ability to activate hydrogen. Besides, the effect of reaction conditions and catalyst stability were also investigated.
- Yu, Xinbin,Chen, Jixiang,Ren, Tianyu
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p. 46427 - 46436
(2015/01/09)
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- PROCESS FOR PREPARING C10 to C30 ALCOHOLS
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The present invention provides a process for preparing C10 to C30 alcohols, comprising the following steps: (i) reacting aliphatic, non-cyclic C10 to C30 olefins with N2O to obtain an oxidation reaction product comprising a C10 to C30 carbonyl; (ii) reducing at least part of the C10 to C30 carbonyls in the oxidation reaction product to the corresponding C10 to C30 alcohols, wherein the aliphatic, non-cyclic C10 to C30 olefins are reacted with the N2O by in step (i): (i-a) providing a liquid olefin feed comprising aliphatic, non-cyclic C10 to C30 olefins; (i-b) providing an oxidant feed comprising at least 5% by volume of N2O, based on the total oxidant feed; and (i-c) contacting the liquid olefin feed and the oxidant feed in a reactor at a temperature in the range of from 150 to 500 C and a pressure in the range of from 10 to 300 bar. In another aspect the invention provides a process or producing surfactant compounds and a method of treating a crude oil containing formation.
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Page/Page column 23; 26
(2014/10/18)
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- Reduction of nitriles into aldehydes using a TMDS/V(O)(OiPr)3 reducing system
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A simple and convenient method for the chemoselective reduction of nitriles into aldehydes using a 1,1,3,3-tetramethyldisiloxane (TMDS)/ triisopropoxyvanadium(V) oxide reducing system is described. Aromatic as well as aliphatic nitriles are reduced into the corresponding aldehydes in moderate to good yields.
- Laval, Stéphane,Dayoub, Wissam,Pehlivan, Leyla,Métay, Estelle,Delbrayelle, Dominique,Mignani, Gérard,Lemaire, Marc
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- Hexameric resorcinarene capsule is a bronsted acid: Investigation and application to synthesis and catalysis
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Molecular capsules have attracted interest as simple enzyme mimetics and several examples of catalytic transformations in water-soluble metal-ligand based systems have been reported. This is not the case for hydrogen-bond based molecular capsules, which in contrast can be employed in organic solvents. We describe herein our investigations of such a system: The resorcin[4]arene hexamer is one of the largest hydrogen bond-based self-assembled capsules and has been studied intensively due to its ready availability. We present evidence that the capsule acts as a reasonably strong Bronsted acid (pK a approximately 5.5-6). This finding explains the capsule's high affinity toward tertiary amines that are protonated and therefore encounter cation-π interactions inside the cavity. We were able to translate this finding into a first synthetic application: A highly substrate-selective Wittig reaction. We also report that this property renders the capsule an efficient enzyme-like catalyst for substrate selective diethyl acetal hydrolysis.
- Zhang, Qi,Tiefenbacher, Konrad
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supporting information
p. 16213 - 16219
(2013/11/19)
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- Aldehyde-selective wacker-type oxidation of unbiased alkenes enabled by a nitrite co-catalyst
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Breaking the rules: Reversal of the high Markovnikov selectivity of Wacker-type oxidations was accomplished using a nitrite co-catalyst. Unbiased aliphatic alkenes can be oxidized with high yield and aldehyde selectivity, and several functional groups are tolerated. 18O-labeling experiments indicate that the aldehydic O atom is derived from the nitrite salt. Copyright
- Wickens, Zachary K.,Morandi, Bill,Grubbs, Robert H.
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supporting information
p. 11257 - 11260
(2013/11/06)
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- Rhodium-catalyzed tandem isomerization/hydroformylation of the bio-sourced 10-undecenenitrile: Selective and productive catalysts for production of polyamide-12 precursor
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The hydroformylation of 10-undecenenitrile (1) - a substrate readily prepared from renewable castor oil - in the presence of rhodium-phosphane catalysts systems is reported. The corresponding linear aldehyde (2) can be prepared in high yields and regioselectivities with a (dicarbonyl)rhodium acetoacetonate-biphephos [Rh(acac)(CO)2-biphephos] catalyst. The hydroformylation process is accompanied by isomerization of 1 into internal isomers of undecenenitrile (1-int); yet, it is shown that the Rh-biphephos catalyst effectively isomerizes back 1-int into 1, eventually allowing high conversions of 1/1-int into 2. Recycling of the catalyst by vacuum distillation under a controlled atmosphere was demonstrated over 4-5 runs, leading to high productivities up to 230,000 mol (2)×mol (Rh)-1 and 5,750 mol (2)×mol (biphephos)-1. Attempted recycling of the catalyst using a thermomorphic multicomponent solvent (TMS) phase-separation procedure proved ineffective because the final product 2 and the Rh-biphephos catalyst were always found in the same polar phase. Auto-oxidation of the linear aldehyde 2 into the fatty 10-cyano-2-methyldecanoic acid (5) proceeds readily upon exposure to air at room temperature, opening a new effective entry toward polyamide-12. Copyright
- Ternel, Jeremy,Couturier, Jean-Luc,Dubois, Jean-Luc,Carpentier, Jean-Francois
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p. 3191 - 3204
(2013/12/04)
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- Effects of phosphorus substituents on reactions of α- alkoxyphosphonium salts with nucleophiles
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The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph3P with Grignard reagents was observed to take place in the presence of O2 to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments. A dramatic change in the reactivity of an α-alkoxyphosphonium salt toward nucleophiles is observed due to the steric and electronic nature of the phosphine substituents. By changing the type of phosphorus substituents, the reaction pathway can be controlled to proceed selectively by substitution or a new radical reaction (see scheme; OTf=trifluoromethansulfonate, TMS=trimethylsilyl, o-tol=tolyl). Copyright
- Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Sawama, Yoshinari,Maegawa, Tomohiro,Fujioka, Hiromichi
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p. 11423 - 11432
(2012/11/07)
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- Efficient reduction of esters to aldehydes through iridium-catalyzed hydrosilylation
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Trumping DIBALH: A new method for reduction of esters to aldehydes through silyl acetal intermediates involves a single-step hydrosilylation catalyzed by a readily available iridium complex, [{Ir(coe)2Cl}2] (see scheme; coe=cyclooctene). The low catalyst loading, mild reaction conditions, high conversions, and broad substrate scope make this method a superior alternative to ester reduction using DIBALH.
- Cheng, Chen,Brookhart, Maurice
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p. 9422 - 9424
(2012/10/30)
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- An iron catalyzed regioselective oxidation of terminal alkenes to aldehydes
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Fe(BF4)2·6H2O with pyridine-2,6-dicarboxylic acid and PhIO can efficiently catalyze the regioselective oxidation of terminal alkene derivatives to aldehydes under mild and benign reaction conditions.
- Chowdhury, Abhishek Dutta,Ray, Ritwika,Lahiri, Goutam Kumar
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supporting information; experimental part
p. 5497 - 5499
(2012/07/01)
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- Selective oxidation of terminal aryl and aliphatic alkenes to aldehydes catalyzed by iron(iii) porphyrins with triflate as a counter anion
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[Fe(Por)CF3SO3] (Por = porphyrin dianion) can efficiently catalyze selective oxidation of terminal aryl alkenes and aliphatic alkenes to aldehydes in good to high yields under mild conditions.
- Chen, Guo-Qiang,Xu, Zhen-Jiang,Zhou, Cong-Ying,Che, Chi-Ming
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supporting information; experimental part
p. 10963 - 10965
(2011/11/06)
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- A novel synthetic method for the preparation of aliphatic aldehydes from the corresponding carboxylic acids
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A novel synthetic method for the preparation of aliphatic aldehydes from the corresponding carboxylic acids via 1,3-dimethylbenzimidazolium salts is provided. 1,3-Dimethylbenzimidazolium salts were rapidly reduced with sodium/ethanol and then hydrolyzed with hydrochloric acid to obtain aliphatic aldehydes, in which the 1,3-dimethylbenzimidazolium salts can be readily achieved from the corresponding carboxylic acids. The mechanism for the reductive reaction of 1,3-dimethylbenzimidazolium salts with sodium/ethanol was discussed.
- Guo, Yuan,Lu, Zhenhuan,Yao, Libo,Shi, Zhen
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experimental part
p. 489 - 492
(2012/01/05)
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- Regioselective ω-hydroxylation of medium-chain n-alkanes and primary alcohols by CYP153 enzymes from Mycobacterium marinum and Polaromonas sp. strain JS666
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The oxofunctionalization of saturated hydrocarbons is an important goal in basic and applied chemistry. Biocatalysts like cytochrome P450 enzymes can introduce oxygen into a wide variety of molecules in a very selective manner, which can be used for the synthesis of fine and bulk chemicals. Cytochrome P450 enzymes from the CYP153A subfamily have been described as alkane hydroxylases with high terminal regioselectivity. Here we report the product yields resulting from C5-C12 alkane and alcohol oxidation catalyzed by CYP153A enzymes from Mycobacterium marinum (CYP153A16) and Polaromonas sp. (CYP153A P. sp.). For all reactions, byproduct formation is described in detail. Following cloning and expression in Escherichia coli, the activity of the purified monooxygenases was reconstituted with putidaredoxin (CamA) and putidaredoxin reductase (CamB). Although both enzyme systems yielded primary alcohols and α,ω-alkanediols, each one displayed a different oxidation pattern towards alkanes. For CYP153A P. sp. a predominant ω-hydroxylation activity was observed, while CYP153A16 possessed the ability to catalyze both ω-hydroxylation and α,ω- dihydroxylation reactions.
- Scheps, Daniel,Honda Malca, Sumire,Hoffmann, Helen,Nestl, Bettina M.,Hauer, Bernhard
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scheme or table
p. 6727 - 6733
(2011/11/30)
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- A nitric acid-assisted carbon-catalyzed oxidation system with nitroxide radical cocatalysts as an efficient and green protocol for selective aerobic oxidation of alcohols
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The incorporation of nitroxide radicals into a nitric acid-assisted carbon-catalyzed oxidation system (NACOS) afforded a highly efficient, widely applicable, non-metallic approach for the selective aerobic oxidations of alcohols. Without any solvent, this novel protocol has the ability to oxidize various primary alcohols to their corresponding aldehydes with selectvities as high as 99% at full conversions, with only 0.1 mol% of nitroxide radicals and 4.5 wt% of activated carbon under mild conditions (temperatures as low as 50°C and atmospheric pressure). The performances of several stable nitroxide radicals have been compared. The effects of nitric acid concentration, activated carbon loading, and temperature have been studied for the oxidation of benzyl alcohol. The enhanced NACOS represents a greener and more efficient fundamental chemical process, due to its use of molecular oxygen as an oxidant, and its solvent-free nature.
- Kuang, Yongbo,Rokubuichi, Hodaka,Nabae, Yuta,Hayakawa, Teruaki,Kakimoto, Masa-Aki
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experimental part
p. 2635 - 2642
(2010/12/25)
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- Remarkable effect of phosphine on the reactivity of O,P-acetal - Efficient substitution reaction of O,P-acetal
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The structure and electronic nature of the phosphine have a significant influence on not only the formation, but also the subsequent transformation of O,P-acetals. The O,P-acetals generated from tris(o-tolyl)phosphine [(o-tol) 3P] underwent efficient substitution reactions with various nucleophiles.
- Fujioka, Hiromichi,Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Yahata, Kenzo,Sawama, Yoshinari,Maegawa, Tomohiro
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supporting information; experimental part
p. 3976 - 3978
(2010/08/13)
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- A mild titanium-based system for the reduction of amides to aldehydes
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A mild method for the reduction of amides to aldehydes using 1,1,3,3-tetramethyldisiloxane/titanium(IV) isopropoxide reducing system is described. The reaction occurs under mild conditions and allows the reduction of aromatic as well as aliphatic, tertiary amides to the corresponding aldehydes, in good yields. This methodology was extended to the reduction of aromatic secondary and primary amides to the corresponding aldehydes.
- Laval, Stéphane,Dayoub, Wissam,Favre-Reguillon, Alain,Demonchaux, Patrice,Mignani, Gérard,Lemaire, Marc
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scheme or table
p. 2092 - 2094
(2010/06/14)
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- PROCESS FOR PREPARING PURE CYCLODODECANONE
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The present invention relates to a process for preparing at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group, at least comprising the stages: (a1) oxidation of a composition (A), at least comprising one cyclic olefin with Z cycles and 7 to 16 carbon atoms and at least two C—C double bonds, by means of dinitrogen monoxide to give a composition (A1),(a2) separating off the at least one cyclic olefin with Z cycles and 7 to 16 carbon atoms with at least two C—C double bonds from the composition (A1) in order to obtain a composition (A2), and(b) distillative treatment of the composition (A2) from step (a2) in order to obtain a composition (B), comprising the at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group andless than 1.0% by weight of the at least one compound with Z?1 cycles and 7 to 16 carbon atoms with at least one aldehyde group, where Z can be 1, 2, 3 or 4.
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Page/Page column 18-19
(2010/08/07)
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- Synthesis and C-alkylation of hindered aldehyde enamines
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A new reactivity mode of hindered lithium amides with terminal epoxides is described whereby aldehyde enamines are produced via a previously unrecognized reaction pathway. Some of these aldehyde enamines display unprecedented C-alkylation reactivity toward unactivated primary and secondary alkyl halides. For comparison, the reactivity of aldehyde enamines synthesized via a traditional condensation method was examined. C-rather than N-alkylation was the dominant reaction pathway found with a range of electrophiles, making this route to α-alkylated aldehydes more synthetically useful than previously reported.
- Hodgson, David M.,Bray, Christopher D.,Kindon, Nicholas D.,Reynolds, Nigel J.,Coote, Steven J.,Um, Joann M.,Houk
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body text
p. 1019 - 1028
(2009/07/04)
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- Oxidoperoxidotungsten(VI) complexes with secondary hydroxamic acids: Synthesis, structure and catalytic uses in highly efficient, selective and ecologically benign oxidation of olefins, alcohols, sulfides and amines with H2O2 as a terminal oxidant
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The reaction of a solution of freshly precipitated WO3 in H 2O2 separately with the secondary hydroxamic acids N-benzoyl-N-phenylhydroxamic acid (BPHAH), N-benzoyl-Northo-tolylhydroxamic acid (BOTHAH), N-benzoyl-N-meta-tolylhydroxamic acid (BMTHAH), N-benzoyl-N-para- tolyl-hydroxamic acid (BPTHAH) and N-cinnamyl-N-phenylhy-droxamic acid (CPHAH) afforded [WO(O2)(BPHA)2] (1), [WO(O2)(BOTHA) 2] (2), [WO(O2)(BMTHA)2] (3), [WO(O 2)-(BPTHA)2] (4) and [WO(O2)(CPHA)2] (5), respectively. Aqueous tungstate solution, on reaction with all these hydroxamic acids, produced [W(O)2(hydroxamato)2] (6). The complexes show excellent catalytic functions in the oxidation of (a) olefins at room temperature in the presence of NaHCO3 as promoter, (b) alcohols, sulfides and amines, at reflux, with H2O2 as a terminal oxidant, yielding a high turnover number (TON), the highest being for olefin-to-epoxide conversion. An attempt to synthesize peroxide-rich complexes of the type PPh4[WO(O2)2(hydroxamato)] (7), for example PPh4[WO-(O2)2BMTHA] (7C), resulted in the isolation of PPh4[WO-(O2)2(C 6H5COO)] (8), which was probably obtained by the hydrolysis of coordinated BMTHA. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Maiti, Swarup K.,Dinda, Subhajit,Banerjee, Surajit,Mukherjee, Alok K.,Bhattacharyya, Ramgopal
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experimental part
p. 2038 - 2051
(2009/03/11)
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- Environmentally friendly organic synthesis using bismuth compounds: bismuth(III) iodide catalyzed deprotection of acetals in water
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The chemoselective deprotection of a wide range of acetals and ketals in water is catalyzed by bismuth(III) iodide. Bismuth(III) compounds are remarkably nontoxic and hence are attractive as environmentally friendly catalysts.
- Bailey, Aaron D.,Baru, Ashvin R.,Tasche, Kendall K.,Mohan, Ram S.
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p. 691 - 694
(2008/09/17)
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- Photosensitized electron transfer oxidation of sulfides: A steady-state study
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The photosensitized electron-transfer oxidation of a series of ethyl sulfides RSEt (1, R = C12H25; 2, PhCH2CH 2; 3, PhCH2; 4, PhCMe2; 5, Ph2CH) has been examined in acetonitrile and the product distribution discussed on the basis of the mechanisms proposed. In nitrogen-flushed solutions, cleaved alcohols and alkenes are formed, whereas under oxygen, in reactions that are 10-70 times faster, sulfoxides and cleaved aldehydes and ketones are formed in addition to the afore-mentioned products. Two sensitizers are compared, 9,10-dicyanoanthracene (DCA) and 2,4,6-triphenylpyrylium tetrafluoroborate (TPP+BF4-), the former giving a higher proportion of the sulfoxide, the latter of cleaved carbonyls. The sulfoxidation is due to the contribution of the singlet oxygen path with DCA. Oxidative cleavage, on the other hand, occurs both with DCA and with TPP+ which is known to produce neither singlet oxygen nor the superoxide anion. This process involves deprotonation from the α position of the sulfide radical cation, but the TPP+ results suggest that O2.- is not necessarily involved and non-activated oxygen forms a weak adduct with the radical cation promoting α-hydrogen transfer, particularly with benzylic derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Bonesi, Sergio M.,Fagnoni, Maurizio,Albini, Angelo
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scheme or table
p. 2612 - 2620
(2009/04/05)
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- Mesityltriphenylbismuthonium tetrafluoroborate as an efficient bismuth(V) oxidant: remarkable steric effects on reaction rates and chemoselectivities in alcohol oxidation
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In the presence of N,N,N′,N′-tetramethylguanidine, mesityltriphenylbismuthonium tetrafluoroborate oxidizes primary and secondary alcohols to aldehydes and ketones, respectively, under mild conditions. In this reaction, the mesityl ligand exclusively abstracts an α-hydrogen to afford mesitylene and triphenylbismuthane as side products. A remarkable steric effect has also been exhibited in the chemoselective oxidation between primary and secondary alcohols.
- Matano, Yoshihiro,Suzuki, Takeshi,Shinokura, Tomonori,Imahori, Hiroshi
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p. 2885 - 2888
(2008/02/03)
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- Deprotection of thioacetals using K2S2O 8/[bmim]Br as a mild and efficient reagent under solvent-free conditions
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A straightforward and effective procedure for the deprotection of thioacetals to the corresponding carbonyl compounds using potassium persulfate and the ionic liquid [bmim]Br under solvent-free conditions is reported. A variety of aliphatic and aromatic 1,3-dithiolanes or 1,3-dithanes was deprotected to the corresponding carbonyl derivatives by this procedure. Springer-Verlag 2007.
- Hajipour, Abdol R.,Mostafavi, Majid,Ruoho, Arnold E.
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p. 569 - 572
(2008/02/03)
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- An efficient conversion of carboxylic acids to one-carbon degraded aldehydes via 2-hydroperoxy acids
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After the formation of dianions of a carboxylic acid with lithium diisopropylamide, oxygen was bubbled into the solution to produce 2-hydroperoxy acid. Then the reaction mixture was acidified with a 2N HCl solution and subsequently elevated to 50°C to afford the aldehyde with the loss of one carbon atom. Even saturated (C10-C20) and unsaturated (C18:1) carboxylic acids were converted into the odd aldehydes (C9-C19, C17:1) in high yields. This conversion was found to be an efficient method for the preparation of carboxylic acids (Cn) to one-carbon degraded aldehydes (Cn-1) via 2-hydroperoxy acids.
- Akakabe, Yoshihiko,Nyuugaku, Takeshi
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p. 1370 - 1371
(2008/02/07)
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