- Highly Selective Silica-supported Copper Catalysts Derived from Copper Phyllosilicates in the Hydrogenation of Adipic Acid to 1,6-hexanediol
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Hydrogenation of adipic acid (AA) is a potential way to prepare 1,6-hexanediol (HDOL). Herein, silica-supported copper catalysts derived from copper phyllosilicates were synthesized, characterized, and tested in the hydrogenation of AA to HDOL. In a full conversion of AA, a high yield of HDOL (approximately 90 %) was obtained through the use of each Cu-based catalyst. The turnover frequency calculated according to the consumption rate of AA was discovered to be dependent on the Cu+/(Cu0+Cu+) ratio and the reduction condition. Moreover, recycling tests showed that a catalyst derived from a copper phyllosilicate had better stability compared with Cu/SiO2 made through impregnation due to a stronger interaction between Cu and silica. The kinetic analyses based on the global rate expression and Langmuir?Hinshelwood?Hougen?Watson (LHHW) formalism of AA conversion were conducted. The possible competitive adsorption between AA and its derivatives, including hydroxycaproic acid and ?-caprolactone, was thereby revealed.
- Jiang, Jia-Wei,Tu, Cheng-Chieh,Chen, Chao-Huang,Lin, Yu-Chuan
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- Alkoxy-1,3,5-triazapentadien(e/ato) copper(II) complexes: Template formation and applications for the preparation of pyrimidines and as catalysts for oxidation of alcohols to carbonyl products
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Template combination of copper acetate (Cu(AcO)2·H 2O) with sodium dicyanamide (NaN(C≡N)2, 2 equiv) or cyanoguanidine (N≡CNHC(=NH)NH2, 2 equiv) and an alcohol ROH (used also as solvent) leads to the neutral copper(II)-(2,4-alkoxy-1,3,5- triazapentadienato) complexes [Cu{NH=C(OR)NC(OR)=NH}2] (R=Me (1), Et (2), nPr (3), iPr (4), CH2CH2OCH3 (5)) or cationic copper(II)-(2-alkoxy-4-amino-1,3,5-triazapentadiene) complexes [Cu{NH=C(OR)NHC(NH2)=NH}2](AcO)2 (R=Me (6), Et (7), nPr (8), nBu (9), CH2CH2OCH3 (10)), respectively. Several intermediates of this reaction were isolated and a pathway was proposed. The deprotonation of 6-10 with NaOH allows their transformation to the corresponding neutral triazapentadienates [Cu{NH=C(OR)NC(NH 2)=NH}2] 11-15. Reaction of 11, 12 or 15 with acetyl acetone (MeC(=O)CH2C(=O)Me) leads to liberation of the corresponding pyrimidines NC(Me)CHC(Me)NCNHC(=NH)OR, whereas the same treatment of the cationic complexes 6, 7 or 10 allows the corresponding metal-free triazapentadiene salts {NH2C(OR)=NC(NH2)=NH 2}(OAc) to be isolated. The alkoxy-1,3,5-triazapentadiene/ato copper(II) complexes have been applied as efficient catalysts for the TEMPO radical-mediated mild aerobic oxidation of alcohols to the corresponding aldehydes (molar yields of aldehydes of up to 100% with >99% selectivity) and for the solvent-free microwave-assisted synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant (yields of up to 97%, turnover numbers of up to 485 and turnover frequencies of up to 1170 h-1). One pot for the lot: Alkoxy-1,3,5-triazapentadien(e/ato)-CuII complexes have been synthesised by one-pot template synthesis, used for metal-mediated synthesis of pyrimidines and triazapentadienes, and shown to be effective catalysts in the oxidation of alcohols to carbonyl products (see scheme). Copyright
- Kopylovich, Maximilian N.,Karabach, Yauhen Yu.,Guedes Da Silva, M. Fatima C.,Figiel, Pawel J.,Lasri, Jamal,Pombeiro, Armando J. L.
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- Solvent-free microwave-assisted peroxidative oxidation of secondary alcohols to the corresponding ketones catalyzed by copper(ii) 2,4-alkoxy-1,3,5-triazapentadienato complexes
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A facile, efficient and selective solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide (TBHP) as the oxidant under microwave irradiation is achieved, where the copper(ii) 2,4-alkoxy-1,3,5- triazapentadienato complexes are efficient catalysts providing high yields (up to 100%), TONs (up to 890) and TOFs (up to 1780 h-1).
- Figiel, Pawel J.,Kopylovich, Maximilian N.,Lasri, Jamal,Da Silva, M. Fatima C. Guedes,Da Silva, Joao J. R. Frausto,Pombeiro, Armando J. L.
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- MULTIFUNCTIONAL MICELLAR CATALYSIS AS A MODEL OF ENZYME ACTION.
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The rate constants of both the acylation and deacylation processes in the hydrolyses of p-nitrophenyl acetate (PNPA) and hexanoate (PNPH) by imidazole catalysts (1) in the presence of surfactant micelles (2) have been directly determined under single turnover conditions at pH 7. 30 in 0. 02 M phosphate buffer and 25 degree C. The major course of catalysts was the acylation followed by deacylation at the imidazole group. The kinetic analysis suggests that a multifunctional mode of action is involved in the catalystic ester hydrolysis; the acylation and deacylation rates are accelerated by carboxylate ion in the catalyst and by surfactant hydroxyl group, respectively.
- Ihara,Nango,Kimura,Kuroki
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- Aroma compounds formed from 3-methyl-2,4-nonanedione under photooxidative conditions
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The behavior of the prominent aroma compound 3-methyl-2,4-nonanedione under photooxidative conditions was investigated in a model experiment. The four well-known aroma compounds 2,3-butanedione, 2,3-octanedione, acetic acid, and caproic acid were identified. The main oxidation product was 3-hydroxy-3-methyl-2,4-nonanedione, an aroma compound with the odor description of rubbery, earthy, and plasticlike (GC-O). Its structure has been tentatively assigned based on mass (GC-MS) and vapor phase infrared spectra (GC-IR). The formal formation pathways are discussed for these compounds, and other origins described in the literature are presented.
- Sigrist, Isabelle A.,Manzardo, Giuseppe G. G.,Amado, Renato
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- Two-fold interpenetrating btc based cobaltous coordination polymer: A promising catalyst for solvent free oxidation of 1-hexene
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This work describes the synthesis of a new 2-D coordination polymer (CP), [Co3(btc)2(dmp)8]n (btc = 1,3,5-benzenetricarboxylate and dmp = 3,5-dimethylpyrazole) and its catalytic activity towards the oxidation reaction of 1-hexene to form oxygenated compounds under solvent free condition. Structural analysis reveals that Co(II) cations in this polymeric compound are linked by btc3- anions with alternate tetrahedral/octahedral coordination forming a two-fold interpenetrated 3-connected hcb underlying net. Electronic spectrum of the cobaltous polymer has been calculated using TDDFT/B3LYP method for making the appropriate assignments of electronic transitions. Catalytic results show good conversions of the starting material to oxygenated products with high selectivities for 1,2-epoxyhexane and 1-hexanal.
- Bora, Sanchay J.,Paul, Rima,Nandi, Mithun,Bhattacharyya, Pradip K.
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- Organic solvent nanofiltration and adsorbents; A hybrid approach to achieve ultra low palladium contamination of post coupling reaction products
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Due to potentially toxic contamination of pharmaceutical products, effective removal of palladium from post-reaction solutions is of great importance, especially in the pharmaceutical industry. This work addresses this challenge by combining organic solvent nanofiltration (OSN) with adsorbents in a hybrid process. Post-reaction solutions resulting from acylation and Suzuki reactions were subjected to OSN, the catalyst was retained by the membrane, and the product was collected in the permeate. Palladium levels in the permeate were reduced further by using adsorbents. This technique achieved ultralow palladium concentration (-1 for post-reaction solutions with toluene and ethyl acetate as solvents. The results obtained using the hybrid OSN-adsorbent process were compared to those using selected adsorbents only. When palladium was removed from a post-Suzuki reaction solution, using polystyrenebound trimercaptotriazine as the adsorbent, the hybrid process, while using 10 times less adsorbent than the adsorbent-only process, was able to reduce the product contamination to an 8.5 times lower level. It is thought that the membrane stage of this technique removes bulky ligated palladium along with palladium nanoparticles, species that are hard to remove by adsorption only. The residual palladium in the permeate stream comprises well-dissolved, smaller molecules, and these are removed very effectively by the adsorbent. This allows high-purity products to be achieved by treatment of the OSN permeate with low amounts of absorbents. Therefore, this hybrid process is recommended for separations where adsorbent-only treatment can result in significant product losses, or where strong ligand-palladium interactions compete with adsorbent active sites, keeping palladium in solution.
- Pink, Christopher J.,Wong, Hau-To,Ferreira, Frederico C.,Livingston, Andrew G.
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- Antioxidative activity of heterocyclic compounds found in coffee volatiles produced by Maillard reaction
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Typical heterocyclic compounds substituted with various functional groups found in Maillard reaction products were examined for antioxidant activity. Pyrroles exhibited the greatest antioxidant activity among all heterocyclic compounds tested. All pyrroles inhibited hexanal oxidation by almost 100% at a concentration of 50 μg/mL over 40 days. Addition of formyl and acetyl groups to a pyrrole ring enhanced antioxidative activity remarkably. Pyrrole-2-carboxaldehyde, 2-acetylpyrrole, 1-methyl-2-pyrrolecarboxaldehyde, and 2-acetyl-1-methylpyrrole inhibited hexanal oxidation by >80% at 10 μg/mL. Unsubstituted furan exhibited the greatest antioxidant activity among furans tested. Addition of all functional groups used in this study to furan decreased antioxidative activity. The antioxidant activity of thiophene increased with the addition of methyl and ethyl groups, but the addition of formyl or acetyl groups to thiophene decreased antioxidant activity. Thiazoles and pyrazines were ineffective antioxidants at all concentrations tested. Reaction of all heterocyclic compounds with hydrogen peroxide resulted in the formation of various oxidized products.
- Yanagimoto, Kenichi,Lee, Kwang-Geun,Ochi, Hirotomo,Shibamoto, Takayuki
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- A Direct Conversion of (α-Hydroxyalkyl)silanes to Carboxylic Acids
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(α-Hydroxyalkyl)trialkylsilanes and acylsilanes are readily oxidized to the corresponding carboxylic acid using ozone.
- Linderman, Russell J.,Chen, Kangyi
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- Biotransformation of linoleic acid into hydroxy fatty acids and carboxylic acids using a linoleate double bond hydratase as key enzyme
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Hydroxy fatty acids are used as starting materials for the production of secondary metabolites and signalling molecules as well as in the manufacture of industrial fine chemicals. However, these compounds are usually difficult to produce from renewable biomass by chemical means. In this study, linoleate double bond hydratases of Lactobacillus acidophilus NBRC 13951 were cloned for the first time. These enzymes were highly specific for the hydration of the C-9 or the C-12 double bond of unsaturated fatty acids (e.g., linoleic acid). Thereby, the enzymes allowed the selective production of hydroxy fatty acids such as 13-hydroxy- cis -9-octadecenoic acid and 10-hydroxy- cis -12-octadecenoic acid from linoleic acid. In addition, the hydroxy fatty acids were further converted into industrially relevant carboxylic acids (e.g., 12-hydroxy-cis-9-dodecenoic acid, a, w-tridec-9-enedioic acid) and lactones (i.e., d-decalactone, g-dodecelactone) via whole-cell biocatalysis using an enzyme cascade. This study thus contributes to the preparation of hydroxy fatty acids, unsaturated carboxylic acids, and lactones from renewable unsaturated fatty acids.
- Oh, Hye-Jin,Kim, Sae-Um,Song, Ji-Won,Lee, Jung-Hoo,Kang, Woo-Ri,Jo, Ye-Seul,Kim, Kyoung-Rok,Bornscheuer, Uwe T.,Oh, Deok-Kun,Park, Jin-Byung
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- Enantioselective oxidation of aldehydes catalyzed by alcohol dehydrogenase
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Teaching old dogs new tricks: Alcohol dehydrogenases (ADHs) may be established redox biocatalysts but they still are good for a few surprises. ADHs can be used to oxidize aldehydes, and this was demonstrated by the oxidative dynamic kinetic resolution of profens. In the presence of a suitable cofactor regeneration system, this reaction can occur with high selectivity. Copyright
- K?nst, Paul,Merkens, Hedda,Kara, Selin,Kochius, Svenja,Vogel, Andreas,Zuhse, Ralf,Holtmann, Dirk,Arends, Isabel W. C. E.,Hollmann, Frank
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- Reduction of olefins on solid support using diimide
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The reduction of solid supported olefinic substrate using diimide is described. The diimide, prepared from sulfonylhydrazide, was found to efficiently reduce the olefinic substrates. Typically, the reaction proceeds in over 90% yield to afford the reduction product cleanly after cleavage from the Wang resin.
- Lacombe, Patrick,Castagner, Bastien,Gareau, Yves,Ruel, Rejean
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- Electro-oxidative Neutral Deprotection of S-t-Butyl Thioates to give Carboxylic Acids
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t-Butyl thioates are proposed as a convenient protecting group for carboxylic acids, because their deprotection under neutral conditions can be attained by electro-oxidation using bromide salts as electrolytes in aqueous acetonitrile.
- Kimura, Makoto,Matsubara, Shinichi,Sawaki, Yasuhiko
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- Oxidation of aldehydes on TiO2 photocatalysts modified with alkylsilyl group
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Surfaces of SiO2-covered TiO2 photocatalysts were modified with alkylsilyl groups. Oxidation of hexanal on surface-modified TiO2 proceeded more efficiently than that on photocatalysts without surface modification. The improvement of the photocatalytic activities of surface-modified TiO2 photocatalysts is due to the hydrophobic interaction between hexanal and alkylsilyl groups modified on TiO2 photocatalysts. Copyright
- Ohno, Teruhisa,Tsubota, Toshiki,Kakiuchi, Kosuke,Sayama, Kazuhiro
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- Gram-scale synthesis of carboxylic acids via catalytic acceptorless dehydrogenative coupling of alcohols and hydroxides at an ultralow Ru loading
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Acceptorless dehydrogenative coupling (ADC) of alcohols and water/hydroxides is an emergent and graceful approach to produce carboxylic acids. Therefore, it is of high demand to develop active and practical catalysts/catalytic systems for this attractive transformation. Herein, we designed and fabricated a series of cyclometallated N-heterocyclic carbene-Ru (NHC-Ru) complexes via ligand tuning of [Ru-1], the superior complex in our previous work. Gratifyingly, gram-scale synthesis of carboxylic acids was efficiently enabled at an ultralow Ru loading (62.5 ppm) in open air. Moreover, effects of distinct ancillary NHC ligands and other parameters on this catalytic process were thoroughly studied, while further systematic studies were carried out to provide rationales for the activity trend of [Ru-1]-[Ru-7]. Finally, determination of quantitative green metrics illustrated that the present work exhibited superiority over representative literature reports. Hopefully, this study could provide valuable input for researchers who are engaging in metal-catalyzed ADC reactions.
- Chen, Cheng,Cheng, Hua,Verpoort, Francis,Wang, Zhi-Qin,Wu, Zhe,Yuan, Ye,Zheng, Zhong-Hui
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- STRONGLY LEWIS ACIDIC METAL-ORGANIC FRAMEWORKS FOR CONTINUOUS FLOW CATALYSIS
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Lewis acidic metal-organic framework (MOF) materials comprising triflate-coordinated metal nodes are described. The materials can be used as heterogenous catalysts in a wide range of organic group transformations, including Diels-Alder reactions, epoxide-ring opening reactions, Friedel-Crafts acylation reactions and alkene hydroalkoxylation reactions. The MOFs can also be prepared with metallated organic bridging ligands to provide heterogenous catalysts for tandem reactions and/or prepared as composites with support particles for use in columns of continuous flow reactor systems. Methods of preparing and using the MOF materials and their composites are also described.
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- Aqueous Persistent Noncovalent Ion-Pair Cooperative Coupling in a Ruthenium Cobaltabis(dicarbollide) System as a Highly Efficient Photoredox Oxidation Catalyst
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An original cooperative photoredox catalytic system, [RuII(trpy)(bpy)(H2O)][3,3′-Co(1,2-C2B9H11)2]2 (C4; trpy = terpyridine and bpy = bipyridine), has been synthesized. In this system, the photoredox metallacarborane catalyst [3,3′-Co(1,2-C2B9H11)2]- ([1]-) and the oxidation catalyst [RuII(trpy)(bpy)(H2O)]2+ (C2′) are linked by noncovalent interactions and not through covalent bonds. The noncovalent interactions to a large degree persist even after water dissolution. This represents a step ahead in cooperativity avoiding costly covalent bonding. Recrystallization of C4 in acetonitrile leads to the substitution of water by the acetonitrile ligand and the formation of complex [RuII(trpy)(bpy)(CH3CN)][3,3′-Co(1,2-C2B9H11)2]2 (C5), structurally characterized. A significant electronic coupling between C2′ and [1]- was first sensed in electrochemical studies in water. The CoIV/III redox couple in water differed by 170 mV when [1]- had Na+ as a cation versus when the ruthenium complex was the cation. This cooperative system leads to an efficient catalyst for the photooxidation of alcohols in water, through a proton-coupled electron-transfer process. We have highlighted the capacity of C4 to perform as an excellent cooperative photoredox catalyst in the photooxidation of alcohols in water at room temperature under UV irradiation, using 0.005 mol % catalyst. A high turnover number (TON = 20000) has been observed. The hybrid system C4 displays a better catalytic performance than the separated mixtures of C2′ and Na[1], with the same concentrations and ratios of Ru/Co, proving the history relevance of the photocatalyst. Cooperative systems with this type of interaction have not been described and represent a step forward in getting cooperativity avoiding costly covalent bonding. A possible mechanism has been proposed.
- Guerrero, Isabel,Vi?as, Clara,Fontrodona, Xavier,Romero, Isabel,Teixidor, Francesc
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p. 8898 - 8907
(2021/06/28)
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- An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle
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The coordination chemistry of the anionic NHC1-based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d6(Ru(II), Mn(I)) and d8(Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1·H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1-through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)]?with PhICl2as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The νCOstretching frequencies recorded for complex [Rh(1)(CO)2] (5) demonstrated the strong donating character of the malonate-C(sp3)/NHC ligand 1-. The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25-250 ppm) and a large tolerance toward functional groups.
- Benaissa, Idir,Gajda, Katarzyna,Vendier, Laure,Lugan, No?l,Kajetanowicz, Anna,Grela, Karol,Michelet, Véronique,César, Vincent,Bastin, Stéphanie
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p. 3223 - 3234
(2021/09/30)
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- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
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supporting information
p. 14701 - 14706
(2021/05/13)
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- Catalytic hydrogenation of sorbic acid using pyrazolyl palladium(II) and nickel(II) complexes as precatalysts
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We have prepared several pyrazolyl palladium and nickel complexes ([(L1)PdCl2] (1), [(L2) PdCl2] (2), [(L3) PdCl2] (3), [(L1) NiBr2] (4), [(L2) NiBr2] (5) and [(L3) NiBr2] (6)) by reacting 3,5-dimethyl-1H-pyrazole (L1), 3,5-di-tert-butyl-1H-pyrazole (L2) and 5-ferrocenyl-1H-pyrazole(L3) with [PdCl2(NCMe)2] or [NiBr2(DME)] to afford mononuclear palladium and nickel complexes, respectively. These complexes were then investigated as pre-catalysts in the hydrogenation of 2,4-hexadienoic acid (sorbic acid). The active catalysts from these complexes demonstrate significant activities under mild experimental conditions. Additionally, the active catalysts show that the hydrogenation of sorbic acid proceeds in a sequential manner, where the less hindered C=C bond (4-hexenoic acid) is preferentially reduced over the more hindered C=C bond (2-hexenoic acid).
- Darkwa, James,Kumar, Gopendra,Makhubela, Banothile C. E.,Muyaneza, Apollinaire,Olaoye, Oluwasegun E.,Oyetunji, Olayinka
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- Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
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Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
- Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
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- Green, homogeneous oxidation of alcohols by dimeric copper(II) complexes
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Three pyrazole derivatives, 3,5-dimethyl-1H-pyrazole (DMPz) (I), 3-methyl-5-phenyl-1H-pyrazole (MPPz) (II), and 3,5-diphenyl-1H-pyrazole (DPPz) (III), were prepared via reacting semicarbazide hydrochloride with the acetylacetone, 1-phenylbutane-1,3-dione, and 1,3-diphenylpropane-1,3-dione, respectively. Complexes 1–3 were isolated by reacting CuCl2·2H2O with I–III, respectively, and characterized by CHNS elemental analyses, FT-IR, UV-Vis, 1H and 13C NMR, EPR spectra, and TGA/DTA. Molecular structures of the pyrazole derivatives I–III and copper(II) complexes 2 and 3 were studied through single-crystal XRD analysis to confirm their molecular structures. Overlapping of hyperfine splitting in the EPR spectra of the dimeric copper(II) complexes 1–3 indicates that both copper centers do not possess the same electronic environment in solution. The copper(II) complexes are dimeric in solid state as well as in solution and catalyze the oxidation of various primary and secondary alcohols selectively. Catalysts 1–3 show more than 92% product selectivity toward ketones during the oxidation of secondary alcohols. Surprisingly primary alcohols, which are relatively difficult to oxidize, produce carboxylic acid as a major product (48%–90% selectivity) irrespective of catalytic systems. The selectivity for carboxylic acid rises with decreasing the carbon chain length of the alcohols. An eco-friendly and affordable catalytic system for oxidation of alcohols is developed by the utilization of H2O2, a green oxidant, and water, a clean and greener solvent, which is a notable aspect of the study.
- Maurya, Abhishek,Haldar, Chanchal
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p. 885 - 904
(2020/12/18)
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- Synthesis of TEMPO radical decorated hollow porous aromatic frameworks for selective oxidation of alcohols
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A bottom-up approach was developed to prepare TEMPO radical decorated hollow aromatic frameworks (HPAF-TEMPO) by using TEMPO radical functionalized monomers and SiO2nanospheres as templates. The accessible inner layer, high density of TEMPO sites, and hybrid micro-/mesopores of the HPAF-TEMPO enable the aerobic oxidation of a broad range of alcohols with high efficiency and excellent selectivity.
- Shen, Yan-Ming,Xue, Yun,Yan, Mi,Mao, Hui-Ling,Cheng, Hu,Chen, Zhuo,Sui, Zhi-Wei,Zhu, Shao-Bin,Yu, Xiu-Jun,Zhuang, Jin-Liang
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supporting information
p. 907 - 910
(2021/02/06)
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- Aerobic oxidation of aldehydes to acids with N-hydroxyphthalimide derivatives
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The N-hydroxyphthalimide derivative-mediated aerobic oxidation of a selection of aldehydes to the corresponding carboxylic acids in air is described. This reaction proceeds via rearrangement of the Creigee (carboxylic peracid) intermediate and/or by the treatment of H2O and/or sulfides. Optimization of reaction conditions established NHNPI (14) as a mild catalyst for the oxidation reaction in MeCN under an atmosphere of air.
- Takamatsu, Keigo,Kasai, Miku,Nishizawa, Hinaru,Suzuki, Rio,Konno, Hiroyuki
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Ruthenium-catalysed hydroxycarbonylation of olefins
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State-of-the-art catalyst systems for hydroxy- and alkoxycarbonylations of olefins make use of palladium complexes. In this work, we report a complementary ruthenium-catalysed hydroxycarbonylation of olefins applying an inexpensive Ru-precursor (Ru3(CO)12) and PCy3as a ligand. Crucial for the success of this transformation is the use of hexafluoroisopropanol (HFIP) as the solvent in the presence of an acid co-catalyst (PTSA). Overall, moderate to good yields are obtained using aliphatic olefins including the industrially relevant substrate di-isobutene. This atom-efficient catalytic transformation provides straightforward access to various carboxylic acids from unfunctionalized olefins.
- Dühren, Ricarda,Kucmierczyk, Peter,Jackstell, Ralf,Franke, Robert,Beller, Matthias
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p. 2026 - 2030
(2021/04/09)
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- Membrane transport inspired hydrolysis of non-activated esters at near physiological pH
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A positively charged micelle loaded with substrates was transported selectively to the reaction site (cathode) to promote the proximity and localization of the reactants (ester and hydroxide). The guided vehicular delivery coupled with electrolysis allows the hydrolysis of non-activated esters at near physiological pH with significant yields along with recyclability.
- Mandal, Raki,Mahanty, Kingshuk,Mandal, Subhendu,De Sarkar, Suman,Tarafdar, Pradip K.
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p. 11088 - 11091
(2021/10/30)
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- BiCl3-Facilitated removal of methoxymethyl-ether/ester derivatives and DFT study of -O-C-O- bond cleavage
-
A simple method for the cleavage of methoxymethyl (MOM)-ether and ester derivatives using bismuth trichloride (BiCl3) is described. The alkyl, alkenyl, alkynyl, benzyl and anthracene MOM ether derivatives, as well as MOM esters of both aliphatic and aromatic carboxylic acids, were deprotected in good yields. To better understand the molecular roles of BiCl3and water for MOM cleavage, two possible binding pathways were investigated using the density functional theory (DFT) method. The theoretical results indicate the differential initial binding site preferences of phenolic and alcoholic MOM substrates to the Bi atom and suggest that water plays a key role in facilitating the cleavage of the MOM group.
- Pacherille, Angela,Tuga, Beza,Hallooman, Dhanashree,Dos Reis, Isaac,Vermette, Mélodie,Issack, Bilkiss B.,Rhyman, Lydia,Ramasami, Ponnadurai,Sunasee, Rajesh
-
supporting information
p. 7109 - 7116
(2021/05/03)
-
- In vitro studies of maleidride-forming enzymes
-
In vitro assays of enzymes involved in the biosynthesis of maleidrides from polyketides in fungi were performed. The results show that the enzymes are closely related to primary metabolism enzymes of the citric acid cycle in terms of stereochemical preferences, but with an expanded substrate selectivity. A key citrate synthase can react both saturated and unsaturated acyl CoA substrates to give solely anti substituted citrates. This undergoes anti-dehydration to afford an unsaturated precursor which is cyclised in vitro by ketosteroid-isomerase-like enzymes to give byssochlamic acid. This journal is
- Yin, Sen,Friedrich, Steffen,Hrupins, Vjaceslavs,Cox, Russell J.
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p. 14922 - 14931
(2021/05/19)
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- Substrate hydrophobicity and enzyme modifiers play a major role in the activity of lipase from: Thermomyces lanuginosus
-
Lipase from Thermomyces lanuginosus (TL) displays high affinity for long-chain substrates, such as triolein and other long-chain triacylglycerols. Aiming to broaden the substrate chain-length specificity, different aldehydes (naphthaldehyde, butyraldehyde, hexyl aldehyde and dodecyl aldehyde) and naphthyl isothiocyanate were grafted onto lipase TL through lysine coupling. The catalytic activity of the modified lipases was investigated by reaction with substrates differing in the aliphatic chain size (p-nitrophenyl benzoate, p-nitrophenyl acetate, p-nitrophenyl butyrate, p-nitrophenyl hexanoate, p-nitrophenyl octanoate, p-nitrophenyl laurate and p-nitrophenyl palmitate). The enzymes modified with aldehydes revealed higher activity than the enzymes modified with the isothiocyanate. The most notable results were achieved for lipase TL grafted with 4 units of a dodecyl chain (TL5), which revealed the highest activity against all the tested substrates, being 10-fold more active than the native enzyme for smaller substrates (acetate and butyrate chains) and 2-fold for longer substrates (laurate and palmitate chains). The kinetic parameters evaluated (Vmax, KM and kcat/KM) also confirmed the significant catalytic performance of TL5 compared to the native enzyme. The increase in activity revealed by the modified lipases was directly proportional to the size and hydrophobicity of the linkers' aliphatic chain. Small conformational changes, either on the enzyme's lid or on the cavity of the active site were suggested by molecular dynamics simulations, circular dichroism and fluorescence spectroscopy. Moreover, the grafting with aldehydes or with the isothiocyanate conferred higher thermostability to the lipase. The chemical surface modification developed efficiently improved the activity of lipase TL, broadening the substrate's chain-length specificity, increasing thereafter the substrate possibilities for industrial reactions. This journal is
- Castro, Tarsila G.,Cavaco-Paulo, Artur,Noro, Jennifer,Silva, Carla
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p. 5913 - 5924
(2020/10/08)
-
- Method for hydrogenolysis of halides
-
The invention discloses a method for hydrogenolysis of halides. The invention discloses a preparation method of a compound represented by a formula I. The preparation method comprises the following step: in a polar aprotic solvent, zinc, H2O and a compound represented by a formula II are subjected to a reaction as shown in the specification, wherein X is halogen; Y is -CHRR or R; hydrogenin H2O exists in the form of natural abundance or non-natural abundance. According to the preparation method, halide hydrogenolysis can be simply, conveniently and efficiently achieved through a simple and mild reaction system, and good functional group compatibility and substrate universality are achieved.
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Paragraph 0232; 0275-0277
(2021/01/11)
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- Metallacarboranes as Photoredox Catalysts in Water
-
Metallacarboranes with the shape of the Greek letter θ, such as [Co(C2B9H11)2]?, were tested, for the first time, as efficient photoredox catalysts in the oxidation of aromatic and aliphatic alcohols in water. Their efficiency is linked to their high solubility in water, their high oxidizing power (Co4+/3+), and their absence of fluorescence on excitation, among others. In most of the studied examples, using a catalyst load of 0.4 mol % gave high yields of 90–95 % with selectivity greater than 99 %. By reducing the catalyst load to 0.01 mol %, quantitative conversion of reactants to products was achieved, in some cases with greater than 99 % yield, high catalyst efficiency reaching a turnover number of 10 000, and a higher yield with a 45 times lower concentration of catalyst. The metallacarboranes can be recovered easily by precipitation on addition of [NMe4]Cl. A pathway for the photoredox-catalyzed oxidation of alcohols is proposed.
- Guerrero, Isabel,Kelemen, Zsolt,Romero, Isabel,Teixidor, Francesc,Vi?as, Clara
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p. 5027 - 5036
(2020/04/22)
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- Cobalt-Catalyzed Acceptorless Dehydrogenation of Alcohols to Carboxylate Salts and Hydrogen
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The facile oxidation of alcohols to carboxylate salts and H2 is achieved using a simple and readily accessible cobalt pincer catalyst (NNNHtBuCoBr2). The reaction follows an acceptorless dehydrogenation pathway and displays good functional group tolerance. The amine-amide metal-ligand cooperation in cobalt catalyst is suggested to facilitate this transformation. The mechanistic studies indicate that in-situ-formed aldehydes react with a base through a Cannizzaro-type pathway, resulting in potassium hemiacetolate, which further undergoes catalytic dehydrogenation to provide the carboxylate salts and H2
- Gunanathan, Chidambaram,Kishore, Jugal,Pattanaik, Sandip,Pradhan, Deepak Ranjan
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supporting information
(2020/03/03)
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- Production of Hydroxy Acids: Selective Double Oxidation of Diols by Flavoprotein Alcohol Oxidase
-
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
-
supporting information
p. 4869 - 4872
(2020/02/11)
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- Method for preparing carboxylic acid by green catalytic oxidation of aliphatic primary alcohol
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The invention relates to a method for preparing carboxylic acid by green catalytic oxidation of aliphatic primary alcohol. The method comprises the following steps of: adding aliphatic primary alcoholinto a reaction solvent, adding an N-hydroxyphthalimide-copper oxide catalyst, introducing oxygen during reaction, and carrying out reaction at 50-80DEG C under normal pressure for 6-24h to obtain carboxylic acid with high yield. Compared with the prior art, the method has the advantages that the oxidizing agent is green and environment-friendly, the catalyst is cheap and easy to prepare, easy toseparate from the product, convenient to recycle, the reaction conditions are mild and the like, therefore the method is a green oxidation method of aliphatic primary alcohol.
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Paragraph 0043-0046
(2020/12/30)
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- Sequential Connection of Mutually Exclusive Catalytic Reactions by a Method Controlling the Presence of an MOF Catalyst: One-Pot Oxidation of Alcohols to Carboxylic Acids
-
A functionalized metal-organic framework (MOF) catalyst applied to the sequential one-pot oxidation of alcohols to carboxylic acids controls the presence of a heterogeneous catalyst. The conversion of alcohols to aldehydes was acquired through aerobic oxidation using a well-known amino-oxy radical-functionalized MOF. In the same flask, a simple filtration of the radical MOF with mild heating of the solution completely altered the reaction media, providing radical scavenger-free conditions suitable for the autoxidation of the aldehydes formed in the first step to carboxylic acids. The mutually exclusive radical-catalyzed aerobic oxidation (the first step with MOF) and radical-inhibited autoxidation (the second step without MOF) are sequentially achieved in a one-pot manner. Overall, we demonstrate a powerful and efficient method for the sequential oxidation of alcohols to carboxylic acids by employing a readily functionalizable heterogeneous MOF. In addition, our MOF in-and-out method can be utilized in an environmentally friendly way for the oxidation of alcohols to carboxylic acids of industrial and economic value with broad functional group tolerance, including 2,5-furandicarboxylic acid and 1,4-benzenedicarboxylic acid, with good yield and reusability. Furthermore, MOF-TEMPO, as an antioxidative stabilizer, prevents the undesired oxidation of aldehydes, and the perfect "recoverability"of such a reactive MOF requires a re-evaluation of the advantages of MOFs from heterogeneity in catalytic and related applications.
- Kim, Seongwoo,Lee, Ha-Eun,Suh, Jong-Min,Lim, Mi Hee,Kim, Min
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p. 17573 - 17582
(2020/12/22)
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- METHOD FOR PRODUCING CARBONYL COMPOUND
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PROBLEM TO BE SOLVED: To allow a method that oxidizes a first or second alcohol compound to obtain a carbonyl compound to be conducted with a higher yield than that of a method that uses sodium hypochlorite as an oxidizer. SOLUTION: A first or second alcohol compound is oxidized, in the presence of tetraalkylammonium hypochlorite and, preferably, in coexistence with a nitroxy radical catalyst and a metal halide cocatalyst, to produce a carbonyl compound composed of an aldehyde compound, a carboxylic acid compound, and a ketone compound. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPO&INPIT
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Paragraph 0066; 0068
(2021/02/04)
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- Preparation method of bimetallic catalyst oxidation aldehyde synthetic carboxylic acid (by machine translation)
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The method is, in a reaction solvent: under normal pressure oxygen condition, under the action of a bimetallic catalyst under the action of a bimetallic catalyst under the action of a bimetallic catalyst under the action of a bimetallic catalyst, at, DEG, under stirring . under a stirring condition with an aldehyde compound as a substrate 10-90 °C in a reaction solvent under, a stirring condition under the action of a bimetallic catalyst . The reaction solution is stirred, for. 1-12h, hours at; room temperature, under, the action, of a bimetallic 1:1 catalyst Cu(OAc) under the action of a bimetallic catalyst under the action of a bimetallic catalyst under the action of a double-metal catalyst. 2 · H2 O And Co(OAc)2 · 44H2 O As the bimetallic catalyst, can achieve the highest yield of the carboxylic acid product, in high yield, by adjusting the reaction temperature, solvent, catalyst amount, for different types of the raw material aldehyde 98%. (by machine translation)
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Paragraph 0048-0049
(2020/05/30)
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- Oxidation of aromatic and aliphatic aldehydes to carboxylic acids by Geotrichum candidum aldehyde dehydrogenase
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Oxidation reaction is one of the most important and indispensable organic reactions, so that green and sustainable catalysts for oxidation are necessary to be developed. Herein, biocatalytic oxidation of aldehydes was investigated, resulted in the synthesis of both aromatic and aliphatic carboxylic acids using a Geotrichum candidum aldehyde dehydrogenase (GcALDH). Moreover, selective oxidation of dialdehydes to aldehydic acids by GcALDH was also successful.
- Hoshino, Tomoyasu,Yamabe, Emi,Hawari, Muhammad Arisyi,Tamura, Mayumi,Kanamaru, Shuji,Yoshida, Keisuke,Koesoema, Afifa Ayu,Matsuda, Tomoko
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-
- The plant pathogen enzyme AldC is a long-chain aliphatic aldehyde dehydrogenase
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Aldehyde dehydrogenases are versatile enzymes that serve a range of biochemical functions. Although traditionally considered metabolic housekeeping enzymes because of their ability to detoxify reactive aldehydes, like those generated from lipid peroxidation damage, the contributions of these enzymes to other biological processes are widespread. For example, the plant pathogen Pseudomonas syringae strain PtoDC3000 uses an indole-3-acetaldehyde dehydrogenase to synthesize the phytohormone indole-3-acetic acid to elude host responses. Here we investigate the biochemical function of AldC from PtoDC3000. Analysis of the substrate profile of AldC suggests that this enzyme functions as a long-chain aliphatic aldehyde dehydrogenase. The 2.5 ? resolution X-ray crystal of the AldC C291A mutant in a dead-end complex with octanal and NAD1 reveals an apolar binding site primed for aliphatic aldehyde substrate recognition. Functional characterization of site-directed mutants targeting the substrate- and NAD(H)-binding sites identifies key residues in the active site for ligand interactions, including those in the “aromatic box” that define the aldehyde-binding site. Overall, this study provides molecular insight for understanding the evolution of the prokaryotic aldehyde dehydrogenase superfamily and their diversity of function.
- Lee, Soon Goo,Harline, Kate,Abar, Orchid,Akadri, Sakirat O.,Bastian, Alexander G.,Chen, Hui-Yuan S.,Duan, Michael,Focht, Caroline M.,Groziak, Amanda R.,Kao, Jesse,Kottapalli, Jagdeesh S.,Leong, Matthew C.,Lin, Joy J.,Liu, Regina,Luo, Joanna E.,Meyer, Christine M.,Mo, Albert F.,Pahng, Seong Ho,Penna, Vinay,Raciti, Chris D.,Srinath, Abhinav,Sudhakar, Shwetha,Tang, Joseph D.,Cox, Brian R.,Holland, Cynthia K.,Cascella, Barrie,Cruz, Wilhelm,McClerkin, Sheri A.,Kunkel, Barbara N.,Jez, Joseph M.
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p. 13914 - 13926
(2020/12/09)
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- 9,10-Dihydroanthracene auto-photooxidation efficiently triggered photo-catalytic oxidation of organic compounds by molecular oxygen under visible light
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The development of mild and efficient process for the selective oxidation of organic compounds by molecular oxygen (O2) can be one of the key technologies for synthesizing oxygenates. This paper discloses an efficient and mild synthesis protocol for the O2-involved ethylbenzene (EB) photooxidation triggered by 910-dihydroanthracene (DHA) auto- photooxidation in acetone under visible light illumination, which can achieve 87.7 percent EB conversion and 99.5 percent acetylacetone (ACP) selectivity under ambient conditions. Also, 62.9 percent EB conversion and 96.3 percent ACP selectivity is obtained in air atmosphere. Furthermore, this protocol has a good adaptability for the photooxidation of other organic substrates such as tetrahydronaphthalene, diphenylmethane, toluene, cyclohexane, cyclohexene, alcohol, methylfuran and thioether to their corresponding oxygenates. A series of control and quenching tests, combined with EPR spectra, suggest that the photo-excited DHA can transfer its photo-electron to O2 to yield a superoxide radical anion (O2??), then DHA is preferentially oxidized to anthraquinone (AQ) by the active O2?? owing to its high reactivity. Finally, the in situ generated AQ as an active photo-catalyst can achieve the photooxidation of EB and other organic compounds by O2. The present photo-autoxidation protocol gives a good example for the O2-based selective oxidation of inert hydrocarbons under mild conditions.
- Chen, Mengke,Deng, Youer,Fu, Zaihui,Hu, Wenwei,Jiang, Dabo,Liu, Yachun,Mao, Feng,Su, Anqun,Yang, Bo,Zhang, Chao
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-
- Transformations of N-arylpropiolamides to indoline-2,3-diones and acids via C≡C triple bond oxidative cleavage and C(sp2)–H functionalization
-
A new palladium-catalyzed oxidative conversion of N-arylpropiolamides and H2O to various indoline-2,3-diones and acids through the C≡C triple bond cleavage and C(sp2)–H functionalization is described, which is promoted by a cooperative action of catalytic CuBr2, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and O2. The method provides a practical tool for transformations of alkynes by means of a C–H functionalization strategy, which enables the formation of one C–C bond and multiple C–O bonds in a single reaction with high substrates compatibility and excellent functional group tolerance.
- Zhou, Ming-Bo,Li, Yang,Ouyang, Xuan-Hui,Li, Jin-Heng
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p. 222 - 227
(2019/11/13)
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- Method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene
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The invention discloses a method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene, and relates to the field of catalytic technology. The method comprises thefollowing steps: taking deionized water as a solvent and aldehyde as a reaction substrate, adding alkali into a reaction system, taking air as an oxidant and N-heterocyclic carbene as a catalyst required by the reaction, and carrying out catalytic oxidation on aldehyde at room temperature to 80 DEG C to generate a corresponding reaction product. The method has the beneficial effects that the N-heterocyclic carbene is used as the catalyst, no organic solvent is needed in the reaction process, the reaction process is green and safe, and the reaction yield is high.
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Paragraph 0039-0043; 0044-0047
(2020/11/25)
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- Method for producing aliphatic carboxylic acid compound and pyridine compound adduct of aliphatic ketone compound
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Provided are: a method for producing an aliphatic carboxylic acid compound safely and easily from a starting material that can be obtained or produced industrially without generating a harmful substance such as haloform; and a pyridine compound adduct of an aliphatic ketone compound. The method for producing an aliphatic carboxylic acid compound is a method for producing an aliphatic carboxylic acid compound represented by Formula (I), and comprises: a first step for obtaining a pyridine compound adduct by adding a pyridine compound to an aliphatic ketone compound having an alpha-methyl groupin the presence of an oxidizing agent; and a second step of hydrolyzing the pyridine compound adduct in the presence of a base. In the Formula, R1 represents a substituted or unsubstituted linear alkyl group having 4-8 carbon atoms or a substituted or unsubstituted branched alkyl group having 4-8 carbon atoms; M represents hydrogen, a metal belonging to Group 1 or Group 2 of the periodic table, amethyl group, an ethyl group, an n-propyl group or an isopropyl group.
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-
Paragraph 0172; 0175-0176; 0182; 0185-0186; 0192; 0195-0196
(2020/05/02)
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- Catalytic Oxidative Deamination by Water with H2Liberation
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Selective oxidative deamination has long been considered to be an important but challenging transformation, although it is a common critical process in the metabolism of bioactive amino compounds. Most of the synthetic methods developed so far rely on the use of stoichiometric amounts of strong and toxic oxidants. Here we present a green and efficient method for oxidative deamination, using water as the oxidant, catalyzed by a ruthenium pincer complex. This unprecedented reaction protocol liberates hydrogen gas and avoids the use of sacrificial oxidants. A wide variety of primary amines are selectively transformed to carboxylates or ketones in good to high yields. It is noteworthy that mechanistic experiments and DFT calculations indicate that in addition to serving as the oxidant, water also plays an important role in assisting the hydrogen liberation steps involved in amine dehydrogenation.
- Tang, Shan,Rauch, Michael,Montag, Michael,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 20875 - 20882
(2020/12/23)
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- Activated charcoal as an effective additive for alkaline and acidic hydrolysis of esters in water
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Activated charcoal largely enhanced the rates of the alkaline hydrolysis of methyl, ethyl, and n-propyl esters in aqueous 1.5 M NaOH solution to give the corresponding carboxylic acids in excellent yields. The acidic hydrolysis of methyl, ethyl, and n-propyl esters in aqueous 3 M H2SO4 solution was accelerated by the addition of activated charcoal to afford the corresponding carboxylic acids in good yields.
- Rohand, Taoufik,Tanemura, Kiyoshi
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supporting information
(2020/10/08)
-
- 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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- Multistep Engineering of Synergistic Catalysts in a Metal-Organic Framework for Tandem C-O Bond Cleavage
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Cleavage of strong C-O bonds without breaking C-C/C-H bonds is a key step for catalytic conversion of renewable biomass to hydrocarbon feedstocks. Herein we report multistep sequential engineering of orthogonal Lewis acid and palladium nanoparticle (NP) catalysts in a metal-organic framework (MOF) built from (Al-OH)n secondary building units and a mixture of 2,2′-bipyridine-5,5′-dicarboxylate (dcbpy) and 1,4-benzenediacrylate (pdac) ligands (1) for tandem C-O bond cleavage. Ozonolysis of 1 selectively removed pdac ligands to generate Al2(OH)(OH2) sites, which were subsequently triflated with trimethylsilyl triflate to afford strongly Lewis acidic sites for dehydroalkoxylation. Coordination of Pd(MeCN)2Cl2 to dcbpy ligands followed by in situ reduction produced orthogonal Pd NP sites in 1-OTf-PdNP as the hydrogenation catalyst. The selective and precise transformation of 1 into 1-OTf-PdNP was characterized step by step using powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, inductively coupled plasma mass spectrometry, infrared spectroscopy, and X-ray absorption spectroscopy. The hierarchical incorporation of orthogonal Lewis acid and Pd NP active sites endowed 1-OTf-PdNP with outstanding catalytic performance in apparent hydrogenolysis of etheric, alcoholic, and esteric C-O bonds to generate saturated alkanes via a tandem dehydroalkoxylation-hydrogenation process under relatively mild conditions. The reactivity of C-O bonds followed the trend of tertiary carbon > secondary carbon > primary carbon. Control experiments demonstrated the heterogeneous nature and recyclability of 1-OTf-PdNP and its superior catalytic activity over the homogeneous counterparts. Sequential engineering of multiple catalytic sites in MOFs thus presents a unique opportunity to address outstanding challenges in sustainable catalysis.
- Brzezinski, Carter,Chen, Justin S.,Feng, Xuanyu,Lin, Wenbin,Song, Yang,Xu, Ziwan
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supporting information
p. 4872 - 4882
(2020/04/01)
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- Non-metallic Aerobic Oxidation of Alcohols over Anthraquinone Based Compounds
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The catalytic performances of substituted anthraquinones were investigated in catalytic oxidation of alcohols like cyclohexanol, benzyl alcohol and 5-hydroxymethylfurfural (HMF) to carbonyl compounds (cyclohexanone, benzyl aldehyde and diformylfuran). The reduction potential of anthraquinone plays the key role in the oxidation reactions. TOF numbers and selectivities to carbonyl compounds pass through the maximum with increase of the reduction potential. The maximum activity and selectivity (>80 %) is observed for sulfonated and carboxylated anthraquinones having intermediate reduction potentials (≈ 0.1-0.2 V vs SHE). Grafted 2-carboxyanthraquinone catalyst has demonstrated comparable catalytic performance to the parent molecule and might be used as heterogeneous catalyst. The oxidation reaction was found to have radical character with transfer of hydrogen from alcohol to anthraquinone and subsequent oxidation of hydrogenated anthraquinone by oxygen.
- Zhao, Jingpeng,Wu, Dan,Hernández, Willinton Yesid,Zhou, Wen-Juan,Capron, Mickael,Ordomsky, Vitaly V.
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-
- Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides
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A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.
- Li, Chenchen,Li, Ruoling,Zhang, Bing,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 10913 - 10917
(2020/05/25)
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- PRODUCTION METHOD OF AMIDE COMPOUND
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PROBLEM TO BE SOLVED: To provide a production method of an amide compound, which can use a variety of carboxylic acid halides and can produce a desired amide compound at a yield higher than a batch process by suppressing a side reaction. SOLUTION: Provided is a production method of an amide compound using a flow type reactor, in which the flow type reactor includes: a first flow path; a second flow path; a first mixing means provided at a confluent part of the first flow path and the second flow path; and a third flow path that is connected to the first mixing means and arranged on a down stream side of the first mixing means, the production method comprising: a mixing step of obtaining a mixed liquid by circulating a first liquid containing the carboxylic acid halide in the first flow path, circulating a second liquid containing an amine compound having a molecular weight of 1,000 or less, an inorganic alkali and water in the second flow path, and mixing the first liquid and the second liquid by the first mixing means to obtain a mixture; and a reaction step of obtaining an amide compound by circulating the mixed liquid in the third flow path and reacting the carboxylic acid halide and the amine compound in the third flow path. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPO&INPIT
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Paragraph 0134-0137
(2020/10/08)
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- Molecularization of Bitter Off-Taste Compounds in Pea-Protein Isolates (Pisum sativum L.)
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Activity-guided fractionations, combined with taste dilution analyses (TDA), were performed to locate the key compounds contributing to the bitter off-taste of pea-protein isolates (Pisum sativum L.). Purification of the compounds perceived with the highe
- Gl?ser, Peter,Dawid, Corinna,Meister, Stefanie,Bader-Mittermaier, Stephanie,Schott, Michael,Eisner, Peter,Hofmann, Thomas
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p. 10374 - 10387
(2020/10/26)
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- Production of isobutyric acid from methanol by: Clostridium luticellarii
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Renewable methanol can be used as a feedstock to generate value-added multicarbon components through fermentation technologies. Recently, researchers reported the production of isobutyric acid using methanol as an electron donor with open culture systems dominated by Eubacterium sp. and Clostridium sp. Here we report the ability of Clostridium luticellarii wild-type strain to produce isobutyric acid from methanol and CO2 & H2. When growing on methanol, the supplementation of acetic and butyric acid enhanced isobutyric acid final concentration, selectivity and production rate. A maximum of 5.04 ± 0.08 g L-1 isobutyric acid was produced at a rate of 0.420 ± 0.012 g L-1 d-1and selectivity of 0.70 electron per electron of total products in batch with acetic and butyric acid as electron acceptors. The pH was also found to be a major factor influencing isobutyric acid formation with maximal production at pH 6.50. Finally, in addition to its ability to produce isomers, C. luticellarii was able to perform C2-unit elongation from methanol. Overall, this study positions C. luticellarii as a promising platform for the production of isocarboxylic acids.
- Petrognani, Camille,Boon, Nico,Ganigué, Ramon
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supporting information
p. 8389 - 8402
(2020/12/31)
-
- METHOD FOR THE HYDRODEOXYGENATION OF OXYGENATED COMPOUNDS TO UNSATURATED PRODUCTS
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The invention relates to methods of hydrodeoxygenation of oxygenated compounds into compounds with unsaturated carbon-carbon bonds, comprising the steps of: a) providing a reaction mixture comprising, an oxygenated compound containing one or more of a hydroxyl, keto or aldehyde group, an ionic liquid, a homogeneous metal catalyst, and carbon monoxide or a carbon monoxide releasing compound, b) reacting said reaction mixture under a H2 atmosphere at acidic conditions at a temperature between 180 and 250 °C and a pressure between 10 and 200 bar.
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-
Page/Page column 17
(2021/01/23)
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- Characterization of one novel microbial esterase WDEst9 and its use to make l-methyl lactate
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Chiral lactic acids and their ester derivatives are crucial building blocks and intermediates for the synthesis of a great variety of valuable functional materials and pharmaceuticals. Before our study, the reports about the enantioselective preparation of pure L-lactic acid and its ester derivatives through direct hydrolysis of racemic substrate were quite rare. Herein, we heterologously expressed and functionally characterized one novel microbial esterase WDEst9 from Dactylosporangium aurantiacum, which exhibited high resistance to diverse metal ions, organic solvents, surfactants, NaCl and KCl. We further utilized WDEst9 as a green biocatalyst in the kinetic resolution of (±)-methyl lactate through direct hydrolysis and generated L-methyl lactate with high enantiomeric excess (e.e. >99%) and high yield (>86%) after process optimization. Notably, the enantioselectivity of WDEst9 was opposite than that of two previously reported esterases PHE14 and BSE01701 that can generate D-methyl lactate though kinetic resolution of (±)-methyl lactate. Microbial esterase WDEst9 is a promising green biocatalyst in the preparation of valuable chiral chemicals and opens the door for the identification of useful industrial enzymes and biocatalysts from the genus Dactylosporangium.
- Wang, Yilong,Xu, Shan,Li, Renqiang,Sun, Aijun,Zhang, Yun,Sai, Ke,Hu, Yunfeng
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p. 190 - 200
(2018/12/11)
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- Chemoenzymatic Cascade Synthesis of Optically Pure Alkanoic Acids by Using Engineered Arylmalonate Decarboxylase Variants
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Arylmalonate decarboxylase (AMDase) catalyzes the cofactor-free asymmetric decarboxylation of prochiral arylmalonic acids and produces the corresponding monoacids with rigorous R selectivity. Alteration of catalytic cysteine residues and of the hydrophobic environment in the active site by protein engineering has previously resulted in the generation of variants with opposite enantioselectivity and improved catalytic performance. The substrate spectrum of AMDase allows it to catalyze the asymmetric decarboxylation of small methylvinylmalonic acid derivatives, implying the possibility to produce short-chain 2-methylalkanoic acids with high optical purity after reduction of the nonactivated C=C double bond. Use of diimide as the reductant proved to be a simple strategy to avoid racemization of the stereocenter during reduction. The developed chemoenzymatic sequential cascade with use of R- and S-selective AMDase variants produced optically pure short-chain 2-methylalkanoic acids in moderate to full conversion and gave both enantiomers in excellent enantiopurity (up to 83 % isolated yield and 98 % ee).
- Enoki, Junichi,Mügge, Carolin,Tischler, Dirk,Miyamoto, Kenji,Kourist, Robert
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p. 5071 - 5076
(2019/03/17)
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- A Supramolecular Strategy for Selective Catalytic Hydrogenation Independent of Remote Chain Length
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Performing selective transformations on complex substrates remains a challenge in synthetic chemistry. These difficulties often arise due to cross-reactivity, particularly in the presence of similar functional groups at multiple sites. Therefore, there is a premium on the ability to perform selective activation of these functional groups. We report here a supramolecular strategy where encapsulation of a hydrogenation catalyst enables selective olefin hydrogenation, even in the presence of multiple sites of unsaturation. While the reaction requires at least one sterically nondemanding alkene substituent, the rate of hydrogenation is not sensitive to the distance between the alkene and the functional group, including a carboxylate, on the other substituent. This observation indicates that only the double bond has to be encapsulated to effect hydrogenation. Going further, we demonstrate that this supramolecular strategy can overcome the inherent allylic alcohol selectivity of the free catalyst, achieving supramolecular catalyst-directed regioselectivity as opposed to directing-group selectivity.
- Bender, Trandon A.,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
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supporting information
p. 11806 - 11810
(2019/08/22)
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- Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
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The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
- Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 14365 - 14373
(2019/09/06)
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- Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source
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The general dehalogenation of alkyl halides with zinc using D2O or H2O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.
- Xia, Aiyou,Xie, Xin,Hu, Xiaoping,Xu, Wei,Liu, Yuanhong
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p. 13841 - 13857
(2019/10/17)
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- Highly active bidentate N-heterocyclic carbene/ruthenium complexes performing dehydrogenative coupling of alcohols and hydroxides in open air
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Eight bidentate NHC/Ru complexes, namely [Ru]-1-[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
- Wang, Zhi-Qin,Tang, Xiao-Sheng,Yang, Zhao-Qi,Yu, Bao-Yi,Wang, Hua-Jing,Sang, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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supporting information
p. 8591 - 8594
(2019/07/25)
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- Direct oxidative esterification of primary alcohols and oxidation of secondary alcohols over mesoporous spherical silica encapsulated MnO2 nanoparticles
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In this work, a simple and efficient strategy for the fabrication of novel encapsulated MnO2 nanoparticles inside spherical mesoporous silica hollow-nanoparticles was described. They were synthesized by consecutively anchoring MnO2 nanoparticles on poly(styrene-co-methacrylic acid) particles, coating with a mesoporous silica shell, and subsequently removing the polymeric core by dissolving in acetone. The catalytic activity of the nanoparticles was examined in the aerobic oxidation of various primary and secondary alcohols, which showed good activity and selectivity for the transformation of primary alcohols to the corresponding esters through the oxidative esterification process and secondary alcohols to ketones in short reaction times under mild reaction conditions. In addition, the catalyst system was utilized for the oxidation of primary alcohols to aldehydes using tert-butyl hydroperoxide (TBHP) as an oxidant under mild conditions and produced an excellent product yield.
- Hosseinzadeh, Shahram Zare,Babazadeh, Mirzaagha,Shahverdizadeh, Gholam Hossein,Hosseinzadeh-Khanmiri, Rahim
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p. 9491 - 9499
(2019/06/21)
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- Fe3O4@SiO2@Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime
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An efficient and environmentally friendly oxidation process for the one-pot preparation of oxime, imine and carbonyl compounds through alcohol oxidation in the presence of H2O2 and/or O2 have been developed by a melamine-Mn(III) Schiff base complex supported on Fe3O4@SiO2–Cl nanoparticles, named as Fe3O4@SiO2@Im[Cl]Mn(III)-complex nanocomposite, at room temperature. Direct oxidation of alcohol to carboxylic acid was performed using the catalyst in the presence of molecular O2 at room temperature in a different approach. The oxidation products were obtained with excellent yields and high TOFs. The properties of the catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (C, H, N), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP), cyclic voltammetry (CV), nuclear magnetic resonance (1H & 13C NMR), vibration sample magnetometer (VSM), Brunauer– Emmett–Teller (BET) and differential pulse voltammetry (DPV) analyses. The mechanism of the oxidation processes was investigated for the both H2O2 and O2 oxidants. The role of the imidazolium moiety in the catalyst as a secondary functionality was investigated. Chemoselectivity behavior of the catalyst was studied by some combinations. The catalyst could be recycled from the reaction mixture by a simple external magnet and reused for several times without any considerable reactivity loss.
- Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
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p. 230 - 249
(2019/03/28)
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- Bidentate Ru(ii)-NC complexes as catalysts for the dehydrogenative reaction from primary alcohols to carboxylic acids
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Four Ru(ii)-NC complexes were synthesized by one-step processes from the corresponding NC ligands with RuHCl(CO)(PPh3)3. These complexes were tested as catalysts for alcohol dehydrogenative reactions, and complex {(C5H4N)-(C6H4)}RuCl(CO)(PPh3)2 (1) showed the highest activity. With KOH as the nucleophile and 0.5 mol% catalyst loading, a series of carboxylic acids were synthesized in toluene without any oxidant. Catalyst 1 could be transformed to complex {(C5H4N)-(C6H4)}RuH(CO)(PPh3)2 (6) when treated with KOH and benzyl alcohol. Complex 6 further reacted with PhCHO and H2O to generate product {(C5H4N)-(C6H4)}Ru(OCOPh)(CO)(PPh3)2 (7). Complexes 6 and 7 exhibited similar efficiency to complex 1, suggesting that they can be regarded as the catalytic intermediates of 1.
- Gong, Dawei,Hu, Bowen,Chen, Dafa
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p. 8826 - 8834
(2019/06/24)
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