- Tunable System for Electrochemical Reduction of Ketones and Phthalimides
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Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3/HN3 cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
- Chen, Gong,Qiao, Tianjiao,Wang, Yaxin,Zhang, Jian,Zhao, Jianyou
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supporting information
p. 3297 - 3302
(2021/10/14)
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- Biocatalysed reductions of α-ketoesters employing CyreneTM as cosolvent
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The search for novel reaction media with environmental friendly properties is an area of great interest in enzyme catalysis. Water is the medium of biocatalysed processes, but due to its properties, sometimes the presence of organic (co)solvents is required. CyreneTM represents one of the newest approaches to this medium engineering. This polar solvent has been employed for the first time in biocatalysed reductions employing purified alcohol dehydrogenases. A set of α-ketoesters has been reduced to the corresponding chiral α-hydroxyesters with high conversions and optical purities, being possible to obtain good results at Cyrene contents of 30% v/v and working at substrate concentrations of 1.0 M in presence of 2.5% v/v of this solvent. At this concentration, the presence of Cyrene has a beneficial effect in the bioreduction conversion.
- de Gonzalo, Gonzalo
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- Preparation of Organic Nitrates from Aryldiazoacetates and Fe(NO3)3·9H2O
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A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
- Thurow, Samuel,Fernandes, Alessandra A. G.,Quevedo-Acosta, Yovanny,De Oliveira, Matheus F.,De Oliveira, Marcelo G.,Jurberg, Igor D.
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p. 6909 - 6913
(2019/09/12)
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- Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
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Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
- Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
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supporting information
p. 14499 - 14503
(2019/09/17)
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- Strongly enhanced acidity and activity of amorphous silica–alumina by formation of pentacoordinated AlV species
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Tailoring high-performance aluminosilicates plays a key role in the efficient and clean production of high-value chemicals. Recent work reveals that pentacoordinated Al (AlV) species can significantly enhance the Br?nsted acidity of amorphous silica–alumina (ASA), compared with that typically dominated by tetracoordinated Al species. However, the controlled synthesis of AlV-rich ASAs is challenging. Employing xylene as the solvent in a flame-spray pyrolysis process, we synthesized AlV-rich ASAs successfully. The high combustion enthalpy of xylene (36.9 kJ/ml) results in a high flame temperature, promoting the formation and distribution of metastable AlV species in the silica network forming Br?nsted acid sites. This provides a promising route for the controlled synthesis of AlV-rich ASAs with higher Br?nsted acidity. As an example, AlV-rich ASAs are shown to exhibit superior catalytic performance in phenylglyoxal conversion to ethyl mandelate in ethanol compared with that achieved with other acid catalysts, attaining an ethyl mandelate yield of 99.8%.
- Wang, Zichun,Jiang, Yijiao,Jin, Fangzhu,Stampfl, Catherine,Hunger, Michael,Baiker, Alfons,Huang, Jun
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- Cobalt-Catalyzed Transfer Hydrogenation of α-Ketoesters and N-Cyclicsulfonylimides Using H2O as Hydrogen Source
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A Co-catalyzed effective transfer hydrogenation of various α-ketoesters and N-cyclicsulfonylimides by safe and environmentally benign H2O as hydrogen source is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N-cyclicsulfonylimides. (Figure presented.).
- Gao, Yang,Zhang, Xuexin,Laishram, Ronibala Devi,Chen, Jingchao,Li, Kangkui,Zhang, Keyang,Zeng, Guangzhi,Fan, Baomin
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supporting information
p. 3991 - 3997
(2019/08/02)
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- Electrochemical Hydrogenation with Gaseous Ammonia
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As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
- Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
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supporting information
p. 1759 - 1763
(2019/01/16)
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- Mild and efficient rhodium-catalyzed deoxygenation of ketones to alkanes
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A new and simple method for the deoxygenation of ketones to alkanes is presented. Most substrates are reduced under mild conditions by triethylsilane in the presence of catalytic amounts of [Rh(μ-Cl)(CO)2]2. This system selectively provides the methylene hydrocarbons in good to excellent yields starting from acetophenones and diaryl ketones. A rapid examination of the reaction pathway suggests that the ketone is first converted into an alcohol, which then undergoes hydrogenolysis to give the alkane.
- Argouarch, Gilles
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supporting information
p. 11041 - 11044
(2019/07/31)
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- Boron-Catalyzed O-H Bond Insertion of α-Aryl α-Diazoesters in Water
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A catalytic, metal-free O-H bond insertion of α-diazoesters in water in the presence of B(C6F5)3·nH2O (2 mol %) was developed, affording a series of α-hydroxyesters in good to excellent yields. The reaction features easy operation and wide substrate scope, and importantly, no metal is needed as compared with the conventional methods. Significantly, this approach further expands the applications of B(C6F5)3 under water-tolerant conditions.
- San, Htet Htet,Wang, Shi-Jun,Jiang, Min,Tang, Xiang-Ying
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p. 4672 - 4676
(2018/08/09)
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- A benzo b furyl ketone dye synthesis method (by machine translation)
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The invention relates to a of benzodifaradone dye synthesis method, first to the manufacture of chlorine list alkyl esters, aromatic hydrocarbon as the raw material for Friedel-crafts reaction intermediates 1 or 1 ', then the intermediate 1, intermediate 1' hydrogenation reduction for preparing intermediate 2 and intermediate 2 ', intermediate 2 with condensation product of [...] intermediate 3 with the intermediate 2' condensation reaction to produce intermediate 4, intermediate 4 is oxidized to obtain the benzo b butenolides. The present invention provides a process for synthesis of low cost, low risk, low pollution, the process route is simple without a separate purification process; production and cheap, the cost is far lower than the existing technology, and the product higher total yield can be up to 69%, content is greater than 98.5%, has extremely high economic efficiency, and is suitable for large-scale production, it has good industrial application prospect. (by machine translation)
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- Iridium-catalyzed efficient reduction of ketones in water with formic acid as a hydride donor at low catalyst loading
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A highly efficient and chemoselective transfer hydrogenation of ketones in water has been successfully achieved with our newly developed catalyst. Simple ketones, as well as α- or β-functionalized ketones, are readily reduced. Formic acid is used as a traceless hydride source. At very low catalyst loading (S/C = 10:000 in most cases; S/C = 50:000 or 100:000 in some cases), the iridium catalyst is impressively efficient at reducing ketones in good to excellent yields. The TOF value can be as high as up to 26:000 mol mol-1 h-1. A variety of functional groups are well tolerated, for example, heteroaryl, aryloxy, alkyloxy, halogen, cyano, nitro, ester, especially acidic methylene, phenol and carboxylic acid groups.
- Liu, Ji-Tian,Yang, Shiyi,Tang, Weiping,Yang, Zhanhui,Xu, Jiaxi
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supporting information
p. 2118 - 2124
(2018/05/24)
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- Chemoselective reduction of aldehydes and ketones by potassium diisobutyl-t-butoxy aluminum hydride (PDBBA)
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t-Butoxy derivatives of DIBALH [lithium diisobutyl-t-butoxyaluminum hydride (LDBBA), sodium diisobutyl-t-butoxyaluminum hydride (SDBBA), and potassium diisobutyl-t-butoxyaluminum hydride (PDBBA)] were examined as chemoselective reducing agents of carbonyl compounds. Among them, PDBBA was found to be the most efficient for the reduction of aldehydes and ketones to the corresponding alcohols in the presence of ester, amide, and nitrile substituents at ambient temperature. In addition, the optimal conditions gave higher chemoselectivity for aldehydes in the presence of ketones.
- Kim, Joo Yeon,Shin, Won Kyu,Jaladi, Ashok Kumar,An, Duk Keun
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p. 4236 - 4241
(2018/06/30)
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- Mechanism of Enolate Transfer between Si and Cu
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Exchange of X (F, Cl, OMe) and a substituted enolate chain between SiMe3 and various CuI complexes was examined. Reaction mechanisms pass through a cyclic transition state in which the reaction coordinate is associated with rotation of the SiMe3 moiety. The dependence of the thermodynamic and kinetic features on the nature of the active and ancillary ligands was examined. Formation of copper enolate is shown to be favored when stabilized enolates are used. Replacement of F by Cl reverses the preference of the reaction. This is associated with the small difference between the Cu?Cl and Si?Cl bond energies, in contrast to other Si?X bonds, which are systematically stronger than their Cu?X analogues.
- Bouaouli, Samira,Spielmann, Kim,Vrancken, Emmanuel,Campagne, Jean-Marc,Gérard, Hélène
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supporting information
p. 6617 - 6624
(2018/04/19)
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- Zirconocene-catalyzed direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio under solvent-free conditions
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A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C-Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.
- Tang, Zhi,Jiang, Qiutao,Peng, Lifen,Xu, Xinhua,Li, Jie,Qiu, Renhua,Au, Chak-Tong
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supporting information
p. 5396 - 5402
(2017/11/22)
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- Mandelic acid derived ionic liquids: synthesis, toxicity and biodegradability
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A series of ten ionic liquids (ILs) was synthesised from the renewable resource mandelic acid. The ILs showed low antimicrobial activity towards the thirteen bacterial and twelve fungal strains they were screened against. A general trend of increasing bacterial toxicity in the order methyl ester 60% in 28 days), a series of biodegradation transformation products has been proposed based on the degradation of the ester/amide alkyl chain. This data has allowed for an assessment of the effect of IL structural features on toxicity and biodegradation, particularly allowing for a comparison to earlier work where additional oxygen atoms were present to facilitate biodegradation and attenuate toxicity. The mandelic acid derived ILs did not pass the Closed Bottle test (OECD 301D) and can be included in the rules of thumb for the design of biodegradable ILs.
- Prydderch, Hannah,Haiβ, Annette,Spulak, Marcel,Quilty, Brid,Kümmerer, Klaus,Heise, Andreas,Gathergood, Nicholas
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p. 2115 - 2126
(2017/01/22)
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- A carbonyl reductase from: Candida parapsilosis ATCC 7330: Substrate selectivity and enantiospecificity
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Candida parapsilosis ATCC 7330, a rich source of highly stereospecific oxidoreductases, catalyzes oxidation-reduction of a plethora of compounds yielding industrially important intermediates. An (S)-specific carbonyl reductase (SRED) purified and characterized from this yeast is reported here. (R)-Specific carbonyl reductase (CpCR) was reported by us earlier. SRED asymmetrically reduces ketones with excellent enantiospecificity (ee > 99%) and α-ketoesters with higher catalytic activity but moderate enantiospecificity (ee 70%) in the presence of NADPH. Minimal activity is shown towards the reduction of aldehydes. While the reduction of α-ketoesters with SRED can occur with either NADPH or NADH, for ketone reduction SRED requires NADPH specifically. SRED with a subunit molecular weight of 30 kDa shows optimal activity at pH 5.0 and 25 °C, and its activity is affected by Cu2+. Taken together, SRED and CpCR offer substrates which on asymmetric reduction give products of opposite absolute configurations.
- Sudhakara, Sneha,Chadha, Anju
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supporting information
p. 4165 - 4171
(2017/07/10)
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- Identification of a New Zinc Binding Chemotype by Fragment Screening
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The discovery of a new zinc binding chemotype from screening a nonbiased fragment library is reported. Using the orthogonal fragment screening methods of native state mass spectrometry and surface plasmon resonance a 3-unsubstituted 2,4-oxazolidinedione fragment was found to have low micromolar binding affinity to the zinc metalloenzyme carbonic anhydrase II (CA II). This affinity approached that of fragment sized primary benzenesulfonamides, the classical zinc binding group found in most CA II inhibitors. Protein X-ray crystallography established that 3-unsubstituted 2,4-oxazolidinediones bound to CA II via an interaction of the acidic ring nitrogen with the CA II active site zinc, as well as two hydrogen bonds between the oxazolidinedione ring oxygen and the CA II protein backbone. Furthermore, 3-unsubstituted 2,4-oxazolidinediones appear to be a viable starting point for the development of an alternative class of CA inhibitor, wherein the medicinal chemistry pedigree of primary sulfonamides has dominated for several decades.
- Chrysanthopoulos, Panagiotis K.,Mujumdar, Prashant,Woods, Lucy A.,Dolezal, Olan,Ren, Bin,Peat, Thomas S.,Poulsen, Sally-Ann
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p. 7333 - 7349
(2017/09/22)
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- Α-chloro -4 fluoro phenyl benzylone method for the synthesis of
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The invention relates to the field of chemistry, particularly to the field of medicinal chemistry, more particularly to a synthetic method for alpha-chlorine-4fluorine phenyl benzyl ketone, and aims to solve the problems that in the traditional preparation technology, the cost for preparing phenylacetic acid synthetic compound is high, the technology is complicated and the technology is not suitable for industrial production. The invention provides a novel synthetic method for alpha-chlorine-4fluorine phenyl benzyl ketone through adopting mandelic acid, which includes the following steps: alpha position chloro takes as the first step reaction, corresponding synthetic parameters are matched, and the mandelic acid takes as a starting material for synthesizing compound (4). Therefore, the total yield reaches 67.8% after three-step synthesis, by-products generated in the reaction are reduced, the purity of a target object is high, the purification is easy, and the method is suitable for industrial production.
- -
-
Paragraph 0026; 0027
(2017/04/28)
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- Reactions of a novel modified Red-Al reducing agent with selected organic compounds containing representative functional groups and chemoselective reduction
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A new modified Red-Al reagent prepared from commercially available 1,1,1,3,3,3-hexamethyldisilazane and sodium bis(2-methoxyethoxy)aluminumhydride (Red-Al) is reported for the selective reduction of carbonyl compounds containing representative functional groups. Moreover, this novel reagent is superior for the chemoselective reduction of aldehydes and ketones to the corresponding alcohols in excellent yields under mild reaction conditions. Moreover, aldehydes can be reduced selectively in the presence of ketones with similar reactivity.
- Park, Ji Yeon,Shin, Won Kyu,Jaladi, Ashok Kumar,An, Duk Keun
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p. 3247 - 3251
(2016/07/11)
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- Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2
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A novel, in-situ synthesis of dichlorotriphenylphosphorane (Ph3PCl2) is accomplished upon combining PPh3and the easily prepared hypervalent iodine reagent iodobenzene dichloride (PhICl2). The phosphorane is selectively generated in the presence of carboxylic acid or alcohol residues to rapidly produce acyl chlorides and alkyl chlorides in high yields. Addition of EtOH, PhOH, BnOH, Et2NH or CH2N2results in the direct synthesis of esters, amides and diazo ketones from carboxylic acids.
- Carle, Myriam S.,Shimokura, Grace K.,Murphy, Graham K.
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supporting information
p. 3930 - 3933
(2016/08/24)
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- Copper-Carbene Intermediates in the Copper-Catalyzed Functionalization of O-H Bonds
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Copper-carbene [TpxCu=C(Ph)(CO2Et)] and copper-diazo adducts [TpxCu{η1-N2C(Ph)(CO2Et)}] have been detected and characterized in the context of the catalytic functionalization of O-H bonds through carbene insertion by using N2=C(Ph)(CO2Et) as the carbene source. These are the first examples of these type of complexes in which the copper center bears a tridentate ligand and displays a tetrahedral geometry. The relevance of these complexes in the catalytic cycle has been assessed by NMR spectroscopy, and kinetic studies have demonstrated that the N-bound diazo adduct is a dormant species and is not en route to the formation of the copper-carbene intermediate.
- Pereira, Ana,Champouret, Yohan,Martín, Carmen,álvarez, Eleuterio,Etienne, Michel,Belderraín, Tomás R.,Pérez, Pedro J.
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supporting information
p. 9769 - 9775
(2015/06/30)
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- Chiral spiro-pyridylamidophosphine ligand compound, synthesis method therefor and application thereof
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The present invention relates to a chiral spiro-pyridylamidophosphine ligand compound, synthesis method therefor and application thereof. The chiral spiro-pyridylamidophosphine compound is a compound having a structure of Formula (I), a racemate or optical isomer thereof, or a catalytically acceptable salt thereof, and is mainly characterized by having a chiral spiro-dihydro-indene skeleton in its structure. The chiral spiro-pyridylamidophosphine compound may be synthesized with optical active 7-diaryl/alkylphosphino-7′-amino-1,1′-spiro-dihydro-indene or substituted 7-diaryl/alkylphosphino-7′-amino-1,1′-spiro-dihydro-indene having a spiro-skeleton as chiral starting material. The chiral spiro-pyridylamidophosphine compound may be used as a chiral ligand in asymmetric hydrogenation of a carbonyl compound catalyzed by iridium, in which the reaction activity is very high, the amount of the catalyst may be 0.0001 mol %, and the enantioselectivity of the reaction is up to 99.9% ee.
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Page/Page column 17; 18-20
(2015/03/03)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
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- Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water
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Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, β-keto esters and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. Water wonder: Iridicycle catalysts are versatile and allow the highly efficient and chemoselective transfer hydrogenation of a variety of carbonyl compounds, including problematic and challenging ones, with formate in neat water (see scheme).
- Talwar, Dinesh,Wu, Xiaofeng,Saidi, Ourida,Salguero, Noemí Poyatos,Xiao, Jianliang
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supporting information
p. 12835 - 12842
(2015/03/30)
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- Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
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Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against the measured substrate volumes we observed that apart from the substrate size other effects must be responsible for the activity obtained. Compared to acetophenone (100% relative activity), other small substrates such as propiophenone, α,α, α-trifluoroacetophenone, α-hydroxyacetophenone, and benzoylacetonitrile had relative activities lower than 30%, while medium-sized ketones such as α-bromo-, α,α-dichloro-, and α,α-dibromoacetophenone presented relative activities between 70% and 550%. Moreover, the comparison between the enzymatic activity and the obtained final conversions using an excess or just 2.5 equiv. of the hydrogen donor 2-propanol, denoted again deviations between them. These data supported that these hydrogen transfer (HT) transformations are mainly thermodynamically controlled. For instance, bulky α-halogenated derivatives could be quantitatively reduced by LBADH even employing 2.5 equiv. of 2-propanol independently of their kinetic values. Finally, we found good correlations between the IR absorption band of the carbonyl groups and the degrees of conversion obtained in these HT processes, making this simple method a convenient tool to predict the success of these transformations. The Royal Society of Chemistry.
- Rodriguez, Cristina,Borzecka, Wioleta,Sattler, Johann H.,Kroutil, Wolfgang,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 673 - 681
(2014/01/06)
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- Kinetics and catalyst deactivation in the enantioselective hydrogenation of ethyl benzoylformate over Pt/Al2O3
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The enantioselective hydrogenation of ethyl benzoylformate (EBF) to (R)-ethyl mandelate(-)-cinchonidine (CD)-modified Pt/Al2O 3 catalyst in toluene in a semi-batch reactor was studied as a function of modifier concentration, reaction temperature, stirring rate and catalyst particle size. The kinetic results showed higher enantioselectivity and lower initial rates tending asymptotically to a constant value as the amount of modifier increased. The maximum enantiomeric excess (ee) and the initial hydrogenation rate or turnover frequency obtained under optimized conditions with an initial concentration of 5.6 mmol L-1 EBF at 25°C5% (w/w) Pt/Al2O3 were 85% (modifier-to-surface Pt of 1.28) and 109 h-1 (modifier-to-surface Pt of 0.16), respectively. Additionally, catalyst deactivation due to the presence of impurities in the feed was prominent in some cases; therefore activated carbon was used as a cleaning agent of the raw material to remove impurities prior to catalyst addition.
- Martin, Gerson,Maeki-Arvela, Paeivi,Murzin, Dmitry Yu.,Salmi, Tapio
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p. 170 - 178
(2014/01/06)
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- Enantio- and chemoselective Br?nsted-acid/Mg(nBu) 2 catalysed reduction of α-keto esters with catecholborane
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The first enantio- and chemoselective Br?nsted-acid catalysed reduction of α-keto esters with catecholborane has been developed. The α-hydroxy esters were obtained under mild reaction conditions in virtually quantitative yields and excellent enantioselectivities. With slight modifications both enantiomers can be obtained without any loss of selectivity. This journal is the Partner Organisations 2014.
- Enders, Dieter,St?ckel, Bianca A.,Rembiak, Andreas
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supporting information
p. 4489 - 4491
(2014/04/17)
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- On the thermal Pummerer rearrangement of substituted sulfoxides
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Sulfoxides bearing thioester and ester groups at the position under heating at ca. 140C undergo Pummerer thermal rearrangement. However, for sulfonyl sulfoxide, a complex mixture of products is formed. Plausible mechanism is advanced(equation presented. 2013
- Marzorati, Liliana,Yoshikawa, Eduardo K.C.,Braga, Ataualpa A.C.,Di Vitta, Claudio
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p. 248 - 260
(2014/04/03)
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- Asymmetric catalytic arylation of ethyl glyoxylate using organoboron reagents and Rh(i)-phosphane and phosphane-phosphite catalysts
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Herein we report the first application of Rh(i)-phosphane and phosphane-phosphite catalysts in the enantioselective catalytic arylation of ethyl glyoxylate with organoboron reagents, providing access to ethyl mandelate derivatives in high yield (up to 99%) and moderate to very good enantioselectivities (up to 75% ee). Commercial phosphane ligands, such as (R)-MonoPhos and (R)-Phanephos were tested, as well as non-commercial (R,R)-TADDOL-derived phosphane-phosphite ligands. Those ligands containing bulky substituents in the ortho-and para-positions of the chiral phosphite moiety were found to be the most selective.
- Marques, Carolina Silva,Dindaroglu, Mehmet,Schmalz, Hans-Guenther,Burke, Anthony J.
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p. 6035 - 6041
(2014/01/23)
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- Efficient acid-catalyzed conversion of phenylglyoxal to mandelates on flame-derived silica/Alumina
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Amorphous, nonporous silica/alumina (SA) made by flame-spray pyrolysis (FSP) efficiently catalyzes the direct conversion of phenylglyoxal (PG) to alkyl mandelates. The SAs exhibited a turnover frequency more than an order of magnitude higher than dealuminated zeolite Y, which hitherto has been considered as the most active solid acid for this reaction. The free diffusion of PG to surface acid sites and rapid removal of mandelate products are proposed to be at the origin of the superior performance of SAs. The recyclability of the catalyst was tested in five repetitive runs and showed no significant loss of catalyst performance.
- Wang, Zichun,Jiang, Yijiao,Baiker, Alfons,Huang, Jun
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p. 1573 - 1577
(2013/07/26)
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- One-step room-temperature synthesis of [Al]MCM-41 materials for the catalytic conversion of phenylglyoxal to ethylmandelate
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Mesoporous [Al]MCM-41 materials with nSi/nAl ratios of 15 to 50 suitable for the direct catalytic conversion of phenylglyoxal to ethylmandelate have been successfully synthesized at room temperature within 1 h. The surface areas and pore sizes of the obtained [Al]MCM-41 materials are in the ranges of 1005-1246 m2 g-1 and 3.44-3.99 nm, respectively, for the different nSi/nAl ratios. For all [Al]MCM-41 catalysts, most of the Al species were tetrahedrally coordinated with Si in the next coordination sphere of atoms. 1H and 13C magic-angle spinning NMR spectroscopic investigations indicated that the acid strength of the SiOH groups on these [Al]MCM-41 catalysts and the density of these surface sites are enhanced with increasing Al content in the synthesis gels. These surface sites with enhanced acid strength were found to be catalytically active sites for phenylglyoxal conversion. The [Al]MCM-41 material with nSi/nAl=15 showed the highest phenylglyoxal conversion (93.4 %) and selectivity to ethylmandelate (96.9 %), whereas the [Al]MCM-41 material with nSi/nAl=50 reached the highest turnover frequency (TOF=99.3 h-1). This is a much better catalytic performance than that of a dealuminated zeolite Y (TOF=1.7 h-1) used as a reference catalyst, which is explained by lower reactant transport limitations in mesoporous materials than that in the microporous zeolite. Mesopores flex their catalytic muscles: Mesoporous [Al]MCM-41 materials with nSi/nAl ratios of 15 to 50 suitable for the direct catalytic conversion of phenylglyoxal to ethylmandelate were successfully synthesized at room temperature within 1 h. Copyright
- Wang, Zichun,Jiang, Yijiao,Rachwalik, Rafal,Liu, Zhongwen,Shi, Jeffrey,Hunger, Michael,Huang, Jun
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p. 3889 - 3896
(2014/01/06)
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- SNAAP sulfonimidate alkylating agent for acids, alcohols, and phenols 1
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Stable, crystalline ethyl N-tert-butyl-4-nitrobenzenesulfonimidate has been prepared in high yield by direct O-ethylation of N-tert-butyl-4- nitrobenzenesulfonamide with iodoethane and silver(I) oxide in dichloromethane. This sulfonimidate directly ethylates various acids to esters; the stronger the acid, the faster it alkylates and in higher yield. It readily ethylates alcohols and phenols to ethers at room temperature in the presence of tetrafluoroboric acid catalyst without molecular rearrangements or racemization. We have defined these reactions as SNAAP alkylations: [substitution, nucleophilic of acids, alcohols and phenols]. The hard sulfonimidate alkylating agent is chemoselective, preferring oxygen > nitrogen > sulfur. The sulfonamide byproduct of alkylation is readily recycled to the sulfonimidate. Georg Thieme Verlag Stuttgart . New York.
- Maricich, Tom J.,Allan, Matthew J.,Kislin, Brett S.,Chen, Andrea I-T.,Meng, Fan-Chun,Bradford, Christine,Kuan, Nai-Chia,Wood, Jeremy,Aisagbonhi, Omonigho,Poste, Alethea,Wride, Dustin,Kim, Sylvia,Santos, Therese,Fimbres, Michael,Choi, Dianne,Elia, Haydi,Kaladjian, Joseph,Abou-Zahr, Ali,Mejia, Arturo
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p. 3361 - 3368
(2014/01/06)
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- Iron-catalyzed hydrogenation for the in situ regeneration of an NAD(P)H model: Biomimetic reduction of α-Keto-/α-iminoesters
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Two irons for a smoother finish: An NAD(P)H model was regenerated readily in situ by iron-catalyzed reduction with molecular hydrogen. The subsequent biomimetic reduction of α-keto-/ α-iminoesters proceeded smoothly in the presence of an iron-based Lewis acid (LA) to provide α-hydroxyesters and amino acid esters in good to excellent yields (see scheme; NAD(P) +=nicotinamide adenine dinucleotide (phosphate), TM=transition metal). Copyright
- Lu, Liang-Qiu,Li, Yuehui,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8382 - 8386
(2013/09/02)
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- Design, synthesis, and anticonvulsant screening of some substituted piperazine and aniline derivatives of 5-phenyloxazolidin- 2,4-diones and 5,5-diphenylimidazolidin-2,4 diones
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Substituted piperazine and aniline derivatives of oxazolidin-2,4-diones and imidazolidin-2,4-diones were synthesized by N3 alkylation and screened for their anticonvulsant activity by the maximal electroshock (MES) test, and their neurotoxicity was evaluated by the rotarod test. Among all the synthesized derivatives, compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d were found to exhibit maximum seizure protection in MES test and were devoid of any neurotoxic effects. Furthermore, the functional activity of these compounds were evaluated in vivo for 5-HT1A receptor affinity by using rectal body temperature and lower lip retraction in rats, while head twitch response in mice was performed for the determination of probable affinity toward HT2A receptor. The results of these tests demonstrated that compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d exhibited 5-HT1A (pre- and postsynaptic) agonist/ antagonist features whereas compounds 11a and 11b exhibited antagonist action for HT2A receptor. From the in vivo studies it was observed that a majority of aniline derivatives (6c, 6d, 11a, 11b, 11d) were found to be more active as compared to their bulky piperazine congeners (4b, 10b). Thus, the overall reduction in the bulkiness of the derivatives without compromising the lipophilicity is well appreciated for providing insights into the structural requirements necessary for development of new effective molecules having anticonvulsant effect.
- Dhanawat, Meenakshi,Banerjee, Anupam G.,Shrivastava, S. K.
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p. 2807 - 2822,16
(2020/07/30)
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- COMPOUNDS FOR THE REDUCTION OF β-AMYLOID PRODUCTION
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The present disclosure provides a series of compounds of the formula (I), which modulate β-amyloid peptide (β-ΑΡ) production and are useful in the treatment of Alzheimer's Disease and other conditions affected by β-amyloid peptide (β-ΑΡ) production.
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Page/Page column 92-93
(2012/08/08)
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- Direct, redox-neutral prenylation and geranylation of secondary carbinol C-H bonds: C4-regioselectivity in ruthenium-catalyzed C-C couplings of dienes to α-hydroxy esters
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The ruthenium catalyst generated in situ from Ru3(CO) 12 and tricyclohexylphosphine, PCy3, promotes the redox-neutral C-C coupling of aryl-substituted α-hydroxy esters to isoprene and myrcene at the diene C4-position, resulting in direct carbinol C-H prenylation and geranylation, respectively. This process enables direct conversion of secondary to tertiary alcohols in the absence of stoichiometric byproducts or premetalated reagents, and is the first example of C4-regioselectivity in catalytic C-C couplings of 2-substituted dienes to carbonyl partners. Mechanistic studies corroborate a catalytic cycle involving diene-carbonyl oxidative coupling.
- Leung, Joyce C.,Geary, Laina M.,Chen, Te-Yu,Zbieg, Jason R.,Krische, Michael J.
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supporting information
p. 15700 - 15703
(2012/11/07)
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- General and efficient α-oxygenation of carbonyl compounds by TEMPO induced by single-electron-transfer oxidation of their enolates
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A generally applicable method for the synthesis of protected α-oxygenated carbonyl compounds is reported. It is based on the single-electron-transfer oxidation of easily generated enolates to the corresponding α-carbonyl radicals. Coupling with the stable free radical TEMPO provides α-(piperidinyloxy) ketones, esters, amides, acids or nitriles in moderate-to-excellent yields. Enolate aggregates influence the outcome of the oxygenation reactions significantly. Competitive reactions have been analyzed and conditions for their minimization are presented. Chemoselective reduction of the products led to either N-O bond cleavage to α-hydroxy carbonyl compounds or reduction of the carbonyl functionality tomonoprotected 1,2-diols or O-protected amino alcohols. The oxygenation of enolates proves to be the most general and effective methodology for the synthesis of O-protected α-oxy carbonyl compounds and nitriles A. The scope and limitations of the electron-transfer-induced radical coupling reaction with TEMPO are presented. The reaction pathways are outlined. Methods for the deprotection to α-hydroxy carbonyl compounds B are provided and discussed. Copyright
- Dinca, Emanuela,Hartmann, Philip,Smrcek, Jakub,Dix, Ina,Jones, Peter G.,Jahn, Ullrich
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supporting information
p. 4461 - 4482
(2012/10/30)
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- Expeditious and novel synthesis of α-hydroxyesters via rhodium-NHC catalyzed arylation of ethyl glyoxalate
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The rhodium-NHC catalyzed arylation reaction of ethyl glyoxalate with aryl and alkyl boronic acids provides an efficient method for the synthesis of α-hydroxyesters. A wide range of α-hydroxyesters (up to 12) were prepared in good to excellent yields. KOtBu was the base of choice, along with tert-amyl alcohol as the solvent. As far as we are aware, this is the first report of this catalytic arylation, using rhodium-NHC catalysts with this specific substrate type.
- Marques, Carolina S.,Burke, Anthony J.
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experimental part
p. 7211 - 7216
(2012/09/05)
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- Asymmetric addition of arylboronic acids to glyoxylate catalyzed by a ruthenium/Me-BIPAM complex
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The enantioselective synthesis of α-hydroxy esters by ruthenium-catalyzed 1,2-addition of arylboronic acids to tert-butyl glyoxylate is described. The use of RuCl2(PPh3)3 with (R,R)-Me-BIPAM gave optically active mandelic acids of up to 99% ee. Addition of a fluoride salt such as potassium fluoride (KF) or caesium fluoride (CsF) was effective for achieving high enantioselectivities. The Royal Society of Chemistry 2012.
- Yamamoto, Yasunori,Shirai, Tomohiko,Miyaura, Norio
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scheme or table
p. 2803 - 2805
(2012/04/23)
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- Highly chemoselective esterification reactions and Boc/THP/TBDMS discriminating deprotections under samarium(III) catalysis
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The usefulness of SmCl3 as an excellent catalyst for chemoselective esterifications and selective removal of acid sensitive protecting groups such as Boc, THP, and TBDMS in the presence of one another is demonstrated through suitable examples.
- Gopinath, Pushparathinam,Nilaya, Surapaneni,Muraleedharan, Kannoth Manheri
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supporting information; experimental part
p. 1932 - 1935
(2011/06/21)
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- Asymmetric aerobic oxidation of α-hydroxy acid derivatives catalyzed by reusable, polystyrene-supported chiral N-salicylidene oxidovanadium tert-leucinates
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The direct immobilization of two different C-5-propargyl ether-modified, chiral N-salicylidene vanadyl(V) tert-leucinates onto 4-azidomethyl-substituted polystyrene by click chemistry was examined. Among the eight different solvents investigated, the resulting polystyrene-supported catalysts promote the asymmetric, aerobic oxidation of α-hydroxy (thio)esters and amides with enantioselectivities of up to 99% ee (selectivity factor up to 41) in chloroform. These polystyrene-supported catalysts can be readily recovered by filtration and reused for at least four consecutive runs without discernible loss of reactivity and enantioselectivity.
- Salunke, Santosh B.,Babu, N.Seshu,Chen, Chien-Tien
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supporting information; experimental part
p. 1234 - 1240
(2011/06/26)
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- 1,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride in combination with triethylamine: An improved catalytic system for hydroacylation/reduction of activated ketones
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A rapid, economic, and high yielding methodology has been developed for hydroacylation/reduction of activated ketones by using 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride as a catalyst in combination with triethylamine. The reaction proceeded at an ambient temperature via generating N-heterocyclic carbene in situ that interacted with the (hetero)aryl aldehyde employed. While the reduction of ketones takes place in MeOH, the hydroacylation process was found to be effective in THF for both electron rich and deficient aldehydes.
- Sreenivasulu,Arun Kumar,Sateesh Reddy,Siva Kumar,Rajender Kumar,Chandrasekhar,Pal, Manojit
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supporting information; experimental part
p. 727 - 732
(2011/03/21)
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- Selective hydrosilylation of ketones catalyzed by in situ -generated iron NHC complexes
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Aryl alkyl-, heteroaryl alkyl- and dialkyl ketones were readily reduced to their corresponding secondary alcohols in high yields, using the commercially available and inexpensive polymeric silane polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by an in situ-generated iron complex, conveniently generated from iron(II) acetate and the commercially available N-heterocyclic carbene (NHC) precursor IPr·HCl.
- Buitrago, Elina,Zani, Lorenzo,Adolfsson, Hans
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experimental part
p. 748 - 752
(2012/01/05)
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- A new dehydrogenase from Clostridium acetobutylicum for asymmetric synthesis: Dynamic reductive kinetic resolution entry into the Taxotere side chain
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An NADP-dependent alcohol dehydrogenase from Clostridium acetobutylicum (CaADH) has been expressed and characterized. CaADH enantioselectively reduces aromatic α-, β- and γ-keto esters to the corresponding d-hydroxy esters and provides a building block for the Taxotere side chain (95% yield, 95% de, 99% ee) by dynamic reductive kinetic resolution (DYRKR).
- Applegate, Gregory A.,Cheloha, Ross W.,Nelson, David L.,Berkowitz, David B.
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supporting information; experimental part
p. 2420 - 2422
(2011/04/15)
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- COMPOUNDS FOR THE REDUCTION OF β-AMYLOID PRODUCTION
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The present disclosure provides a series of compounds of the formula (I) which modulate β-amyloid peptide (β-AP) production and are useful in the treatment of Alzheimer's Disease and other conditions affected by β-amyloid peptide (β-AP) production.
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Page/Page column 108
(2011/02/24)
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- Reduction of aromatic and aliphatic keto esters using sodium borohydride/MeOH at room temperature: a thorough investigation
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Reduction of keto esters is a valuable alternative to produce diols. Sodium borohydride/MeOH system at room temperature and short reaction time efficiently reduced α, β, γ, and δ-keto esters having α-keto esters as the most reactive. The ester functionality was reduced effectively due to the presence of oxo group that somehow facilitates the formation of ring intermediate. As expected, the chemoselective experiments showed that ester functionality was not reduced using this system. This study presents a simple, easy, and benign reduction process of various keto esters to its corresponding diols.
- Kim, Juryoung,De Castro, Kathlia A.,Lim, Minkyung,Rhee, Hakjune
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supporting information; scheme or table
p. 3995 - 4001
(2010/07/05)
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- Zeolite-catalysed conversion of C3 sugars to alkyl lactates
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The direct conversion of C3 sugars (or trioses) to alkyl lactates was achieved using zeolite catalysts. This reaction represents a key step towards the efficient conversion of bio-glycerol or formaldehyde to added-value chemicals such as lactate derivatives. The highest yields and selectivities towards the desired lactate product were obtained with Ultrastable zeolite Y materials having a low Si/Al ratio and a high content of extra-framework aluminium. Correlating the types and amounts of acid sites present in the different zeolites reveals that two acid functions are required to achieve excellent catalysis. Bronsted acid sites catalyse the conversion of trioses to the reaction intermediate pyruvic aldehyde, while Lewis acid sites further assist in the intramolecular rearrangement of the aldehyde into the desired lactate ester product. The presence of strong zeolitic Bronsted acid sites should be avoided as much as possible, since they convert the intermediate pyruvic aldehyde into alkyl acetals instead of lactate esters. A tentative mechanism for the acid catalysis is proposed based on reference reactions and isotopically labelled experiments. Reusability of the USY catalyst is demonstrated for the title reaction.
- Pescarmona, Paolo P.,Janssen, Kris P. F.,Delaet, Chloe,Stroobants, Christophe,Houthoofd, Kristof,Philippaerts, An,De Jonghe, Chantal,Paul, Johan S.,Jacobs, Pierre A.,Sels, Bert F.
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experimental part
p. 1083 - 1089
(2010/08/20)
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- Substituted 1,2,3,4-tetrahydroquinolin-6-yloxypropanes as β3-adrenergic receptor agonists: Design, synthesis, biological evaluation and pharmacophore modeling
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In search of potent β3-adrenergic receptor agonists, a series of novel substituted 1,2,3,4-tetrahydroquinolin-6-yloxypropanes has been synthesized and evaluated for their β3-adrenergic receptor agonistic activity (ranging from -17.73% to 90.64% inhibition at 10 μM) using well established Human SK-N-MC neuroblastoma cells model. Four molecules viz. 11, 15, 22 and 23 showed β3-AR agonistic IC50 value of 0.55, 0.59, 1.18 and 1.76 μM, respectively. These four candidates have been identified as possible leads for further development of β3-adrenergic receptor agonists for obesity and Type-II diabetes pharmacotherapy. The free OH and NH functions are found to be essential for β3-adrenergic receptor agonistic activity. Among the synthesized β3-adrenergic receptor agonists having 1,2,3,4-tetrahydroquinoline scaffold, the N-benzyl group is found to be superior over N-arylsulfonyl group. A putative pharmacophore model has been modeled considering the above four active molecules which distinguishes well between the active and inactive molecules.
- Shakya, Neeraj,Roy, Kuldeep K.,Saxena, Anil K.
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experimental part
p. 830 - 847
(2009/07/25)
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- Addition reaction of arylboronic acids to aldehydes and α,β-unsaturated carbonyl compounds catalyzed by conventional palladium complexes in the presence of chloroform
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Arylboronic acids react with aldehydes and α,β-unsaturated carbonyl compounds in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding addition products in good yields, and chiral benzhydrol was obtained with up to 43% e.e. using (S,S)-bppm as a ligand. General palladium complexes have no catalytic activity without chloroform. Because chloroform is essential for this reaction, these reactions would be promoted by dichloromethylpalladium(II) species.
- Yamamoto, Tetsuya,Iizuka, Michiko,Takenaka, Hiroto,Ohta, Tetsuo,Ito, Yoshihiko
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experimental part
p. 1325 - 1332
(2009/09/28)
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- Stereoselective reduction of carbonyl compounds with actinomycete: Purification and characterization of three α-keto ester reductases from Streptomyces avermitilis
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We achieved the purification of three α-keto ester reductases (Streptomyces avermitilis keto ester reductase, SAKERs-I, -II, and -III) from Streptomyces avermitilis NBRC14893 whole cells. The molecular masses of the native SAKERs-I, -II, and -III were estimated to be 72, 38, and 36 kDa, respectively, by gel filtration chromatography. The subunit molecular masses of SAKERs-I, -II, and -III were also estimated to be 32, 32, and 34 kDa, respectively, by SDS-polyacrylamide gel electrophoresis. The purified SAKERs-II and -III showed a reducing activity for α-keto esters (in particular, for ethyl pyruvate). SAKER-I showed a high reducing activity not only toward the α- and β-keto esters, but also toward α-keto acid. The N-terminal region amino acid sequences of SAKERs-I, -II, and -III were identical to that of a putative oxidoreductase, SAV2750, a putative oxidoreductase, SAV1849, and a putative oxidoreductase, SAV4117, respectively, hypothetical proteins coded on the S. avermitilis genome.
- Ishihara, Kohji,Kato, Chiaki,Yamaguchi, Hitomi,Iwai, Rieko,Yoshida, Momoko,Ikeda, Natsumi,Hamada, Hiroki,Masuoka, Noriyoshi,Nakajima, Nobuyoshi
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body text
p. 3249 - 3257
(2009/04/10)
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