- Mechanistic study of β-substituent effects on the mechanism of ketone reduction by Sml2
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The rate constants for the reduction of 2-butanone, methylacetoacetate, N, N-dimethylacetoacetamide, and a series of 4′- and 2′-substituted acetophenone derivatives by Sml2 were determined in dry THF using stopped-flow absorption decay experiments. Activation parameters for the electron-transfer processes in each series of compounds were determined by a temperature-dependence study over a range of 30 to 50 °C. Two types of reaction pathways are possible for these electron-transfer processes. One proceeds through coordination (Scheme 1) while the other involves chelation (Scheme 2). The results described herein unequivocally show that both coordination and chelation provide highly ordered transition states for the electron-transfer process but the presence of a chelation pathway dramatically increases the rate of the reduction of these substrates by Sml2. The ability of various functional groups to promote a chelated reaction pathway plays a crucial role in determining the rate of the reaction. Among the 2′-substituted acetophenone series, the presence of a fluoro, amino, or methoxy substituent enhances the rate of reduction compared to the 4′-analogues. In particular, the presence of a 2′-fluoro substituent on acetophenone provides a highly ordered transition state and considerably enhances the rate of ketone reduction.
- Prasad, Edamana,Flowers II, Robert A.
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Read Online
- Asymmetric synthesis of secondary benzylic alcohols via arene chromium tricarbonyl complexes
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(Aryl aldehyde)- and (aryl ketone)-chromium tricarbonyl complexes ortho-substituted with the chiral auxiliary O-methyl-N-(α-methylbenzyl)hydroxylamine undergo diastereoselective addition of Grignard reagents and Super-Hydride, respectively, to
- da Costa, M. Rute G.,Curto, M. Jo?o M.,Davies, Stephen G.,Teixeira, Fátima C.,Thomson, James E.
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Read Online
- Facile Access to Triazole-Fused 3,1-Benzoxazines Enabled by Metal-Free Base-Promoted Intramolecular C-O Coupling
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A convenient approach to assemble 1,2,3-triazole-fused 4 H -3,1-benzoxazines has been developed. Diverse alcohol-tethered 5-iodotriazoles, readily accessible by a modified protocol of Cu-catalyzed (3+2)-cycloaddition, were utilized as precursors of the target fused heterocycles. The intramolecular C-O coupling proceeded efficiently under base-mediated transition-metal-free conditions, furnishing cyclization products in yields up to 96%. Suppression of the competing reductive cleavage of the C-I bond was achieved by the use of Na 2CO 3in acetonitrile at 100 °C. This practical and cost-effective procedure features a broad substrate scope and valuable functional group tolerance.
- Tatevosyan, Stepan S.,Kotovshchikov, Yury N.,Latyshev, Gennadij V.,Lukashev, Nikolay V.,Beletskaya, Irina P.
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supporting information
p. 369 - 377
(2021/10/21)
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- In situthermosensitive hybrid mesoporous silica: preparation and the catalytic activities for carbonyl compound reduction
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In this study, free-radical polymerisation inside MCM-41 mesopores was examined to expose a construction route for a temperature-responsive switchable polymer-silica nanohybrid material with well-defined porosity. Herein, we introduced a vinyl monomer (N-isopropyl acrylamide), a cross-linker, and an AIBN initiator into the palladium nanoparticle incorporated MCM-41 pore channels using the wet-impregnation method followed byin situradical polymerisation. The structural properties of the synthesised PNIPAM-PdNP-MCM-41 catalyst were analysed by various sophisticated analytical techniques. The temperature switchable nanohybrid catalyst was used to reduce carbonyl compounds to their corresponding alcohols. The catalyst showed high catalytic efficiency and robustness in an aqueous medium at 25 °C. Moreover, the system's polymer layer remarkably boosted catalytic selectivity and activity for carbonyl compound reduction as compared to other controlled catalysts. The suggested switchable system can be employed as a temperature-controllable heterogeneous catalyst and highlights a substitute technique to counter the methodical insufficiency in switchable supported molecular catalytic system production.
- Ha, Chang-Sik,Mohan, Anandhu,Nagappan, Saravanan,Parambadath, Surendran,Park, Sung Soo,Peter, Jerome,Rout, Lipeeka,Thomas, Anju Maria,Zhang, Wei-Jin
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p. 11730 - 11741
(2021/09/06)
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- Effect of solvent in the hydrogenation of acetophenone catalyzed by Pd/S-DVB
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A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups. The porous structure of the catalyst was characterized by a specific surface area of 94.7 m2g?1. The presence of Pd(ii) and Pd(0) in Pd/S-DVB was evidenced by XPS and TEM. Pd/S-DVB catalyzes the hydrogenation of acetophenone (APh) to 1-phenylethanol (PhE) and ethylbenzene (EtB). The highest conversion of APh was obtained in methanol (MeOH) and in 2-propanol (2-PrOH), while in water it was lower. The conversion of APh correlates well with the hydrogen-bond-acceptance (HBA) capacity of the solvent. However, in all binary mixtures of alcohol and water the APh conversion and the yield of products significantly decreased. The observed inhibiting effect can be explained by the microheterogeneity of these mixtures and the blocking of the catalyst surface restricting access of the substrates to the Pd centers.
- Bereta, Tomasz,Mieczyńska, Ewa,Ronka, Sylwia,Tylus, W?odzimierz,Trzeciak, Anna M.
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p. 5023 - 5028
(2021/03/26)
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- Ruthenium complexes of phosphine-amide based ligands as efficient catalysts for transfer hydrogenation reactions
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This work presents three mononuclear Ru(ii) complexes of tridentate phosphine-carboxamide based ligands providing a NNP coordination environment. The octahedral Ru(ii) ion shows additional coordination with co-ligands; CO, Cl and CH3OH. All three Ru(ii) complexes were thoroughly characterized including their crystal structures. These Ru(ii) complexes were utilized as catalysts for the transfer hydrogenation of assorted carbonyl compounds, including some challenging biologically relevant substrates, using isopropanol as the hydrogen source. The binding studies illustrated the coordination of the isopropoxide ion by replacing a Ru-ligated chloride ion followed by the generation of the Ru-H intermediate that was isolated and characterized and was found to be involved in the catalysis.
- Yadav, Samanta,Vijayan, Paranthaman,Yadav, Sunil,Gupta, Rajeev
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p. 3269 - 3279
(2021/03/16)
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- Highly selective hydrogenation of aromatic ketones to alcohols in water: effect of PdO and ZrO2
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Pd/ZrO2and PdO/ZrO2composites, containing Pd or PdO nanoparticles, were prepared using an original one-step methodology. These nanocomposites catalyze the hydrogenation of acetophenone (AP) at 1 bar and 10 bar of H2in an aqueous solution. Compared to unsupported Pd or PdO nanoparticles, a remarkable increase in their activity was achieved as a result of interaction with zirconia. An unsupported PdO hydrogenated AP mainly to ethylbenzene (EB), while excellent regioselectivity towards 1-phenylethanol (PE) was obtained with PdO/ZrO2and it was preserved during recycling. Similarly, regioselectivity to PE was higher with Pd/ZrO2compared to unsupported Pd NPs. PdO and zirconia resulted in high selectivity to alcohols in the hydrogenation of substituted acetophenones.
- Alsalahi, W.,Trzeciak, A. M.,Tylus, W.
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p. 10386 - 10393
(2021/08/09)
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- Yeast supported gold nanoparticles: an efficient catalyst for the synthesis of commercially important aryl amines
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Candida parapsilosisATCC 7330 supported gold nanoparticles (CpGNP), prepared by a simple and green method can selectively reduce nitroarenes and substituted nitroarenes with different functional groups like halides (-F, -Cl, -Br), olefins, esters and nitriles using sodium borohydride. The product aryl amines which are useful for the preparation of pharmaceuticals, polymers and agrochemicals were obtained in good yields (up to >95%) using CpGNP catalyst under mild conditions. The catalyst showed high recyclability (≥10 cycles) and is a robust free flowing powder, stored and used after eight months without any loss in catalytic activity.
- Krishnan, Saravanan,Patel, Paresh N.,Balasubramanian, Kalpattu K.,Chadha, Anju
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supporting information
p. 1915 - 1923
(2021/02/06)
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- Chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes using carbon-supported palladium catalytic system in water
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Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. Graphic abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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p. 3289 - 3312
(2021/05/11)
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- N-Heterocyclic Carbene (NHC)-Stabilized Ru0 Nanoparticles: In Situ Generation of an Efficient Transfer Hydrogenation Catalyst
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Tethered and untethered ruthenium half-sandwich complexes were synthesized and characterized spectroscopically. X-ray crystallographic analysis of three untethered and two tethered Ru N-heterocyclic carbene (NHC) complexes were also carried out. These RuNHC complexes catalyze transfer hydrogenation of aromatic ketones in 2-propanol under reflux, optimally in the presence of (25 mol %) KOH. Under these conditions, the formation of 2–3 nm-sized Ru0 nanoparticles was detected by TEM measurements. A solid-state NMR investigation of the nanoparticles suggested that the NHC ligands were bound to the surface of the Ru nanoparticles (NPs). This base-promoted route to NHC-stabilized ruthenium nanoparticles directly from arene-tethered ruthenium–NHC complexes and from untethered ruthenium–NHC complexes is more convenient than previously known routes to NHC-stabilized Ru nanocatalysts. Similar catalytically active RuNPs were also generated from the reaction of a mixture of [RuCl2(p-cymene)]2 and the NHC precursor with KOH in isopropanol under reflux. The transfer hydrogenation catalyzed by these NHC-stabilized RuNPs possess a high turnover number. The catalytic efficiency was significantly reduced if nanoparticles were exposed to air or allowed to aggregate and precipitate by cooling the reaction mixtures during the reaction.
- Kathuria, Lakshay,Din Reshi, Noor U.,Samuelson, Ashoka G.
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supporting information
p. 7622 - 7630
(2020/05/29)
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- Cooperative Mn(i)-complex catalyzed transfer hydrogenation of ketones and imines
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The synthesis and reactivity of Mn(i) complexes bearing bifunctional ligands comprising both the amine N-H and benzimidazole fragments are reported. Among the various ligands, the N-((1H-benzimidazol-2-yl)methyl)aniline ligand containing Mn(i) complex presented higher reactivity in the transfer hydrogenation (TH) of ketones in 2-propanol. Experimentally, it was established that both the benzimidazole and amine N-H proton played a vital role in the enhancement of the catalytic activity. Utilizing this system a wide range of aldehydes and ketones were reduced efficiently. Notably, the TH of several imines, as well as chemoselective reduction of unsaturated ketones, was achieved in the presence of this catalyst. DFT calculations were carried out to understand the plausible reaction mechanism which disclosed that the transfer hydrogenation reaction followed a concerted outer-sphere mechanism.
- Ganguli, Kasturi,Shee, Sujan,Panja, Dibyajyoti,Kundu, Sabuj
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p. 7358 - 7366
(2019/06/06)
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- Structural, kinetics and mechanistic studies of transfer hydrogenation of ketones catalyzed by chiral (pyridyl)imine nickel(ii) complexes
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The chiral synthons (S-)-1-phenyl-N-(pyridine-2-yl)ethylidine)ethanamine (L1), (R-)-1phenyl-N-(pyridine-2-yl)ethylidine))ethanamine (L2) (S)-1-phenyl-N-(pyridine-2-yl methylene) ethanamine (L3), and (R)-1-phenyl-N-(pyridine-2-yl methylene) ethanamine (L4) were synthesized in good yields. Treatments of L1-L4 with NiBr2(DME) and NiCl2 precursor afforded dinuclear complexes [Ni2(L1)4-μ-Br2]NiBr4 (Ni1), [Ni2(L2)4-μ-Br2]NiBr4 (Ni2), [Ni2(L3)4-μBr2]Br2 (Ni3), [Ni2(L4)4-μ-Br2]NiBr4 (Ni4) and [Ni(L4)2Cl2] (Ni5). The identities of the compounds were established using NMR, FT-IR and EPR spectroscopy, mass spectrometry, magnetic moments, elemental analysis and single crystal X-ray crystallography. The dinuclear dibromide nickel complexes dissociate into mononuclear species in the presence of strongly coordinating solvents. Compounds Ni1-Ni5 displayed moderate catalytic activities in the asymmetric transfer hydrogenation (ATH) of ketones, but with low enantiomeric excess (ee%). Both mercury and substoichiometric poisoning tests pointed to the homogeneous nature of the active species with the partial formation of catalytically active Ni(0) nanoparticles. Low resolution mass spectrometry analyses of the intermediates supported a dihydride mechanistic pathway for the transfer of hydrogenation reactions.
- Kumah, Robert T.,Tsaulwayo, Nokwanda,Xulu, Bheki A.,Ojwach, Stephen O.
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supporting information
p. 13630 - 13640
(2019/09/30)
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- Magnetically Recyclable Metal–Organic Framework@Fe3O4 Composite-Catalyzed Facile Reduction of Nitroarene Compounds in Aqueous Medium
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A kind of Metal–organic framework (MOF) composite namely Cu-BTC@Fe3O4 (BTC?=?1,3,5-benzenetricarboxylate) was prepared and showed good catalytic activity toward the reduction of nitroarenes. This reaction proceeded smoothly under mild reaction conditions in aqueous medium using sodium borohydride as the reduction agent, affording the corresponding anilines in good to excellent yields. In addition, the catalyst could be easily recovered with an external permanent magnet and be reused for successive six runs with slight decrease in its activity.
- Yang, Sen,Zhang, Zhi-Hui,Chen, Qun,He, Ming-Yang,Wang, Liang
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- Metal free carboamination of internal alkynes - An easy access to polysubstituted quinolines
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A metal free carboamination of unactivated alkynes towards highly substituted quinolines was realized in the presence of a synergistic Br?nsted acid catalyst system. Supported by mechanistic probes, the reaction proceeds via a highly reactive vinyl cation in a C-C bond formation - Schmidt reaction sequence. The irreversible extrusion of N2, as a powerful driving force, allows for a general conversion of poorly nucleophilic aliphatic alkynes.
- Stopka,Niggemann
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supporting information
p. 5761 - 5764
(2016/05/19)
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- Sunlight-Driven Forging of Amide/Ester Bonds from Three Independent Components: An Approach to Carbamates
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A photoredox catalytic route to carbamates enabled by visible irradiation (or simply sunlight) has been developed. This process leads to a novel approach to the construction of heterocyclic rings wherein the amide or ester motifs of carbamates were assembled from three isolated components. Large-scale experiments were realized by employing continuous flow techniques, and reuse of photocatalyst demonstrated the green and sustainable aspects of this method.
- Zhao, Yating,Huang, Binbin,Yang, Chao,Chen, Qingqing,Xia, Wujiong
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supporting information
p. 5572 - 5575
(2016/11/17)
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- Metal- and Protection-Free [4 + 2] Cycloadditions of Alkynes with Azadienes: Assembly of Functionalized Quinolines
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A base promoted, protection-free, and regioselective synthesis of highly functionalized quinolines via [4 + 2] cycloaddition of azadienes (generated in situ from o-aminobenzyl alcohol) with internal alkynes has been discovered. The reaction tolerates a wide variety of functional groups which has been successfully extended with diynes, (2-aminopyridin-3-yl)methanol, and 1,4-bis(phenylethynyl)benzene to afford (Z)-phenyl-2-styrylquinolines, phenylnaphthyridine, and alkyne-substituted quinolines, respectively. The proposed mechanism and significant role of the solvent were well supported by isolating the azadiene intermediate and deuterium-labeling studies.
- Saunthwal, Rakesh K.,Patel, Monika,Verma, Akhilesh K.
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supporting information
p. 2200 - 2203
(2016/06/01)
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- Cheap and environmentally sustainable stereoselective arylketones reduction by Lactobacillus reuteri whole cells
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Various Lactobacillus reuteri strains were investigated as whole cell catalysts for the bioreduction of acetophenone into optically active (R)-1-phenylethanol. L. reuteri DSM 20016 strain gave an almost complete substrate conversion, in a short reaction time and enantiomeric excess up to 99%. The acetophenone bioreduction was used as a model reaction to optimize temperature and reducing equivalent source (glucose, lactose, cheese way and lignocellulosic hydrolysates) to accomplish the biotransformation. The reduction of acetophenones into optically active (R)-1-arylethanols was also exploited to study L. reuteri DSM 20016 substrate specificity. In most of the cases, optically active (R)-1-arylethanols have been obtained with both excellent chemical and optical yields and with (R)-enantiopreference, through a cheap, simple and efficient process.
- Perna,Ricci,Scilimati,Mena,Pisano,Palmieri,Agrimi,Vitale
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- An efficient iron-promoted synthesis of 6H-indolo[2,3- b] quinolines and neocryptolepine derivatives
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A facile and practical method for the preparation of 6H-indolo[2,3-b]quinolines and neocryptolepines was developed under the promotion of the easily available ferric trichloride, affording the desired products with moderate to good yields.
- Yan, Zicong,Wan, Changfeng,Wan, Jianyong,Wang, Zhiyong
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supporting information
p. 4405 - 4408
(2016/06/06)
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- Regioselective Synthesis of C-3-Functionalized Quinolines via Hetero-Diels-Alder Cycloaddition of Azadienes with Terminal Alkynes
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A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The -NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.
- Saunthwal, Rakesh K.,Patel, Monika,Verma, Akhilesh K.
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p. 6563 - 6572
(2016/08/16)
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- Iodine-mediated intramolecular amination of ketones: The synthesis of 2-acylindoles and 2-acylindolines by tuning N-protecting groups
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A general method for constructing both 2-acylindoles and 2-acylindolines via I2-mediated intramolecular C-N bond formation is presented, and the selective formation of either 2-acylindoles or 2-acylindolines just depends on the nitrogen protecting groups used in the same substrate skeletons. The Royal Society of Chemistry.
- Gao, Wen-Chao,Jiang, Shan,Wang, Ruo-Lin,Zhang, Chi
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supporting information
p. 4890 - 4892
(2013/07/05)
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- Asymmetric reduction of acetophenone derivatives by Lens culinaris
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The enzymatic reduction of acetophenone derivatives has been evaluated using whole cells from the edible plant lentil (Lens culinaris) as biocatalyst to afford chiral (R) and (S)-alcohols in enantiomeric excess 68-99%. Acetophenone was selected as the model substrate for enantioselective bioreduction. The reaction was performed under a range of conditions in order to optimize the bioreduction procedure with respect to reaction time, media and optimal mass of lentil. With substituted (fluorine, chlorine, bromine, methyl, hydroxyl, methoxy, amino and nitro groups) acetophenones, electronic and steric influences on the course of the reaction were observed.
- Ferreira, Daniele Alves,Da Costa Assun??o, Jo?o Carlos,De Lemos, Telma Leda Gomes,Monte, Francisco José Queiroz
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p. 469 - 475
(2013/02/23)
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- Convenient and scalable process for the preparation of indole via raney nickel-catalyzed hydrogenation and ring closure
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An efficient and practical method for the synthesis of indole as a key starting material for many useful chemicals is described. Using 2-nitrotoluene as starting material, hydroxymethylation with formaldehyde under alkaline conditions gave 2-(2-nitrophenyl) ethanol on a large scale. Raney Ni catalyst was used for both reduction of the nitro group as well as for the indole formation. The overall yield was 78% from 2-nitrotoluene. Copyright
- Guo, Xianghai,Peng, Zhiliang,Jiang, Shende,Shen, Jiaxiang
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p. 2044 - 2052
(2011/08/03)
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- Candida tenuis xylose reductase catalysed reduction of acetophenones: The effect of ring-substituents on catalytic efficiency
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The catalytic efficiencies of Candida tenuis xylose reductase catalysed reductions of mono-substituted acetophenones are in reasonable correlation with the σ-Hammett coefficients of the substituted phenyl groups. Variations of the substrate transformation rates are hence mainly caused by mesomeric and inductive effects of the substituents, while differences in substrate binding have a secondary relevance. Some substrate 1H NMR chemical shifts and carbonyl IR absorption bands are in reasonable accordance with the catalytic activities and allow the estimation of the transformation rates with good accuracy. The resulting substituted (S)-1-phenyl ethanols are generated in very high enantiomeric excess.
- Vogl, Michael,Kratzer, Regina,Nidetzky, Bernd,Brecker, Lothar
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experimental part
p. 5863 - 5870
(2011/09/30)
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- Magnetically recoverable supported ruthenium catalyst for hydrogenation of alkynes and transfer hydrogenation of carbonyl compounds
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A ruthenium (Ru) catalyst supported on magnetic nanoparticles (NiFe2O4) has been successfully synthesized and used for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The catalyst shows excellent selectivity toward the desired products with very high yield even after five repeated uses.
- Baruwati, Babita,Polshettiwar, Vivek,Varma, Rajender S.
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scheme or table
p. 1215 - 1218
(2009/05/27)
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- An enantiopure galactose oxidase model: synthesis of chiral amino alcohols through oxidative kinetic resolution catalyzed by a chiral copper complex
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An enantiopure galactose oxidase (GO) enzyme model has been synthesized from readily available (R)-BINAM and Cu(OTf)2, and the enantiopure GO model has been effectively used in situ as an efficient chiral catalyst for the synthesis of chiral amino alcohols through oxidative kinetic resolution (OKR), where molecular oxygen is used as the sole oxidant. Under the proposed catalytic conditions, both ortho- and para-substituted amino alcohols were resolved with good to excellent enantiomeric excesses through oxidative kinetic resolution.
- Mannam, Sreedevi,Sekar, Govindasamy
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experimental part
p. 497 - 502
(2009/07/18)
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- A flexible synthesis of 2,3-disubstituted indoles from aminobenzyl phosphonium salts. A direct synthesis of rutaecarpine
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(Chemical Equation Presented) The reaction of substituted (2-aminobenzyl)triphenylphosphonium bromides with aromatic aldehydes or α,β-unsaturated aldehydes constitutes a new synthesis of 2,3-disubstitued indoles in high yields. The adduct from 4-oxo-3,4- dihydroquinazoline-2-carbaldehyde was an advanced intermediate in the synthesis of several rutaecarpines.
- Kraus, George A.,Guo, Haitao
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scheme or table
p. 5337 - 5341
(2009/11/30)
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- Nanoparticle-supported and magnetically recoverable nickel catalyst: A robust and economic hydrogenation and transfer hydrogenation protocol
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A magnetic nanoparticle-supported leach-proof Ni catalyst was readily prepared from inexpensive starting materials which catalyzes various hydrogenation and transfer hydrogenation reactions; high catalytic activity and ease of recovery using an external magnetic field are additional eco-friendly attributes of this catalytic system.
- Polshettiwar, Vivek,Baruwati, Babita,Varma, Rajender S.
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experimental part
p. 127 - 131
(2010/04/22)
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- Cyclic guanidines as dual 5-HT5A/5-HT7 receptor ligands: Optimising brain penetration
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The optimisation of molecular properties within a series of 2-amino dihydroquinazoline 5-HT5A/5-HT7 receptor ligands resulted in a significantly improved brain-to-plasma ratio, enhancing the pharmacological utility of these compounds
- Peters, Jens-Uwe,Luebbers, Thomas,Alanine, Alexander,Kolczewski, Sabine,Blasco, Francesca,Steward, Lucinda
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p. 262 - 266
(2008/09/17)
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- Cascade synthesis of 3-quinolinecarboxylic ester via benzylation/ propargylation-cyclization
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(Chemical Equation Presented) Reactions of 2-amino-aryl alcohols with β-ketoesters catalyzed by a catalytic amout of FeCl3 via tandem benzylation-cyclization produce the corresponding 3-quinolinecarboxylic esters in good to high yields. Extending this methodology to propargylation- cyclization, 2-nitrophenyl propargyl alcohols with β-ketoesters catalyzed by FeCl3 and SnCl2 also produce the 4-alkyne-3- quinolinecarboxylic esters. The mechanistic details of this benzylation/ propargylation and cyclization cascade process are also discussed.
- Fan, Jinmin,Wan, Changfeng,Sun, Gaojun,Wang, Zhiyong
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supporting information; experimental part
p. 8608 - 8611
(2009/04/04)
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- Synthesis of the antitumoural agent batracylin and related isoindolo[1,2-b]quinazolin-12(10H)-ones
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The synthesis of batracylin and related isoindolo[1,2-b]quinazolin-12-ones from easily accessible o-acylanilines is reported. The preparation of these tetracyclic compounds through a Mitsunobu reaction followed by spontaneous cyclodehydration shows the ability of this methodology to afford good yields of a wide variety of diversely 7, 8, 9, 10-substituted isoindoloquinazolinones in two steps.
- Martínez-Viturro, Carlos M.,Domínguez, Domingo
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p. 1023 - 1026
(2008/02/04)
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- NaBH4/charcoal: A new synthetic method for mild and convenient reduction of nitroarenes
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NaBH4 in the presence of charcoal (0.4-0.8 g) reduces varieties of nitroarenes to their corresponding amines. Reduction reactions were carried out in a mixture of H2O-THF (1:0.5 mL) at 50-60°C with high to excellent yields of products. Copyright Taylor & Francis Group, LLC.
- Zeynizadeh, Behzad,Setamdideh, Davood
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p. 2699 - 2704
(2007/10/03)
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- Novel approach to isoindolo[2,1-a]quinolines
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An N-acyliminium ion approach towards the synthesis of isoindolo [2,1- a]quinolines by an intramolecular process is described.
- Pigeon, Pascal,Decroix, Bernard
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p. 2507 - 2516
(2007/10/03)
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- A molybdenum-catalyzed oxidative system forming oxazines (hetero-Diels-Alder adducts) from primary aromatic amines, hydrogen peroxide, and conjugated dienes
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The development of a new molybdenum-catalyzed procedure for the formation of oxazines-hetero-Diels-Alder adducts - from primary aromatic amines, hydrogen peroxide, and conjugated dienes is presented. The method is based on a molybdenum-peroxo complex, which in the presence of hydrogen peroxide as the terminal oxidant selectively catalyzes the oxidation of primary aromatic amines to the corresponding dienophilic nitroso compounds. The molybdenum-peroxo catalyst is under the present reaction conditions not reactive toward conjugated dienes and substituents attached to the aromatic nuclei of the primary aromatic amines. Several oxazines are synthezised following this new procedure using primary aromatic amines having either electron-withdrawing or electron-donating substituents and 1,3-cyclohexadiene as the standard diene. The scope of the new procedure is also demonstrated by the preparation of several oxazines using different alkyland phenyl-substituted conjugated dienes and 4-chloroaniline as precursor for the dienophile. Moderate diastereomeric excesses are found when the reaction is carried out with 1-(2-aminophenyl)-ethanol and 1,3-cyclohexadiene or (E)-1-phenyl-1,3-butadiene. The stereochemical and electronic factors governing the reaction course are briefly discussed.
- Moller, Eval Rud,Jorgensen, Karl Anker
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p. 5770 - 5778
(2007/10/03)
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- Compounds substituted quinoline derivatives
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Substituted 4-aminoquinazoline derivatives which are inhibitors of gastric acid secretion. A compound of the invention are the salts of strong acids of 3-butyryl-4-(2-methylphenylamino)-8-(hydroxymethyl)quinoline.
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- Substituted 4-aminoquinoline derivatives as gastric acid secretion inhibitors
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Substituted 4-aminoquinazoline derivatives of the formula: STR1 in which R1 is hydrogen, C1-6 alkyl, C1-6 alkoxy, C1-6 alkoxyC1-6 alkyl, C3-6 cycloalkyl, C3-6 cycloalkylC1-6 alkyl, phenylC1-6 alkyl, the phenyl group being optionally substituted; R2 is hydrogen, C1-6 alkyl, C1-6 alkoxy, amino, C1-6 alkylthio, halogen, cyano, hydroxy, carbamoyl, carboxy, C1-6 alkanoyl or trifluoromethyl; m is 1 to 3; p is 0 to 4; R3 is COR4 ; R4 is hydroxy, C1-6 alkoxy, or NR5 R6 ; R5 and R6 are each hydrogen or C1-6 alkyl or together with the nitrogen atom to which they are attached form a heterocyclic ring; and R7 is hydrogen, C1-6 alkoxy or C1-6 alkyl; or a salt thereof.
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- SELECTIVE REDUCTION OF KETONES WITH SODIUMBOROHYDRIDE-ACETIC ACID
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Aliphatic ketones, and aromatic ketones having o-hydroxy or o-amino substituents are reduced rapidly to the alcohols by NaBH4 and acetic acid; other types of ketones react much more slowly.
- Nieminen, Tuula, E. A.,Hase, Tapio A.
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p. 4725 - 4728
(2007/10/02)
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- Two New Oxindole Syntheses
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Two oxindole syntheses are described, both starting from ketones, in which the carbonyl carbon becomes C-3 of the oxindole.The first route uses o-lithioformanilide followed by attack with cyanide ion and hydrolysis.The second uses a pinacol-type rearragement (or the γ-silyl alcohol variation) to create the quaternary centre, and involves an intramolecular displacement of fluoride ion from an unactivated benzene ring by an amide nitrogen to complete the lactam ring.The two routes are stereochemically complementary, giving different spiro-oxindoles from norbornanone.
- Fleming, Ian,Loreto, Maria Antonietta,Wallace, Ian H.M.,Michael, Joseph P.
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p. 349 - 360
(2007/10/02)
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