- Solid-Liquid Phase Transfer Catalysis I. Benzylation of Malononitrile
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Benzylation of malononitrile has been carried out under solid-liquid phase-transfer catalysis conditions without solvent.The influence of different variables, such as type of base, addition of alumina, molar ratio of phase-transfer agent, temperature, tim
- Diez-Barra, E.,Hoz, A. de la,Moreno, A.,Sanchez-Verdu, P.
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- Copper-catalyzed enantioselective intramolecular aryl C-N coupling: Synthesis of enantioenriched 2-Oxo-1,2,3,4-tetrahydroquinoline-3-carboxamides via an asymmetric desymmetrization strategy
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The differentiation of two nucleophilic amide groups in malonamides through a copper-catalyzed enantioselective intramolecular aryl C-N coupling reaction is demonstrated based on an asymmetric desymmetrization strategy. Such a method afforded enantioenriched 2-oxo-1,2,3,4-tetrahydroquinoline-3-carboxamides in high yields and moderate to good enantioselectivity.
- He, Nian,Huo, Yanping,Liu, Jianguang,Huang, Yusha,Zhang, Shasha,Cai, Qian
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- New aspects of Knoevenagel condensation and Michael addition reactions on alkaline carbonates
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The Knoevenagel condensation of malononitrile with benzaldehyde on K2CO3, Rb2CO3 and Cs2CO3 gave the condensation product benzylidenemalononitrile but the reaction proceeded to the hydrogen
- Aramendia, Maria A.,Borau, Victoriano,Jimenez, Cesar,Marinas, Jose M.,Romero, Francisco J.
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- Synthesis and biocatalytic ene-reduction of Knoevenagel condensation compounds by the marine-derived fungus Penicillium citrinum CBMAI 1186
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The chemoselective bioreduction of α,β-unsaturated compounds is an important synthetic tool that can have applications in the synthesis of many fine chemicals and pharmaceutical molecules. The synthesis of aromatic malononitrile derivatives through Knoevenagel condensation by microwave radiation under green chemistry conditions using methanol like solvent, free base and free catalyst is here reported. In addiction the biocatalytic reduction of the C–C double bond of aromatic malononitrile derivatives by whole cells of the marine-derived fungal Penicillium citrinum CBMAI 1186 was also tested. The products catalyzed by the fungus ene-reductase were obtained in very good yields (up to >98%).
- Jimenez, David E.Q.,Ferreira, Irlon M.,Birolli, Willian G.,Fonseca, Luis P.,Porto, André L.M.
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- A novel bifunctional Pd-ZIF-8/rGO catalyst with spatially separated active sites for the tandem Knoevenagel condensation-reduction reaction
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A novel bifunctional catalyst with spatially separated active sites was prepared by the immobilization of Pd nanoparticles (NPs) via covalent interaction and coordination of a zeolitic imidazolate framework (ZIF-8) on the surface of graphene oxide (GO), respectively, which was used as an efficient catalyst for the Knoevenagel condensation-reduction tandem reaction. The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated that Pd and ZIF-8 were successfully immobilized on the surface of GO, and the GO was reduced to reduced graphene oxide (rGO) using NaBH4 as the reductant in the preparation of Pd-ZIF-8/rGO. The textural properties and morphology of Pd-ZIF-8/rGO were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Pd-ZIF-8/rGO shows excellent catalytic performance in the tandem reaction with 100% benzaldehyde conversion and 98.3% selectivity to benzylmalononitrile. The excellent catalytic performance of Pd-ZIF-8/rGO in the tandem reaction is due to the high catalytic activities of spatially separated Pd NPs and ZIF-8 active sites and concentrated reactants on the surface of Pd-ZIF-8/rGO due to the π-π interaction between rGO and the reactants. The anchoring and stabilization effects of oxygenated groups of GO inhibit the aggregation and leakage of active sites, leading to good catalytic recyclability with almost unchanged catalytic activity for more than eight cycles in the tandem reaction.
- Wang, Hefang,Wang, Yansu,Jia, Aizhong,Wang, Cunyue,Wu, Luming,Yang, Yongfang,Wang, Yanji
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- Catalyst-Free [3 + 3] Annulation/Oxidation of Cyclic Amidines with Activated Olefins: When the Substrate Olefin Is Also an Oxidant
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Herein we describe a catalyst-free regioselective [3 + 3] annulation/oxidation reaction of cyclic amidines such as DBU (1,8-diazabicyclo(5.4.0)undec-7-ene) and DBN (1,5-diazabicyclo(4.3.0)non-5-ene) with activated olefins, i.e., 2-arylidenemalononitriles and 2-cyano-3-aryl acrylates, to afford tricyclic 2-pyridones and pyridin-2(1H)-imines, respectively. The mechanism has been proposed based on DFT calculations. In the reaction, the cyclic amidines serve as C,N-bisnucleophiles for the cyclization, while the olefins play a dual role by acting as both reactants and oxidants.
- Han, Wendan,Li, Yuanhang,Raveendra Babu, Kaki,Li, Jing,Tang, Yuhai,Wu, Yong,Xu, Silong
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- Ionization of carbon acids in liquid ammonia
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The acidities of various carbon acids in liquid ammonia (LNH3) at room temperature were determined by NMR and rates of D-exchange. There is a reasonable linear correlation of the pKas in LNH3 with those in water and DMSO of slope 0.7 and 0.8, respectively. Carbon acids with an aqueous pKa of less than 12 are fully ionized in liquid ammonia. Nucleophilic substitution of benzyl chloride by carbanions in liquid ammonia generates a Bronsted βnuc = 0.38.
- Ji, Pengju,Powles, Nicholas T.,Atherton, John H.,Page, Michael I.
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- Sodium borohydride as the only reagent for the efficient reductive alkylation of malononitrile with ketones and aldehydes
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An efficient and convenient method for the synthesis of primary and secondary monosubstituted malononitriles has been developed. In this method, sodium borohydride in isopropanol has a catalytic effect on the initial condensation between malononitrile and
- Dunham, Jason C.,Richardson, Adam D.,Sammelson, Robert E.
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- Stereoselective desymmetrizations of dinitriles to synthesize lactones
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Nitriles are important organic functional groups, allowing for installation of nitrogen in organic synthesis. The Pinner reaction transforms nitriles into esters via the imidate group, but in general has previously necessitated harsh acid conditions. This
- Baber, Tylisha M.,Bain, Schuyler A.,Caleb Lykins, T.,Frost, Joshua A.,Kelley, Amber M.,Michishita, Emiri,Petersen, Kimberly S.,Youngblood, Kala C.
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supporting information
(2021/12/17)
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- Selective Synthesis of β-Ketonitriles via Catalytic Carbopalladation of Dinitriles
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A practical, convenient, and highly selective method of synthesizing β-ketonitriles from the Pd-catalyzed addition of organoboron reagents to dinitriles has been developed. This method provides excellent functional-group tolerance, a broad scope of substrates, and the convenience of using commercially available substrates. The method is expected to show further utility in future synthetic procedures.
- Zeng, Ge,Liu, Jichao,Shao, Yinlin,Zhang, Fangjun,Chen, Zhongyan,Lv, Ningning,Chen, Jiuxi,Li, Renhao
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p. 861 - 867
(2021/01/09)
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- Photoredox-Catalyzed Simultaneous Olefin Hydrogenation and Alcohol Oxidation over Crystalline Porous Polymeric Carbon Nitride
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Booming of photocatalytic water splitting technology (PWST) opens a new avenue for the sustainable synthesis of high-value-added hydrogenated and oxidized fine chemicals, in which the design of efficient semiconductors for the in-situ and synergistic utilization of photogenerated redox centers are key roles. Herein, a porous polymeric carbon nitride (PPCN) with a crystalline backbone was constructed for visible light-induced photocatalytic hydrogen generation by photoexcited electrons, followed by in-situ utilization for olefin hydrogenation. Simultaneously, various alcohols were selectively transformed to valuable aldehydes or ketones by photoexcited holes. The porosity of PPCN provided it with a large surface area and a short transfer path for photogenerated carriers from the bulk to the surface, and the crystalline structure facilitated photogenerated charge transfer and separation, thus enhancing the overall photocatalytic performance. High reactivity and selectivity, good functionality tolerance, and broad reaction scope were achieved by this concerted photocatalysis system. The results contribute to the development of highly efficient semiconductor photocatalysts and synergistic redox reaction systems based on PWST for high-value-added fine chemical production.
- Qiu, Chuntian,Sun, Yangyang,Xu, Yangsen,Zhang, Bing,Zhang, Xu,Yu, Lei,Su, Chenliang
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p. 3344 - 3350
(2021/07/26)
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- Direct Cyclopropanation of α-Cyano β-Aryl Alkanes by Light-Mediated Single Electron Transfer Between Donor–Acceptor Pairs
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Cyclopropanes are traditionally prepared by the formal [2+1] addition of carbene or radical based C1 units to alkenes. In contrast, the one-pot intermolecular cyclopropanation of alkanes by redox active C1 units has remained unrealised. Herein, we achieve
- Li, Jing,Lear, Martin J.,Hayashi, Yujiro
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supporting information
p. 5901 - 5905
(2021/03/09)
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- Enantioselective Assembly of Cycloenones with a Nitrile-Containing All-Carbon Quaternary Center from Malononitriles Enabled by Ni Catalysis
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Chiral nitriles are valuable molecules in modern organic synthesis and drug discovery. Selectively differentiating the two nitrile groups of widely available malononitrile derivatives is a straightforward yet underdeveloped route to construct enantioenriched nitriles. Here we report an enantioselective nickel-catalyzed desymmetrization of malononitriles for the generation of nitrile-containing all-carbon quaternary stereocenters. This protocol involves a nickel-catalyzed addition of aryl boronic acids to alkynes, followed by a selective nitrile insertion, providing unprecedented access to enantioenriched 5-7-membered α-cyano-cycloenones with a fully substituted olefin from a broad range of substrates. The synthetic utility of these nitrile products is demonstrated by gram-scale synthesis and conversion to several useful functional groups.
- Lu, Zhiwu,Hu, Xu-Dong,Zhang, Hui,Zhang, Xiao-Wen,Cai, Jinhui,Usman, Muhammad,Cong, Hengjiang,Liu, Wen-Bo
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supporting information
p. 7328 - 7333
(2020/08/19)
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- Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
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Reversible catalytic reactions operate under thermodynamic control, and thus, establishing a selective catalytic system poses a considerable challenge. Herein, we report a reversible transfer hydrocyanation protocol that exhibits high selectivity for the thermodynamically less favorable branched isomer. Selectivity is achieved by exploiting the lower barrier for C-CN oxidative addition and reductive elimination at benzylic positions in the absence of a cocatalytic Lewis acid. Through the design of a novel type of HCN donor, a practical, branched-selective, HCN-free transfer hydrocyanation was realized. The synthetically useful resolution of a mixture of branched and linear nitrile isomers was also demonstrated to underline the value of reversible and selective transfer reactions. In a broader context, this work demonstrates that high kinetic selectivity can be achieved in reversible transfer reactions, thus opening new horizons for their synthetic applications.
- Bhawal, Benjamin N.,Ehinger, Christian,Morandi, Bill,Reisenbauer, Julia C.
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p. 10914 - 10920
(2020/07/13)
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- Titanium(III)-Catalyzed Reductive Decyanation of Geminal Dinitriles by a Non-Free-Radical Mechanism
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A titanium-catalyzed mono-decyanation of geminal dinitriles is reported. The reaction proceeds under mild conditions, tolerates numerous functional groups, and can be applied to quaternary malononitriles. A corresponding desulfonylation is demonstrated as well. Mechanistic experiments support a catalyst-controlled cleavage without the formation of free radicals, which is in sharp contrast to traditional stoichiometric radical decyanations. The involvement of two TiIII species in the C?C cleavage is proposed, and the beneficial role of added ZnCl2 and 2,4,6-collidine hydrochloride is investigated.
- Weweler, Jens,Younas, Sara L.,Streuff, Jan
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supporting information
p. 17700 - 17703
(2019/11/13)
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- Mn-Catalyzed Electrochemical Chloroalkylation of Alkenes
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The heterodifunctionalization of alkenes is an efficient method for synthesizing highly functionalized organic molecules. In this report, we describe the use of anodically coupled electrolysis for the catalytic chloroalkylation of alkenes - a reaction that constructs vicinal C-C and C-Cl bonds in a single synthetic operation - from malononitriles or cyanoacetates and NaCl. Knowledge of the persistent radical effect guided the reaction design and development. A series of controlled experiments, including divided-cell electrolysis that compartmentalized the anodic and cathodic events, allowed us to identify the key radical intermediates and the pathway to their electrocatalytic formation. Cyclic voltammetry data further support the proposed mechanism entailing the parallel, Mn-mediated generation of two radical intermediates in an anodically coupled electrolysis followed by their selective addition to the alkene.
- Fu, Niankai,Shen, Yifan,Allen, Anthony R.,Song, Lu,Ozaki, Atsushi,Lin, Song
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p. 746 - 754
(2019/01/11)
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- Preparation of O-Protected Cyanohydrins by Aerobic Oxidation of α-Substituted Malononitriles in the Presence of Diarylphosphine Oxides
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A mild, reagent-cyanide-free, and efficient synthesis of O-phosphinoyl-protected cyanohydrins from readily available α-substituted malononitriles was realized using diarylphosphine oxides in the presence of O2. Mechanistic studies indicated that in addition to the initial aerobic oxidation of the malononitrile derivative notable features of this process include the formation of a tetrahedral intermediate and a subsequent intramolecular rearrangement. The phosphinoyl-protecting group can be removed by alcoholysis or by reduction with DIBAL-H.
- Zhang, Dapeng,Lian, Mingming,Liu, Jia,Tang, Shukun,Liu, Guangzhi,Ma, Cunfei,Meng, Qingwei,Peng, Haisheng,Zhu, Daling
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p. 2597 - 2601
(2019/04/17)
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- Room Temperature, Reductive Alkylation of Activated Methylene Compounds: Carbon-Carbon Bond Formation Driven by the Rhodium-Catalyzed Water-Gas Shift Reaction
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The rhodium-catalyzed water-gas shift reaction has been demonstrated to drive the reductive alkylation of several classes of activated methylene compounds at room temperature. Under catalysis by rhodium trichloride (2-3 mol %), carbon monoxide (10 bar), water (2-50 equiv), and triethylamine (2.5-7 equiv), the scope has been successfully expanded to cover a wide range of alkylating agents, including aliphatic and aromatic aldehydes, as well as cyclic ketones, in moderate to high yields. This method is comparable to, and for certain aspects, surpasses the established reductive alkylation protocols.
- Denmark, Scott E.,Ibrahim, Malek Y. S.,Ambrosi, Andrea
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p. 613 - 630
(2017/06/05)
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- Metal–Organic-Framework-Derived Carbons: Applications as Solid-Base Catalyst and Support for Pd Nanoparticles in Tandem Catalysis
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The facile pyrolysis of a bipyridyl metal-organic framework, MOF-253, produces N-doped porous carbons (Cz-MOF-253), which exhibit excellent catalytic activity in the Knoevenagel condensation reaction and outperform other nitrogen-containing MOF-derived ca
- Li, Xinle,Zhang, Biying,Fang, Yuhui,Sun, Weijun,Qi, Zhiyuan,Pei, Yuchen,Qi, Shuyan,Yuan, Pengyu,Luan, Xuechen,Goh, Tian Wei,Huang, Wenyu
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p. 4266 - 4270
(2017/04/03)
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- Base-Promoted Cascade Approach for the Preparation of Reduced Knoevenagel Adducts Using Hantzsch Esters as Reducing Agent in Water
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A cascade Knoevenagel condensation-reduction approach, which was carried out in water, has been reported. Using Hantzsch esters as reducing agent, under the promotion of base, a variety of reduced Knoevenagel adducts could be easily prepared by direct alkylation of malononitrile, ethyl 2-cyanoacetate, and 2-(4-nitrophenyl)acetonitrile, respectively. Meanwhile, a gram-scale synthesis of the protocol was also realized with excellent isolated yield.
- He, Tao,Shi, Ronghua,Gong, Yimou,Jiang, Guangyou,Liu, Ming,Qian, Shan,Wang, Zhouyu
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supporting information
p. 1864 - 1869
(2016/07/16)
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- Sterically Demanding Oxidative Amidation of α-Substituted Malononitriles with Amines Using O2
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An efficient amidation method between readily available 1,1-dicyanoalkanes and either chiral or nonchiral amines was realized simply with molecular oxygen and a carbonate base. This oxidative protocol can be applied to both sterically and electronically challenging substrates in a highly chemoselective, practical, and rapid manner. The use of cyclopropyl and thioether substrates support the radical formation of α-peroxy malononitrile species, which can cyclize to dioxiranes that can monooxygenate malononitrile α-carbanions to afford activated acyl cyanides capable of reacting with amine nucleophiles.
- Li, Jing,Lear, Martin J.,Hayashi, Yujiro
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p. 9060 - 9064
(2016/07/26)
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- A convenient heterogeneous reduction of knoevenagel product by Hantzsch ester and its development into reductive alkylation of malononitrile
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Poor solubility of Hantzsch ester is used as indicator in the reduction of methylidene malononitrile. The Knoevenagel reaction is integrated to develop a reductive alkylation of malononitrile with aryl and aliphatic aldehyde as the carbonyl substrate. Cop
- Yang, Yong-Qing,Lu, Zheng
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p. 650 - 653
(2014/07/22)
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- Discovery of mixed type thymidine phosphorylase inhibitors endowed with antiangiogenic properties: Synthesis, pharmacological evaluation and molecular docking study of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones. Part II
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In our drug discovery program, a series of 2-thioxo-pyrazolo[1,5-a][1,3,5] triazin-4-ones were designed, synthesized and evaluated for their TP inhibitory potential. All the synthesized analogues conferred a varying degree of TP inhibitory activity, comparable or better than positive control, 7-deazaxanthine (7-DX, 2) (IC50 value = 42.63 μM). A systematic approach to the lead optimization identified compounds 3c and 4a as the most promising TP inhibitors, exhibiting mixed mode of enzyme inhibition. Moreover, selected compounds demonstrated the ability to attenuate the expression of the angiogenic markers (viz. MMP-9 and VEGF) in MDA-MB-231 cells at sublethal concentrations. In addition, molecular docking studies revealed the plausible binding orientation of these inhibitors towards TP, which was in accordance with the experimental results. Taken as a whole, these compounds would constitute a new direction for the design of novel TP inhibitors with promising antiangiogenic properties.
- Bera, Hriday,Ojha, Probir Kumar,Tan, Bee Jen,Sun, Lingyi,Dolzhenko, Anton V.,Chui, Wai-Keung,Chiu, Gigi Ngar Chee
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p. 294 - 303
(2014/04/17)
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- A route to highly functionalized-enaminoesters via a domino ring-opening cyclization/decarboxylative tautomerization sequence of donor-acceptor cyclopropanes with substituted malononitriles
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An unprecedented and domino synthetic strategy for the synthesis of highly functionalized carbocyclic-enaminoesters bearing an all-carbon quaternary center via Yb(OTf)3-catalyzed ring-opening cyclization/decarboxylative tautomerization of donor-acceptor cyclopropanes with 2-alkyl malononitriles in excellent yields is described. The products are obtained as a single diastereomer in most cases where the nitrile and aryl groups are aligning in a cis orientation across the ring.
- Ghorai, Manas K.,Talukdar, Ranadeep,Tiwari, Deo Prakash
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supporting information
p. 2204 - 2207
(2014/05/06)
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- Catalyst-free chemoselective reduction of the carbon-carbon double bond in conjugated alkenes with Hantzsch esters in water
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A simple, efficient and green protocol for chemoselective reduction of carbon-carbon double bond in conjugated alkenes with Hantzsch esters is described. Without any additional catalysts, a series of conjugated alkenes with strong electron-withdrawing groups were reduced in water with excellent yield. Functional groups such as nitrile, ester, nitro, fluoro, chloro, bromo, furanyl and benzyl are all tolerated by the reaction conditions employed. The Royal Society of Chemistry.
- He, Qi,Xu, Zhihong,Jiang, Dehong,Ai, Wensi,Shi, Ronghua,Qian, Shan,Wang, Zhouyu
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p. 8671 - 8674
(2014/03/21)
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- An efficient green multi-component reaction strategy for the synthesis of highly functionalised pyridines and evaluation of their antibacterial activities
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An efficient green multi-component reaction (MCR) method has been developed for the synthesis of 2-amino-4-aryl/heteroaryl-6-(pyridin-2-ylthio)pyridine-3, 5-dicarbonitrile(s) via a 3-component reaction of aryl aldehyde(s), malononitrile and 2-mercaptopyridine in the presence of K2CO 3 under solvent free reaction conditions (SFRC) using grinding technique at room temperature in a single step. The advantages of the present protocol is operationally simple, environmentally benign, solvent-free reaction conditions (SFRC), simple work up, excellent isolated yields of desired products and viable method for large scale applications in pharmaceutical industry. Interestingly, the synthesized compounds showed moderate to excellent antibacterial activities against Gram-positive and Gram-negative bacterial strains.
- Reddy, Lakkireddy Srinivasula,Reddy, Tirumalareddy Ram,Mohan, Reddy Bodireddy,Mahesh, Avula,Lingappa, Yeramanchi,Reddy, Nallagondu Chinna Gangi
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p. 1114 - 1120
(2014/01/06)
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- An efficient chemoselective reduction of furan series unsaturated dinitriles
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An efficient reduction of double bonds conjugated with nitrile groups and acid or base sensitive furan rings with 2-phenylbenzimidazoline generated in situ has been successfully accomplished with high yields and excellent selectivity. The employed reducin
- Bobal, Pavel,Bobalova, Janette
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p. 2212 - 2221
(2013/04/10)
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- HAP-Pd(0): A highly efficient recyclable heterogeneous catalyst for the selective reduction of carbon-carbon double bond in ,-unsaturated ketones
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A recyclable heterogeneous hydroxyapatite-supported palladium(0) catalyst was prepared by a simple procedure and successfully applied for the selective reduction of carbon-carbon double bond in ,-unsaturated ketones using HCOONH4 as hydrogen transfer agen
- Chambyal, Omkar Singh,Paul, Satya,Shamim, Tahira,Gupta, Monika,Gupta, Rajive,Loupy, Andre
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p. 656 - 667
(2013/01/15)
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- One-pot multistep cascade reactions over multifunctional nanocomposites with pd nanoparticles supported on amine-modified mesoporous silica
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Two kinds of multifunctional nanocomposites, SBA-15-NH2/Pd-p and SBA-15-NH2/Pd-f, with platelet-like and fiber-like morphologies, respectively, were fabricated by immobilizing Pd NPs onto amine-functionalized SBA-15. Some of the amino groups acted as anchoring sites for Pd NPs, whilst the remaining groups acted as Bronsted basic sites. As a result, the composites served as excellent multifunctional heterogeneous catalysts for one-pot multistep cascade reaction sequences. Moreover,when diffusion was the rate-determine step, SBA-15-NH2/Pd-p, with small mesopores, was superior to the fiber-like control sample, owing to its short diffusion length, a lower possibility of pore clogging, and better mass transportation for the reaction species during the catalysis.
- Li, Ping,Liu, Hua,Yu, Yu,Cao, Chang-Yan,Song, Wei-Guo
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p. 2459 - 2465
(2013/10/08)
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- HETEROCYCLIC COMPOUNDS FOR THE INHIBITION OF PASK
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Disclosed herein are new heterocyclic compounds and compositions and their application as pharmaceuticals for the treatment of disease. Methods of inhibiting PAS Kinase (PASK) activity in a human or animal subject are also provided for the treatment of diseases such as diabetes mellitus.
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Page/Page column 56
(2012/11/08)
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- N-heterocyclic carbene boranes are good hydride donors
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The nucleophilicity parameters (N) of 1,3-bis(2,6-diisopropylphenyl) imidazol-2-ylidene borane and 1,3-dimethylimidazol-2-ylidene borane are 9.55 and 11.88. This places N-heterocyclic carbene boranes (NHC-boranes) among the most nucleophilic classes of neutral hydride donors. Reductions of highly electron-poor C=N and C=C bonds provide hydrogenation products along with new, stable borylated products. The results suggest that NHC-boranes have considerable untapped potential as neutral organic reductants.
- Horn, Markus,Mayr, Herbert,Lacote, Emmanuel,Merling, Everett,Deaner, Jordan,Wells, Sarah,McFadden, Timothy,Curran, Dennis P.
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supporting information; experimental part
p. 82 - 85
(2012/02/16)
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- Study on comparison of reducing ability of three organic hydride compounds
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Selective reduction of three kinds of substrates were studied to evaluate the reducing abilities of N,N-dimethyl-benzimidazolidine (DMBI), 2-phenylbenzimidazoline (PBI) and 2-phenylbenzothiazoline (PBT). As hydride donors, these three five-membered heterocyclic compounds performed different reducing abilities depending on the substrates.
- Feng, Yi-Si,Yang, Chun-Yan,Huang, Qiang,Xu, Hua-Jian
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p. 5053 - 5059
(2012/07/28)
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- Iron(III)/NaBH4-mediated additions to unactivated alkenes: Synthesis of novel 20′-vinblastine analogues
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An Fe(III)/NaBH4-mediated reaction for the functionalization of unactivated alkenes is described defining the alkene substrate scope, establishing the exclusive Markovnikov addition, exploring a range of free radical traps, examining the Fe(III) salt and initiating hydride source, introducing H2O-cosolvent mixtures, and exploring catalytic variants. Its use led to the preparation of a novel, potent, and previously inaccessible C20′-vinblastine analogue.
- Leggans, Erick K.,Barker, Timothy J.,Duncan, Katharine K.,Boger, Dale L.
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supporting information; scheme or table
p. 1428 - 1431
(2012/05/05)
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- Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
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Metal-free transfer hydrogenation of polarized olefins (RR′ CCEE′: R, R′ = H or organyl, E, E′ = CN or CO2Me) using amine borane adducts RR′NH-BH3 (R = R′ = H, AB; R = Me, R′ = H, MAB; R = tBu, R′ = H, tBAB; R = R′ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concerted transition state. The very reactive intermediate [NH2BH2] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy2BNH2. The final product borazine (BHNH)3 is assumed to be formed by dehydrocoupling of [NH2BH2] or its solvent stabilized derivative [NH2BH2]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH2NH 2)3 which is the trimerization product of [NH 2BH2].
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
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experimental part
p. 852 - 860
(2012/02/05)
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- Rh-catalyzed one-pot reductive alkylation of malononitrile under transfer hydrogenation conditions
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Efficient synthesis of monosubstituted malononitriles was achieved by one-pot reductive alkylation of malononitrile with carbonyl compounds via [Cp*RhCl2]2-catalyzed transfer hydrogenation reaction.
- Wu, Jiashou,Jiang, Huajiang
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experimental part
p. 1218 - 1226
(2011/05/04)
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- Facile metal free regioselective transfer hydrogenation of polarized olefins with ammonia borane
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Transfer hydrogenation of polarized olefins bearing strongly electron-withdrawing groups on one side of the double bond was achieved with ammonia borane under mild conditions without using a catalyst. Mechanistic studies proved the character of the direct H transfers proceeding stepwise with a unique hydroboration intermediate and hydride before proton transfer.
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
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p. 2053 - 2055
(2011/03/22)
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- Homogeneous hydrogenation of electron-deficient alkenes by iridium complexes
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The catalytic homogeneous hydrogenation of electron-deficient alkenes (nucleophilic hydrogenation) was achieved in the presence of iridium complexes and a base as co-catalyst. Contrary to hydrogenation of electron-rich alkenes, which is inactivated by bases, the hydrogenation of the electron-deficient alkenes turned out to be base activated. Here, we present a more thorough study on the capacities but also limitations of this new reaction mechanism using screenings of the reaction conditions as well as different Ir complexes and substrates. The formation of a catalytically active Ir complex is proposed. The active complex usually attacks a soft electron-deficient atom, if more than one possibility exists (as shown by density functional theory computations). Additionally, first examples of enantiomeric enrichments in the presence of chiral Ir complexes are presented. The high catalyst load needed and the moderate yields show that the active complex is very unstable under conditions of nucleophilic hydrogenation and is quickly deactivated, which has to be addressed in further studies. Copyright
- Semeniuchenko, Volodymyr,Exner, Thomas E.,Khilya, Volodymyr,Groth, Ulrich
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experimental part
p. 804 - 809
(2012/03/26)
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- Radical migration of substituents of aryl groups on quinazolinones derived from N-Acyl cyanamides
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A newly designed radical cascade involving N-acyl cyanamides is reported. It builds on aromatic homolytic substitutions as intermediate events and leads to complex heteroaromatic structures via an unprecedented radical migration of a substituent on aryl groups of quinazolinones (hydrogen or alkyl). Mechanistic considerations are detailed, which allowed us to devise fine control over the domino processes. The latter could be predictably stopped at several stages, depending on the reaction conditions. Finally, a surgical introduction of a trifluoromethyl substituent on a quinazolinone was achieved via the reported migration.
- Larraufie, Marie-Helene,Courillon, Christine,Ollivier, Cyril,Lacote, Emmanuel,Malacria, Max,Fensterbank, Louis
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supporting information; experimental part
p. 4381 - 4387
(2010/05/15)
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- Polymer-supported hantzsch 1,4-dihydropyridine ester: An efficient biomimetic hydrogen source for the reduction of ketimines and electron-withdrawing group conjugated olefins
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A polymer-supported Hantzsch 1,4-dihydropyridine ester was observed to be a useful selective reducing agent for the reduction of ketimines and electron-withdrawing conjugated olefins. The rate of the reduction of electron-withdrawing conjugated olefins is dependent on the nature of the conjugated substituents and could be enhanced by microwave irradiation. The reduction of (Z)-α-cyano-β-bromomethylcinnamates to cyclopropane derivatives using polymer-supported Hantzsch 1,4-dihydropyridine ester was found to proceed stereoselectively and in good yields.
- Che, Jun,Lam, Yulin
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experimental part
p. 1752 - 1758
(2010/09/11)
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- Exploring catalyst and solvent effects in the multicomponent synthesis of pyridine-3,5-dicarbonitriles
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(Chemical Equation Presented) The effects of an ionic base, tetrabutylammoniumhydroxide (TBAH), and an amine base, piperidine, on the direct synthesis of pyridine-3,5-dicarbonitriles using a multicomponent reaction (MCR) from aldehydes, malononitrile, and
- Guo, Kai,Thompson, Mark J.,Chen, Beining
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supporting information; experimental part
p. 6999 - 7006
(2009/12/07)
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- Nucleophilic homogeneous hydrogenation by iridium complexes
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Catalytic homogeneous hydrogenation of 7-methoxy-3-phenylchromone and other substrates was achieved in the presence of cationic iridium complexes and base as co-catalyst. Contrary to common alkene hydrogenation, which is inactivated by base, the hydrogena
- Semeniuchenko, Volodymyr,Khily, Volodymyr,Groth, Ulrich
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experimental part
p. 271 - 275
(2009/07/11)
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- Development of pharmaceutical drugs, drug intermediates and ingredients by using direct organo-click reactions
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Here we report on our studies of the use of combinations of amino acids, amines, K2CO3 or Cs2CO3 and CuSO4/Cu for catalysing green cascade reactions. We aimed to prepare the highly reactive and substituted olefin species 7 and 8, under very mild and environmentally friendly conditions, thus giving the hydrogenated products 10 and 12 through the action of Hantzsch ester (4) by self-catalysis through decreasing the HOMO-LUMO energy gaps between olefins 7/8 and Hantzsch ester (4) through biomimetic reductions. Highly useful compounds 10 to 14 were assembled from simple substrates such as aldehydes 1, ketones 2, CH acids 3, Hantzsch ester (4) and alkyl halides 5 by diversity-oriented green synthesis involving cascade olefination/hydrogenation (O/H), olefination/hydrogenation/alkylation (O/H/A) and hydrogenation/olefination/hydrogenation (H/O/H) reaction sequences in one-pot fashion with stereospecific organo- and organo-/metal-carbonate catalysis. Highly functionalized diverse compounds such as 10 to 14 are biologically active products and have found wide applications as pharmaceutical drugs, drug intermediates and drug ingredients. For the first time in organocatalysis, we report the O/H/A/TE reaction to furnish high yields of transesterification products 11 by simply mixing the reactants under proline/K2CO3 catalysis conditions. Additionally, a novel organocatalytic H/O/H reaction sequence for the synthesis of alkyl-substituted aromatics has been developed. Furthermore, for the first time we have developed organocatalysed cascade olefination/hydrogenation/hydrolysis (O/H/H) reactions to furnish highly useful materials such as 2-oxochroman-3-carboxylic acid (14kc) and 2-amino-4H-chromene-3-carbonitrile (14kj) in good yields. Experimentally simple and environmentally friendly organocatalytic two-carbon homologation through cascade O/H/H reactions of aldehydes 1, Meldrum's acid (3c), Hantzsch ester (4) and acetic acid/triethylamine in ethanol has been demonstrated. Additionally, we have developed a green synthesis of the highly substituted 1,2,3-triazole 17 from simple substrates through a two-step combination of olefination/hydrogenation/alkylation and Huisgen cycloaddition reaction sequences under stereospecific organocopper catalysis conditions. In this paper we have found strong support for our hypothesis that, "decreasing the HOMO-LUMO energy gap between olefins 7/8 and Hantzsch ester (4) will drive the biomimetic hydrogenation reaction by self-catalysis". This self-catalysis was further confirmed with many varieties of examples. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Ramachary, Dhevalapally B.,Kishor, Mamillapalli,Reddy, Y. Vijayendar
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supporting information; experimental part
p. 975 - 993
(2009/04/11)
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- Studies with malononitrile derivatives: Synthesis and reactivity of 4-benzylpyrazole-3,5-diamine, 4-benzylisoxazole-3,5-diamine and thiazolidin-3-phenylpropanenitrile
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Benzylmalononitrile 6 reacts with hydrazines, and hydroxylamine hydrochloride to yield the 4-benzylpyrazole-3,5-diamines 7 and 4-benzylisoxazol- e-3,5-diamine 9, respectively. Pyrazole-3,5-diamines 7 could be readily reacted with α,β-unsaturated nitriles
- Al-Mousawi, Saleh Mohammed,Moustafa, Moustafa Sherief,Elnagdi, Mohamed Hilmy
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experimental part
p. 1371 - 1383
(2009/04/06)
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- 3-Butyl-1-methylimidazolinium borohydride ([bmim][BH4])-a novel reducing agent for the selective reduction of carbon-carbon double bonds in activated conjugated alkenes
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A novel ionic reducing reagent, 3-butyl-1-methylimidazolium borohydride ([bmim][BH4]), was synthesized and successfully used for the selective reduction of carbon-carbon double bonds in conjugated alkenes as well as the α,β-carbon-carbon double bonds in highly activated α,β,γ,δ-unsaturated alkenes. The reagent can be regenerated and reused several times without losing its activity.
- Wang, Jiayi,Song, Gonghua,Peng, Yanqing,Zhu, Yidong
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supporting information; experimental part
p. 6518 - 6520
(2009/04/06)
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- Superacid-catalyzed intramolecular cyclization reaction of arylcyanopropionate: Geminal substitution effect on superelectrophilicity
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(Chemical Equation Presented) We present superacid-catalyzed intramolecular cyclization reactions of arylcyanopropionates to give cyclized five- and six-membered β-enamino esters in moderate to high yields. Known intramolecular ring-closing reactions of protonated nitrile to aromatic carbon atom are limited to the 6-membered case. Interestingly, a significant synergistic increase of reactivity of the cyano functionality was observed, and the cyano nitrogen atom was converted into an amino group, when an ester group was present in a geminal arrangement. Deuterium exchange experiments excluded the involvement of deprotonation of the α-proton in the cyclization process. The acidity dependence of the cyclization reactions and 13C NMR studies of a model compound, methyl cyanoacetate, in various acidic media were consistent with the involvement of the O,N-diprotonated dication of methyl cyanoacetate, a distonic dication, in strong acid, and this is considered to be the de facto electrophile in the present cyclization reaction of arylcyanopropionates.
- Nakamura, Satoshi,Sugimoto, Hiromichi,Ohwada, Tomohiko
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p. 4219 - 4224
(2008/09/20)
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- Monosubstituted malononitriles: Efficient one-pot reductive alkylations of malononitrile with aromatic aldehydes
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A powerful new one-pot method has been developed for the reductive alkylation of malononitrile with aromatic aldehydes. This new procedure has vastly improved the yield and efficiency of the process, and increased the scope of the aromatic aldehydes. Inco
- Tayyari, Fariba,Wood, Dwight E.,Fanwick, Phillip E.,Sammelson, Robert E.
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p. 279 - 285
(2008/12/22)
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- Nanocrystalline ZnO for Knoevenagel condensation and reduction of the carbon, carbon double bond in conjugated alkenes
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A novel efficient and eco-friendly nanocrystalline ZnO catalyst was used for the Knoevenagel condensation and for the reduction of C=C double bonds at room temperature in the absence of solvents.
- Hosseini-Sarvari, Mona,Sharghi, Hashem,Etemad, Samane
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scheme or table
p. 715 - 724
(2009/02/07)
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- Unprecedented reaction between ethyl α-cyanocinnamate and o-phenylenediamine: Development of an efficient method for the transfer hydrogenation of electronically depleted olefins
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A reaction between ethyl α-cyanocinnamate and o-phenylenediamine under thermal conditions yielded 2-cyano-3-phenyl-propionic acid ethyl ester, 2-phenyl benzimidazole, and ethyl cyanoacetate. The mechanistic revelations led to the development of a simple and efficient transfer-hydrogenation process from the in situ generated benzimidazolines to activated olefins under solventless and catalyst-free conditions. Georg Thieme Verlag Stuttgart.
- Kumar, Satish,Kapoor, Kamal K.
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p. 2809 - 2814
(2008/02/13)
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- A novel and green protocol for two-carbon homologation: A direct amino acid/K2CO3-catalyzed four-component reaction of aldehydes, active methylenes, Hantzsch esters and alkyl halides
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A novel and green approach for the two-carbon homologation of aldehydes using amino acid catalysis has been developed and further extended to the generation of pharmaceutically active cyano-esters via four-component reactions in one-pot.
- Ramachary, Dhevalapally B.,Kishor,Ramakumar
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p. 651 - 656
(2007/10/03)
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- Towards organo-click reactions: Development of pharmaceutical ingredients by using direct organocatalytic bio-mimetic reductions
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Economic and environmentally friendly bio-mimetic one-pot three and four-component Knoevenagel-hydrogenation (K-H), five-component Knoevenagel-hydrogenation-alkylation (K-H-A) and six-component Knoevenagel-hydrogenation-alkylation-Huisgen cycloaddition (K-H-A-HC) reactions of aldehydes, CH-acids, o-phenylenediamine, alkyl halides and azides using proline, proline-metal carbonate and proline-metal carbonate-Cu I-catalysis, respectively have been developed. Many of K-H and K-H-A compounds have direct application in pharmaceutical chemistry. The Royal Society of Chemistry.
- Ramachary, Dhevalapally B.,Reddy, G. Babul
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p. 4463 - 4468
(2008/09/19)
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- Expanding the utility of one-pot multistep reaction networks through compartmentation and recovery of the catalyst
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Controlled catalysis: The combination of magnetically and gravimetrically recoverable catalysts such as the nanoparticle-bound base (see picture; blue) and the resin-bound acid (green), respectively, allow the application of non-complementary catalysts to multistep, one-pot reaction cascades (e.g. A→B→C). The catalysts are recovered after reaction and reused in subsequent, unrelated reactions. (Figure Presented)
- Phan, Nam T. S.,Gill, Christopher S.,Nguyen, Joseph V.,Zhang, Z. John,Jones, Christopher W.
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p. 2209 - 2212
(2007/10/03)
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- Ruthenium catalysed reduction of alkenes using sodium borohydride
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The reduction of alkenes has been achieved using NaBH4 as the reducing agent using 0.5-1.0 mol % Ru(PPh3)4H2 in the presence of water.
- Adair, Gareth R.A.,Kapoor, Kamal K.,Scolan, Alexandre L.B.,Williams, Jonathan M.J.
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p. 8943 - 8944
(2007/10/03)
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