- 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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p. 7832 - 7841
(2021/06/25)
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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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p. 5901 - 5905
(2021/03/09)
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- Tandem Condensation-Hydrogenation to Produce Alkylated Nitriles Using Bifunctional Catalysts: Platinum Nanoparticles Supported on MOF-Derived Carbon
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Tandem catalysis, which allows multiple steps of a reaction to take place without the need for separation and purification, is highly desired for the design of efficient and environmentally-friendly chemical processes. Herein, the pyrolysis of UiO-66-NHs
- Huang, Ao,Nie, Renfeng,Zhang, Biying,Pei, Yuchen,Chen, Minda,Behera, Ranjan,Yu, Jiaqi,Luan, Xuechen,Hunter, Nicholas T.,Ke, Ming,Huang, Wenyu
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p. 602 - 608
(2019/12/27)
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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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p. 5572 - 5584
(2017/12/07)
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- Mechanistic Investigations of Reactions of the Frustrated Lewis Pairs (Triarylphosphines/B(C6F5)3) with Michael Acceptors
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Frustrated Lewis pair (FLP)-catalyzed reduction of Michael acceptors is a challenging reaction that proceeds with specific FLP structures. Kinetics and equilibrium of the reactions of two phosphines (Ar3P), namely tri(1-naphthyl)phosphine and tri(o-tolyl)phosphine, are reported with reference electrophiles. The reason for the failure of the FLPs (Ar3P/B(C6F5)3) to reduce activated alkenes under H2 pressure is shown to be a hydrophosphination process that inhibits the reduction reaction. Kinetic and thermodynamic factors controlling both pathways are discussed in light of Mayr's free linear energy relationships.
- Dupré, Jonathan,Gaumont, Annie-Claude,Lakhdar, Sami
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supporting information
p. 694 - 697
(2017/02/10)
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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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- 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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p. 7317 - 7322
(2016/10/29)
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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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- 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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- 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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- The synthesis of some derivatives based on the 4-Benzyl-1H-Pyrazole-3,5- Diamine core
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The three-step synthesis of 4-benzyl-1H-pyrazole-3,5-diamines 2 from commercially available aldehydes 3 is given. The Knoevenagel condensation was utilized to assemble the initial carbon framework, resulting in the benzylidenemalononitriles 4 which were d
- Jedinak, Lukas,Krystof, Vladimir,Cankara, Petr
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p. 371 - 383
(2011/04/15)
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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; scheme or table
p. 6518 - 6520
(2009/04/06)
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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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- 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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p. 680 - 686
(2007/10/03)
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- A facile experimental method to determine the hydride affinity of polarized olefins in acetonitrile
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(Chemical Equation Presented) Choosing a suitable hydride reducing agent and thermodynamic analysis of reduction mechanisms is facilitated by experimental hydride affinities ΔHH-A, which are reported herein for 28 polarized olefins 1 in acetonitrile (see scheme). The method should also be applicable to ketones, aldehydes, and imines.
- Zhu, Xiao-Qing,Zhang, Min,Liu, Qiao-Yun,Wang, Xiao-Xiao,Zhang, Jian-Yu,Cheng, Jin-Pei
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p. 3954 - 3957
(2007/10/03)
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- Co-immobilized formate anion and palladium on a polymer surface: A novel heterogeneous combination for transfer hydrogenation
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A novel heterogeneous combination of a formate reagent and palladium catalyst co-immobilized on a resin support has been developed and shown to be highly efficient and recyclable for transfer hydrogenation of alkenes, imines, nitroarenes and 1,2-dicarbonyl compounds.
- Basu, Basudeb,Das, Sajal,Das, Pralay,Nanda, Ashish K.
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p. 8591 - 8593
(2007/10/03)
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- Efficient role of Mg-ZnCl2 for selective reduction of α,β-unsaturated carbonyl compounds in aqueous medium
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A facile strategy for the convenient reduction of α,β- unsaturated carbonyl compounds and conjugated alkynes has been accomplished by Mg-ZnCl2 system in aqueous medium. Georg Thieme Verlag Stuttgart.
- Saikia, Anil,Barthakur, Madan Gopal,Boruah, Romesh Chandra
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p. 523 - 525
(2007/10/03)
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- Catalytic transfer reduction of conjugated alkenes and an imine using polymer-supported formates
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An efficient and mild method for catalytic transfer hydrogenation of C=C and C=N double bonds with the aid of resin-supported formate (PSF) as the hydrogen donor and palladium acetate as the catalyst is reported.
- Basu, Basudeb,Bhuiyan, Md. Mosharef H.,Das, Pralay,Hossain, Ismail
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p. 8931 - 8934
(2007/10/03)
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- Polysiloxane-supported NAD(P)H model 1-benzyl-1,4-dihydronicotinamide: Synthesis and application in the reduction of activated olefins
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A new polysiloxane-supported NAD(P)H model, 1-benzyl-1,4-dihydronicotinamide, was designed and synthesized, which can efficiently reduce many activated olefins under mild conditions. The most advantageous features of this new polysiloxane-supported reductant are (i) easy workup and separation of the reaction products and (ii) good potential for recycling use of the reductant, which makes this new polysiloxane-supported NAD(P)H model a promising alternative both in research laboratories and in industrial processes.
- Zhang, Baolian,Zhu, Xiao-Qing,Lu, Jin-Yong,He, Jiaqi,Wang, Peng G.,Cheng, Jin-Pei
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p. 3295 - 3298
(2007/10/03)
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- Enantioselective biotransformation of α,α-disubstituted dinitriles to the corresponding 2-cyanoacetamides using Rhodococcus sp. CGMCC 0497
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A new application of nitrile-converting enzymes in the synthesis of optically active α,α-disubstituted-α-cyanoacetamides from α,α-disubstituted-malononitriles with whole cells of Rhodococcus sp. CGMCC 0497 is described. The products were obtained with enantiomeric excesses of up to >99%, and yields of up to 53%. They are very useful chiral intermediates especially for the synthesis of chiral α,α-disubstituted amino acids but have never been synthesized directly by chemical or enzymatic methods.
- Wu, Zhong-Liu,Li, Zu-Yi
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p. 2133 - 2142
(2007/10/03)
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- Indium metal as a reducing agent. Selective reduction of the carbon-carbon double bond in highly activated conjugated alkenes
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(Equation presented) Indium metal in aqueous ethanolic ammonium chloride reduces the C=C bond in highly activated conjugated alkenes such as α,α-dicyano olefins, β-arylenones, and enone esters.
- Ranu, Brindaban C.,Dutta, Jyotirmoy,Guchhait, Sankar K.
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p. 2603 - 2605
(2007/10/03)
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- A detailed investigation into the oxidation mechanism in Hantzsch 1,4-dihydropyridines by ethyl a-cyanocinnamates and benzylidenemalononitriles
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A mechanism for the oxidation of Hantzsch 1,4-dihydropyridine (HEH) by substituted ethyl a-cyanocinnamates (1) and benzylidenemalononitriles (2) has been critically investigated. Replacement of HEH by HEH-4,4-d2 and HEH-N-d gave the observed kinetic isotope effects (KIE) of 5.3-6.0 and 1.2-1.3 for the reactions with 1 and 2, respectively, which suggests C4-H bond dissociation is involved in the rate-limiting step and that the N-H bond dissociation is a non-rate-limiting step. The positive ρ values of 1.78 and 1.67 for the reactions of HEH with 1 and 2, respectively, clearly demonstrate the electrophilic nature of the substrates in the transition state (TS) and so indicate that the hydrogen lost from HEH must be a hydride-like species. Correlation analyses on the kinetics, KIE's and activation parameters showed excellent linear dependence on the electronic properties of remote substituents and added further credence to the proposed one-step hydride transfer mechanism. Detailed investigation of the activation parameters not only confirmed the direct HT- mechanism, but also revealed experimentally, for the first time, an entropy-controlled compact TS for the HEH-modeled NAD(P)H oxidations.
- Zhu, Xiao-Qing,Zou, Hong-Ling,Yuan, Ping-Wei,Cao, Lei,Cheng, Jin-Pei
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p. 1857 - 1861
(2007/10/03)
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- Photochemical carbon-silicon bond forming reaction on electron-deficient alkenes by disilanes and polysilanes via photoinduced electron transfer
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The phenanthrene-sensitized photoreaction of electron-deficient alkenes with disilanes in acetonitrile gave silylated alkanes in high yields.The photosilylation occurred in a highly regioselective manner at the position β to the electron-withdrawing group
- Mizuno, Kazuhiko,Nakanishi, Kazuhisa,Chosa, Jun-ichi,Otsuji, Yoshio
-
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- PHOTOSILYLATION OF ELECTRON-DEFICIENT ALKENES BY USE OF DISILANES VIA PHOTOINDUCED ELECTRON-TRANSFER
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The photosilylation on electron-deficient alkenes such as 1-aryl-2,2-dicyanoethenes occurred regioselectively at the β-position to the electron-withdrawing groups upon irradiation with disilanes and trisilane.
- Mizuno, Kazuhiko,Nakanishi, Kazuhisa,Chosa, Jun-ichi,Nguyen, Tien,Otsuji, Yoshio
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p. 3689 - 3692
(2007/10/02)
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- THE REACTIONS OF BENZYLIDENEMALONONITRILES AND β-NITROSTYRENES WITH O-PHENYLENEDIAMINE INCLUDING THE NEW ORGANIC REDOX REACTIONS BETWEEN THE OLEFINS AND 2-PHENYLBENZIMIDAZOLINES
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The reactions of benzylidenemalononitriles and β-nirtostyrenes with o-phenylenediamine in ethanol at boiling temperature gave the reduced products of the olefins.The reactions were rationalised on the basis of the role of 2-phenylbenzimidazolines as a hydrogen donor.
- Itoh, Kazuyoshi,Ishida, Hideaki,Chikashita, Hidenori
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p. 1117 - 1118
(2007/10/02)
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