- Condensation of β-diester titanium enolates with carbonyl substrates: A combined DFT and experimental investigation
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The condensation of dialkyl β-diesters with various aldehydes promoted by TiCl4 has been studied by DFT approaches and experimental methods, including NMR, IR and UV/ Vis spectroscopy. Various possible reaction pathways have been investigated a
- Marrone, Alessandro,Renzetti, Andrea,De Maria, Paolo,Gerard, Stephane,Sapi, Janos,Fontana, Antonella,Re, Nazzareno
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- Gadolinium triflate catalyzed alkylation of pyrroles: efficient synthesis of 3-oxo-2,3-dihydro-1H-pyrrolizine derivatives
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Novel 2-alkylated pyrrole derivatives were synthesized regioselectively by Gd(OTf)3 catalyzed addition reactions of pyrrole to?substituted dimethyl 2-benzylidenemalonate derivatives under mild reaction conditions. 2-Alkylated pyrrole derivative
- Unaleroglu, Canan,Yazici, Arife
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- NbCl5-Promoted Synthesis of 4-Aryl-3,4-dihydrocoumarins by Multicomponent Reaction
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Substituted 4-aryl-3,4-dihydrocoumarins are synthesized from multicomponent reactions between phenols, dimethyl malonate, and aryl aldehydes catalyzed by niobium pentachloride. This new method is simple, cost-effective, and high-yielding, and can be condu
- Dos Santos, Willian Henrique,Da Silva-Filho, Luiz Carlos
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- A novel sublimable organic salt: Synthesis, characterization, thermal behavior, and catalytic activity for the synthesis of arylidene, heteroarylidene, and alkylidene malonates
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A novel sublimable organic salt was synthesized, and its chemical structure was characterized by FTIR, 1D NMR, 2D NMR, and elemental analysis. In addition, the thermal phase transitions and thermal stability of new organic salt were investigated. The DSC and TGA results showed that the organic salt could convert into constituent molecules at dec. ~ 200?°C) under atmospheric pressure without forming the liquid phase. Then, it was recondensed to regenerate the initial organic salt in the cool part of the vial. Therefore, it can be a promising organic salt towards the regeneration of spent catalyst from synthesis processes when the reaction mixture contains poorly volatile components and includes its use in gas-phase procedures. Also, the catalytic efficiency of new organic salt was investigated in the Knoevenagel condensation reaction. A variety of substituted arylidene and alkylidene malonates were isolated in 78–95% yield within six hours.? Under the optimized reaction conditions, the current catalytic procedure exhibited superiority compared to the mixed piperazine/acetic acid, piperidine/acetic acid, and piperidinium acetate. There were no significant changes in the new organic salt chemical structure and catalytic activity even after the 5th run. This work revealed the importance of the existence of simultaneous hydrogen bond acceptor/donor groups in our environmentally friendly catalyst to promote the Knoevenagel condensation reaction without the use of metal-containing catalysts.
- Johari, Suzaimi,Zaharani, Lia,Gorjian, Hayedeh,Johan, Mohd R.,Khaligh, Nader G.
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p. 361 - 377
(2021/09/18)
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- Solid-phase synthesis of arylidene and alkylidene malonates, as versatile intermediates, catalyzed using mesoporous poly-melamine–formaldehyde as a nitrogen-rich porous organic polymer (POP)
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An efficient solid/slurry-state synthesis of arylidene and alkylidene malonates as versatile intermediates is developed in the presence of mesoporous poly-melamine–formaldehyde. The condensation reaction was conducted through a ball milling process as a non-conventional procedure and a greener methodology at room temperature under solvent-free conditions. The mesoporous heterogeneous catalyst could be recovered and reused ten times, and the results showed a negligible loss of catalytic activity. Various aryl- and heteroarylidene malonates, as well as dimethyl (cyclohexylidene)malonate, were isolated in good to high yields under optimal conditions. The use of hazardous reagents and solvents were minimized in the current method, and separation of catalyst and products, as well as the recovery and reusing of catalyst, were performed by cost-effective procedures. This work revealed that the synergistic effect of numerous Lewis base sites together with acceptor-donner hydrogen bonding functional groups in porous organic polymer (POP), and its high porosity plays a vital role to promote the carbon–carbon coupling reaction in the solid phase synthesis.
- Khaligh, Nader Ghaffari,Gorjian, Hayedeh,Fahim, Hoda,Titinchi, Salam J. J.
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p. 3529 - 3536
(2021/05/11)
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- Chemo- And regioselective ring-opening of donor-acceptor oxiranes with: N -heteroaromatics
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The first ring-opening of D-A oxiranes with N-heteroaromatics in a chemoselective C-C bond cleavage manner was achieved. In the presence of 5 mol% of Y(OTf)3 as the catalyst, diverse N-heteroaromatics, including benzotriazoles, purines, substituted benzim
- Sang, Ji-Wei,Xie, Ming-Sheng,Wang, Man-Man,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 4552 - 4555
(2021/05/17)
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- Reductive Knoevenagel Condensation with the Zn-AcOH System
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An efficient gram-scale one-pot approach to 2-substituted malonates and related structures is developed, starting from commercially available aldehydes and active methylene compounds. The technique combines Knoevenagel condensation with the reduction of the C=C bond in the resulting activated alkenes with the Zn-AcOH system. The relative ease with which the C=C bond reduction occurs can be traced to the accepting abilities of the substituents in the intermediate arylidene malonates.
- Ivanov, Konstantin L.,Melnikov, Mikhail Ya.,Budynina, Ekaterina M.
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p. 1285 - 1291
(2020/11/13)
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- Acetal Addition to Electron-Deficient Alkenes with Hydrogen Atom Transfer as a Radical Chain Propagation Step
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We describe a visible-light-promoted addition of a hydrogen atom and an acetal carbon toward various electron-deficient alkenes. 1,3-Dioxolane is converted to its radical species in the presence of persulfate and an iridium catalyst upon visible light irradiation, which then reacts with electron-deficient alkenes. The reaction operates via a radical chain mechanism, a less commonly observed pathway for this class of transformation. Hydrogen atom transfer from 1,3-dioxolane to α-malonyl radicals is corroborated by experimental and density functional theory studies.
- Chan, Wei Chuen,Vinod, Jincy K.,Koide, Kazunori
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p. 3674 - 3682
(2021/02/16)
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- Synthesis of Substituted β-Styrylmalonates by Sequential Isomerization of 2-Arylcyclopropane-1,1-dicarboxylates and (2-Arylethylidene)malonates
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A method has been developed for the synthesis of substituted β-styrylmalonates by conversion of 2-arylcyclopropane-1,1-dicarboxylates (ACDCs) in the presence of gallium trichloride into the corresponding- 1,2-zwitterionic intermediates or (2-arylethyl-idene)malonates, followed by treatment with pyridine at room temperature leading to an isomerization of the emerging double bond. This method allows one to expand these reactions to include ACDCs with acceptor substituents at the aromatic ring.
- Borisov, Denis D.,Chermashentsev, Grigorii R.,Novikov, Roman A.,Tomilov, Yury V.
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supporting information
p. 2253 - 2259
(2021/03/04)
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- Mild Darzens Annulations for the Assembly of Trifluoromethylthiolated (SCF3) Aziridine and Cyclopropane Structures
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We report mild new annulation approaches to trisubstituted trifluoromethylthiolated (SCF3) aziridines and cyclopropanes via Darzens inspired protocols. The products of these anionic annulations, rarely studied previously, possess attractive features rendering them valuable building blocks for synthesis platforms. In this study, trisubstituted acetophenone nucleophiles bearing SCF3 and bromine substituents in their α position were shown to undergo [2 + 1] annulations with vinyl ketones and tosyl-protected imines under mild reaction conditions.
- Delost, Michael D.,Njardarson, Jon T.
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supporting information
p. 6121 - 6125
(2021/08/16)
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- Electricity Driven 1,3-Oxohydroxylation of Donor-Acceptor Cyclopropanes: a Mild and Straightforward Access to β-Hydroxy Ketones
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An unprecedented external oxidant-free electrochemical protocol for 1, 3-oxohydroxylation of donor-acceptor cyclopropane is disclosed. The strategy encompasses the activation of the labile π-electron cloud of the aryl ring to cleave the strained Csp3?Csp3 bond of cyclopropane to afford the β-hydroxy ketones via insertion of molecular oxygen. More significantly, based on the detailed mechanistic investigations and cyclic voltammetry experiments, a plausible mechanism is proposed.
- Banerjee, Prabal,Maajid Taily, Irshad,Saha, Debarshi
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supporting information
p. 5053 - 5057
(2021/09/30)
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- Amides as surrogates of aldehydes for C-C bond formation: amide-based direct Knoevenagel-type condensation reaction and related reactions
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Aldehydes are perhaps the most versatile compounds that enable many C-C bond forming reactions, which are not amenable for other subclasses of carbonyl compounds. We report the first use of amides as surrogates of aldehydes for C-C bond formation, namely,
- Ou, Wei,Huang, Pei-Qiang
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- Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes: Scope and limitations
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Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes utilizing S-monofluoromethyl-S-phenyl-2,3,4,5-tetramethylphenylsulfonium tetrafluoroborate is an efficient approach to obtain a range of monofluorocyclopropane derivatives. So far, fluoromethylsulfonium salts have displayed the broadest scope for direct fluoromethylene transfer. In contrast to more commonly used fluorohalomethanes or freon derivatives, diarylfluoromethylsulfonium salts are bench stable, easy-to use reagents useful for the direct transfer of a fluoromethylene group to alkenes giving access to the challenging products-fluorocyclopropane derivatives. Interplay between the reactivity of the starting materials and stability of the fluorocyclopropanes formed determines the outcome of the process.
- Kazia, Armands,Melngaile, Renate,Mishnev, Anatoly,Veliks, Janis
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supporting information
p. 1384 - 1388
(2020/03/03)
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- Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
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Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
- An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
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supporting information
p. 6216 - 6226
(2020/04/27)
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- Metal free biomimetic deaminative direct C-C coupling of unprotected primary amines with active methylene compounds
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An unprecedented direct C-C coupling reaction of unprotected primary amines with active methylene compounds is reported. The reaction involves a biomimetic deamination of amines which was achieved under conditions free of metallic reagents and strong oxidizing agents. A wide range of primary amines was reacted with different active methylene compounds to provide structurally diverse trisubstituted alkenes and dihydropyridines. A kinetic study revealed an activation barrier of 10.1 kcal mol-1 for the conversion of a key intermediate of the reaction.
- Ghosh, Santanu,Jana, Chandan K.
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supporting information
p. 10153 - 10157
(2019/12/26)
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- General [4 + 1] Cyclization Approach to Access 2,2-Disubstituted Tetrahydrofurans Enabled by Electrophilic Bifunctional Peroxides
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A general [4 + 1] cyclization reaction of carbonyl nucleophiles with 2-iodomethylallyl peroxides, which function as unique electrophilic oxygen synthons, for the synthesis of a broad range of 2,2-disubstituted tetrahydrofurans is achieved under operationally simple conditions. The unprecedented asymmetric version of such reaction is also realized via chiral auxiliary-assisted cyclization, thus providing a distinct approach to access chiral tetrahydrofurans with high diastereoselectivities. The new method can be applied to the synthesis of core structure of posaconazole drug.
- Gao, Min,Zhao, Yukun,Zhong, Chen,Liu, Shengshu,Liu, Pengkang,Yin, Qi,Hu, Lin
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supporting information
p. 5679 - 5684
(2019/08/01)
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- Dehydroxymethylation of alcohols enabled by cerium photocatalysis
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Dehydroxymethylation, the direct conversion of alcohol feedstocks as alkyl synthons containing one less carbon atom, is an unconventional and underexplored strategy to exploit the ubiquity and robustness of alcohol materials. Under mild and redox-neutral reaction conditions, utilizing inexpensive cerium catalyst, the photocatalytic dehydroxymethylation platform has been furnished. Enabled by ligand-to-metal charge transfer catalysis, an alcohol functionality has been reliably transferred into nucleophilic radicals with the loss of one molecule of formaldehyde. Intriguingly, we found that the dehydroxymethylation process can be significantly promoted by the cerium catalyst, and the stabilization effect of the fragmented radicals also plays a significant role. This operationally simple protocol has enabled the direct utilization of primary alcohols as unconventional alkyl nucleophiles for radical-mediated 1,4-conjugate additions with Michael acceptors. A broad range of alcohols, from simple ethanol to complex nucleosides and steroids, have been successfully applied to this fragment coupling transformation. Furthermore, the modularity of this catalytic system has been demonstrated in diversified radical-mediated transformations including hydrogenation, amination, alkenylation, and oxidation.
- Zhang, Kaining,Chang, Liang,An, Qing,Wang, Xin,Zuo, Zhiwei
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supporting information
p. 10556 - 10564
(2019/08/20)
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- Dehydroxymethylation of Alcohols Enabled by Cerium Photocatalysis
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Dehydroxymethylation, the direct conversion of alcohol feedstocks as alkyl synthons containing one less carbon atom, is an unconventional and underexplored strategy to exploit the ubiquity and robustness of alcohol materials. Under mild and redox-neutral reaction conditions, utilizing inexpensive cerium catalyst, the photocatalytic dehydroxymethylation platform has been furnished. Enabled by ligand-to-metal charge transfer catalysis, an alcohol functionality has been reliably transferred into nucleophilic radicals with the loss of one molecule of formaldehyde. Intriguingly, we found that the dehydroxymethylation process can be significantly promoted by the cerium catalyst, and the stabilization effect of the fragmented radicals also plays a significant role. This operationally simple protocol has enabled the direct utilization of primary alcohols as unconventional alkyl nucleophiles for radical-mediated 1,4-conjugate additions with Michael acceptors. A broad range of alcohols, from simple ethanol to complex nucleosides and steroids, have been successfully applied to this fragment coupling transformation. Furthermore, the modularity of this catalytic system has been demonstrated in diversified radical-mediated transformations including hydrogenation, amination, alkenylation, and oxidation.
- Zhang, Kaining,Chang, Liang,An, Qing,Wang, Xin,Zuo, Zhiwei
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supporting information
p. 10556 - 10564
(2019/08/28)
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- Stereospecific copper(II)-catalyzed tandem ring opening/oxidative alkylation of donor-acceptor cyclopropanes with hydrazones: Synthesis of tetrahydropyridazines
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Aerobic copper(II)-catalyzed tandem ring opening and oxidative C-H alkylation of donor-acceptor cyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89-98% enantiomeric excess). The substrate scope, functional group tolerance, dual role of the copper(II) catalyst, and the use of air as an oxidant are the important practical features. A product bearing a 3-bromoaryl group can be subjected to Pd-catalyzed Suzuki coupling with boronic acid in high yield.
- Mishra, Manmath,De, Pinaki Bhusan,Pradhan, Sourav,Punniyamurthy, Tharmalingam
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p. 10901 - 10910
(2019/09/13)
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- Cu-Catalyzed Silylation and Borylation of Vinylidene Cyclopropanes
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A Cu-catalyzed addition of silicon or boron nucleophiles to vinylidene cyclopropanes is reported. The reactions generated propargylic silane or boron products by forming a C-Si or C-B bond at the terminal carbon of the allene moiety of vinylidene cyclopro
- Chen, Jichao,Gao, Shang,Chen, Ming
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supporting information
p. 8800 - 8804
(2019/11/11)
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- Amino- and sulfo-bifunctionalized hyper-crosslinked organic nanotube frameworks as efficient catalysts for one-pot cascade reactions
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In this paper, novel amino- and sulfo-bifunctionalized hyper-crosslinked organic nanotube frameworks (H-ONTFs) were directly prepared by templating core-shell bottlebrush copolymers via a Friedel-Crafts (F-C) alkylation reaction, in which the acidic sites were anchored into the wall of nanotubes and basic sites were introduced onto the inner layer wall of nanotubes through a rational molecular design strategy. The resulting acid-base bifunctionalized H-ONTFs showed excellent catalytic activities for one-pot deacetalization-Knoevenagel cascade reactions due to their open-ended structure, large surface area and good multi-porosity interconnectivity.
- Meng, Guojie,Gao, Shengguang,Liu, Ying,Zhang, Li,Song, Chunmei,Huang, Kun
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supporting information
p. 2269 - 2273
(2019/02/05)
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- Lewis acid-mediated reactions of donor-acceptor cyclopropanes with diazo esters
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The reactions of diazo esters with 2-arylcyclopropane-1,1-dicarboxylates, the represen- tatives of donor-acceptor cyclopropanes (DACs), mediated by Sc(OTf)3, SnCl4, and GaCl3 proceeded with nitrogen elimination to give the
- Novikov,Borisov,Tomilov, Yu. V.
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p. 265 - 273
(2018/05/15)
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- Enantioselective Catalyst Systems from Copper(II) Triflate and BINOL–Silanediol
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Silanediol and copper catalysis are merged, for the first time, to create an enhanced Lewis acid catalyst system for enantioselective heterocycle functionalization. The promise of this silanediol and copper catalyst combination is demonstrated in the enantioselective addition of indoles to alkylidene malonates to give rise to the desirable adducts in excellent yield and high enantiomeric excess. From these studies, 1,1′-bi-2-naphthol (BINOL)-based silanediols emerge as one-of-a-kind cocatalysts. Their potential role in the reaction pathway is also discussed.
- Guan, Yong,Attard, Jonathan W.,Visco, Michael D.,Fisher, Thomas J.,Mattson, Anita E.
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supporting information
p. 7123 - 7127
(2018/05/08)
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- An Expeditious Route to trans-Configured Tetrahydrothiophenes Enabled by Fe(OTf)3-Catalyzed [3+2] Cycloaddition of Donor–Acceptor Cyclopropanes with Thionoesters
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A synthetic route to trans-configured tetrahydrothiophenes (THTs) through Fe(OTf)3-promoted [3+2] cycloaddition of donor–acceptor cyclopropanes with thionoesters was developed. The cycloaddition proceeded in high yield with high diastereoselectivity, affording transient α-alkoxy THTs. Not only aromatic and aliphatic thionoesters, but also thionolactone were applicable to the present iron catalysis. Further transformation of the S,O-ketal functionality of the product was achieved in a highly trans diastereoselective manner. Moreover, the utility of our methodology was clearly demonstrated by the synthesis of enantioenriched trans-configured THTs.
- Matsumoto, Yohei,Nakatake, Daiki,Yazaki, Ryo,Ohshima, Takashi
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supporting information
p. 6062 - 6066
(2018/03/28)
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- Nucleophilic Ring Opening of Donor-Acceptor Cyclopropanes Catalyzed by a Br?nsted Acid in Hexafluoroisopropanol
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A general, Br?nsted acid catalyzed method for the room temperature, nucleophilic ring opening of donor-acceptor cyclopropanes in fluorinated alcohol solvent, HFIP, is described. Salient features of this method include an expanded cyclopropane scope, including those bearing single keto-acceptor groups and those bearing electron-deficient aryl groups. Notably, the catalytic system proved amenable to a wide range of nucleophiles including arenes, indoles, azides, diketones, and alcohols.
- Richmond, Edward,Vukovi?, Vuk D.,Moran, Joseph
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supporting information
p. 574 - 577
(2018/02/10)
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- Intermolecular Reductive Couplings of Arylidene Malonates via Lewis Acid/Photoredox Cooperative Catalysis
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A cooperative Lewis acid/photocatalytic reduction of arylidene malonates yields a versatile radical anion species. This intermediate preferentially undergoes intermolecular radical-radical coupling reactions, and not the conjugate addition-dimerization reactivity typically observed in the single-electron reduction of conjugate acceptors. Reported here is the development of this open-shell species in intermolecular radical-radical cross couplings, radical dimerizations, and transfer hydrogenations. This reactivity underscores the enabling modularity of cooperative catalysis and demonstrates the utility of stabilized enoate-derived radical anions in intermolecular bond forming reactions.
- McDonald, Benjamin R.,Scheidt, Karl A.
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supporting information
p. 6877 - 6881
(2018/11/02)
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- Highly Chemo- and Diastereoselective Dearomative [3 + 2] Cycloaddition Reactions of Benzazoles with Donor-Acceptor Oxiranes
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A Sc(OTf)3-catalyzed dearomative [3 + 2] cycloaddition of benzazoles with donor-acceptor oxiranes through chemoselective C-C bond cleavage of oxiranes was developed under mild conditions. This reaction provides an efficient method to construct benzazolo[3,2-c]oxazole compounds in good yields and with high diastereoselectivity. The reaction has a general substrate scope, and the donor-acceptor oxiranes with electron-donating and electron-withdrawing groups on the aromatic ring afforded the desired cycloadducts.
- Zhang, Shan-Shan,Wang, Dong-Chao,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 8026 - 8029
(2019/01/14)
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- Ionic Ga-Complexes of Alkylidene- And Arylmethylidenemalonates and Their Reactions with Acetylenes: An In-Depth Look into the Mechanism of the Occurring Gallium Chemistry
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A new synthetic concept was suggested in the chemistry of substituted methylidenemalonates that enables their utilization as 1,2-zwitterionic synthons. This strategy is to generate liquid ionic Ga complexes from methylidenemalonates and GaHal3with a strict 3/4 composition and then use them in further synthesis. A number of complexes with different metal halides have been synthesized and studied in detail. The unique properties of gallium among all metals have been demonstrated and explained. On the basis of the discovered new class of gallium complexes of methylidenemalonates, a number of novel reactions with acetylenes have been elaborated, which are unknown in the conventional chemistry of methylidenemalonates. The main demonstrated process is a three-component addition to a triple bond involving halide anions, leading to the formation of polyfunctional vinyl halides with highE-selectivity. The mechanism has been studied experimentally in fine detail. Application of specially optimized71Ga NMR spectroscopy makes it possible to take an in-depth look into the gallium chemistry in a new light. In particular, the key participation of GaHal4-anions in the occurring transformations has been established.
- Novikov, Roman A.,Denisov, Dmitry A.,Potapov, Konstantin V.,Tkachev, Yaroslav V.,Shulishov, Evgeny V.,Tomilov, Yury V.
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supporting information
p. 14381 - 14390
(2018/10/24)
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- Synthesis of (±)-Pregabalin by Utilizing a Three-Step Sequential-Flow System with Heterogeneous Catalysts
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(±)-Pregabalin, a γ-amino acid derivative, has been synthesized by utilizing flow methods. A three-step sequential-flow reaction starting from commercial isovaleraldehyde and methyl malonate proceeded smoothly with heterogeneous catalysts to afford the precursor of pregabalin in yields of 75–100 %, and a space-time yield of 52.2 g/L d was reached. In addition, a heterogeneous catalyst for the Knoevenagel reactions of aldehydes with malonates, which is the first step of the synthesis, has been developed. Pregabalin was finally obtained by acid-catalyzed hydrolysis of the precursor followed by neutralization.
- Ishitani, Haruro,Kanai, Kan,Saito, Yuki,Tsubogo, Tetsu,Kobayashi, Shū
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supporting information
p. 6491 - 6494
(2017/10/18)
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- Scandium(III) Trifluoromethanesulfonate Catalyzed Selective Reactions of Donor–Acceptor Cyclopropanes with 1,1-Diphenylethanols: An Approach to Polysubstituted Olefins
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An unexpected synthetic approach to polysubstituted olefins through the scandium(III) trifluoromethanesulfonate catalyzed ring-opening reaction of donor–acceptor cyclopropanes with 1,1-diphenylethanols was developed. The reactions, which are experimentally easy to handle, feature tolerance of various functional groups and mild reaction conditions. On the basis of experimental evidence, a plausible mechanism was also proposed.
- Zhu, Xiaoyan,Hong, Gang,Hu, Chen,Wu, Shengying,Wang, Limin
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supporting information
p. 1547 - 1551
(2017/04/01)
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- Cascade One-Pot Synthesis of Indanone-Fused Cyclopentanes from the Reaction of Donor-Acceptor Cyclopropanes and Enynals via a Sequential Hydrolysis/Knoevenagel Condensation/[3+2] Cycloaddition
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A cascade reaction of donor-acceptor cyclopropanes with enynals to construct indanone-fused cyclopentanes via a sequential hydrolysis/Knoevenagel condensation/[3+2] cycloaddition is reported. The desired indanone-fused cyclopentanes were obtained in good yields. This method features mild reaction conditions and broad substrate scope, which render it very appealing to chemists for the synthesis of complex molecules containing an indanone-fused cyclopentane moiety. Moreover, the products could be further converted into compounds with different functional groups through the well-known transformations. (Figure presented.).
- Zhang, Jiantao,Jiang, Huanfeng,Zhu, Shifa
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supporting information
p. 2924 - 2930
(2017/09/08)
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- Construction of 1-pyrroline skeletons by Lewis acid-mediated conjugate addition of vinyl azides
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Lewis acid-mediated conjugate addition of vinyl azides to electron-deficient alkenes led to the efficient construction of 1-pyrroline skeletons. The reactions of vinyl azides with 3-alkylidene-2-oxoindolines afford 3′,4′-dihydrospiro[indoline-3,2′-pyrrol]-2-ones in a diastereoselective fashion, whereas those with dimethyl 2-alkylidenemalonates provide 4,5-dihydro-3H-pyrroles.
- Zhu, Xu,Chiba, Shunsuke
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supporting information
p. 2473 - 2476
(2016/02/18)
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- A bionic aqueous heterogeneous catalytic system catalytic aromatic aldehydes with malonic acid diester method of the condensation reaction between
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The invention discloses a method for catalyzing the condensation reaction between aromatic aldehyde and malonic diester with a bionic water-containing heterogeneous catalytic system. According to the method, aromatic aldehyde and malonic diester are adopt
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Paragraph 0070; 0074; 0078
(2018/01/19)
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- A general post-synthetic modification approach of amino-tagged metal-organic frameworks to access efficient catalysts for the Knoevenagel condensation reaction
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In this manuscript, four common transition-metal derived metal-organic frameworks have been extensively investigated as heterogeneous catalyst supports for Knoevenagel condensation reactions. A simple post-synthetic modification strategy was employed for the rapid and facile introduction of a primary alkyl amino group. The resulting novel MOF-RNH2 catalysts showed greatly enhanced Knoevenagel condensation reactivities towards a variety of aldehyde electrophiles. IRMOF-3 proved to be an unsuitable heterogeneous catalyst support due to its fragile nature upon treatment with bases. The novel zirconium based UiO-66-NH-RNH2 and chromium based Cr-MIL-101-NH-RNH2 materials showed excellent catalytic reactivities, while being highly convenient to synthesize. The basic catalytic activity was further extended to the Henry reaction, and excellent catalytic reactivity was achieved. The size-selectivity was also studied to show that the Knoevenagel condensation occurred inside of the porous structure of the MOF catalyst. The recycling properties of zirconium, aluminum and chromium derived MOFs were evaluated and zirconium based UiO-66 and chromium based Cr-MIL-101 showed excellent catalytic efficiency after five reaction cycles.
- Luan, Yi,Qi, Yue,Gao, Hongyi,Andriamitantsoa, Radoelizo S.,Zheng, Nannan,Wang, Ge
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supporting information
p. 17320 - 17331
(2015/08/24)
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- Amines functionalized C60 as solid base catalysts for Knoevenagel condensation with high activity and stability
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Four kinds of amines functionalized C60 were prepared through an amination reaction of C60 with organic amines. Their surface structures and basic properties were studied by Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) with CO2 as the probe molecule. When used as solid base catalysts, N-aminoethylpiperazine functionalized C60 (C60-AEP) showed the best catalytic activity in the Knoevenagel condensation reaction due to the highest basic strength. In addition, the C60-AEP catalyst also showed impressive catalytic stability. All these features endowed C60-AEP with characteristics of both homogeneous and heterogeneous catalysts. More interestingly, chiral l-lysine functionalized C60 (C60-L-L) can be used for asymmetric intermolecular aldol reactions.
- Sun, Yongbin,Cao, Changyan,Huang, Peipei,Yang, Shuliang,Song, Weiguo
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p. 86082 - 86087
(2015/11/03)
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- Efficient synthesis of β-aryl-γ-lactams and their resolution with (S)-Naproxen: Preparation of (R)- and (S)-Baclofen
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An efficient synthesis of enantiomerically-pure β-aryl-γ-lactams is described. The principal feature of this synthesis is the practical resolution of β-aryl-γ-lactams with (S)-Naproxen. The procedure is based on the Michael addition of nitromethane to benzylidenemalonates, which was easily obtained, followed by the reduction of the γ-nitroester in the presence of Raney nickel and the subsequent saponification/decarboxylation reaction. The utility of this methodology was highlighted by the preparation of enantiomerically-pure (R)- and (S)-Baclofen hydrochloride.
- Montoya-Balbás, Iris J.,Valentín-Guevara, Berenice,López-Mendoza, Estefanía,Linzaga-Elizalde, Irma,Ordo?ez, Mario,Román-Bravo, Perla
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p. 22028 - 22043
(2016/01/25)
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- Tetrahydro-1,3-oxazepines via Intramolecular Amination of Cyclopropylmethyl Cation
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An efficient synthesis of tetrahydro-1,3-oxazepines was developed involving the regioselective intramolecular amination of cyclopropylmethyl cation. The cation was generated by the abstraction of one imidate group in bis-imidate bearing a carbocation-stabilizing substituent. Using 1,1,2,3-tetrasubstituted cyclopropane substrates, highly diastereoselective intramolecular amination to trans-tetrahydro-1,3-oxazepines was achieved. The resulting tetrahydro-1,3-oxazepines were transformed to the homoallylamine derivatives in high yields.
- Skvorcova, Marija,Grigorjeva, Liene,Jirgensons, Aigars
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supporting information
p. 2902 - 2904
(2015/06/30)
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- Triflic Acid Catalyzed Formal [3 + 2] Cycloaddition of Donor-Acceptor Oxiranes and Nitriles: A Facile Access to 3-Oxazolines
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A TfOH-catalyzed chemoselective [3 + 2] cycloaddition of donor-acceptor oxiranes and nitriles is described. This reaction provides an efficient and practical method for the preparation of useful 3-oxazolines in good to excellent yields (up to 99%).
- Zhou, Hai,Zeng, Xiaofei,Ding, Liyuan,Xie, Yan,Zhong, Guofu
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supporting information
p. 2385 - 2387
(2015/05/27)
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- Synthesis of 3-Oxazolines via SnCl4-Promoted Formal [3+2] Cycloaddition of Donor-Acceptor Oxiranes and Nitriles
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A novel SnCl4-promoted formal [3+2] cycloaddition of donor-acceptor oxiranes and nitriles via chemoselective C-C bond breakage was developed. This reaction provides an efficient and practical method for the preparation of 3-oxazolines in good yields (up to 89%).
- Zhou, Hai,Zeng, Xiaofei,Xie, Yan,Zhong, Guofu
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supporting information
p. 1693 - 1696
(2015/07/20)
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- Reductive alkylation of active methylene compounds with carbonyl derivatives, calcium hydride and a heterogeneous catalyst
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A one-pot two-step reaction (Knoevenagel condensation - reduction of the double bond) has been developed using calcium hydride as a reductant in the presence of a supported noble metal catalyst. The reaction between carbonyl compounds and active methylene
- Guyon, Carole,Duclos, Marie-Christine,Sutter, Marc,Métay, Estelle,Lemaire, Marc
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p. 7067 - 7075
(2015/06/25)
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- Indium(III)-catalyzed knoevenagel condensation of aldehydes and activated methylenes using acetic anhydride as a promoter
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The combination of a catalytic amount of InCl3 and acetic anhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation of a geminal diacetate intermediate, which was generated in situ from an aldehyde and an acid anhydride with the assistance of an indium catalyst.
- Ogiwara, Yohei,Takahashi, Keita,Kitazawa, Takefumi,Sakai, Norio
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p. 3101 - 3110
(2015/03/30)
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- A new type of donor-acceptor cyclopropane reactivity: The generation of formal 1,2- and 1,4-dipoles
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A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3, they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles due to migration of positive charge from the benzyl center. This type of reactivity has been demonstrated for new reactions, namely, cyclodimerizations of donor-acceptor cyclopropanes that occur as [2+2]-, [3+2]-, [4+2]-, [5+2]-, [4+3]-, and [5+4]-annulations. The [4+2]-annulation of 2-arylcyclopropane-1,1-dicarboxylates to give polysubstituted 2-aryltetralins has been developed in a preparative version that provides exceedingly high regio- and diastereoselectivity and high yields. The strategy for selective hetero-combination of donor-acceptor cyclopropanes was also been developed. The mechanisms of the discovered reactions involving the formation of a comparatively stable 1,2-ylide intermediate have been studied. Old ring, new reactivity: A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3, they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles owing to the migration of positive charge from the benzyl center.
- Novikov, Roman A.,Tarasova, Anna V.,Korolev, Victor A.,Timofeev, Vladimir P.,Tomilov, Yury V.
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supporting information
p. 3187 - 3191
(2014/04/03)
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- TiCl4 promoted formal [3 + 3] cycloaddition of cyclopropane 1,1-diesters with azides: Synthesis of highly functionalized triazinines and azetidines
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A TiCl4 promoted formal [3 + 3] cycloaddition of cyclopropane 1,1-diesters with azides has been developed for the synthesis of highly functionalized triazinines. Both stoichiometric and substoichiometric versions of this reaction were accomplished dependent on the choice of solvent. It is noteworthy that the corresponding products could be easily converted to biologically important azetidines by simple thermolysis.
- Zhang, Huan-Huan,Luo, Yong-Chun,Wang, Hua-Peng,Chen, Wei,Xu, Peng-Fei
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supporting information
p. 4896 - 4899
(2015/04/27)
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- Lithium perchlorate-, acetic anhydride-, and triphenylphosphine-assisted multicomponent syntheses of 4-unsubstituted 2,5-dioxooctahydroquinoline-3- carboxylates and 3-carbonitriles
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Lithium perchlorate and acetic anhydride were the key additives for the multi-component reaction between 3-aminocyclohex-2-enones, formaldehyde, and malonates yielding adducts that were annulated under acidic conditions to afford bicyclic 2,5-dioxooctahydroquinoline-3-carboxylates. When methyl cyanoacetate was subjected to the same reaction conditions in the presence of a catalytic amount of triphenylphosphine, the bicyclic 2,5-dioxooctahydroquinoline-3- carbonitriles were obtained in a one-flask reaction.
- Gu, Xingxian,Georg, Gunda I.
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p. 9406 - 9416
(2013/10/08)
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- Organocatalytic knoevenagel condensations by means of carbamic acid ammonium salts
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The Knoevenagel condensation between an active methylene compound and an aromatic aldehyde with a carbamic acid ammonium salt used as an organocatalyst gave the desired Knoevenagel products in up to 98% yield. The reaction occurred at rt and in a short reaction time under solvent-free conditions. In addition, no extraction, wash, or chromatography steps were needed to obtain a high-purity Knoevenagel product.
- Mase, Nobuyuki,Horibe, Takuya
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supporting information
p. 1854 - 1857
(2013/06/04)
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- Tin oxide nanoparticles (NP-SnO2): Preparation, characterization and their catalytic application in the Knoevenagel condensation
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Tin oxide (SnO2) nanoparticles were synthesized by modified thermal decomposition process. Taguchi analysis was used and three important synthetic factors, molar concentration ratio of [NaNO3]/[SnCl 4], temperature and tim
- Sharghi, Hashem,Ebrahimpourmoghaddam, Sakineh,Memarzadeh, Raheleh,Javadpour, Sirous
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p. 141 - 149
(2013/02/25)
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- Substituted 3(2H)-Furanones by a tandem michael addition/palladium- catalyzed ring-closing protocol
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A novel palladium-catalyzed route for the synthesis of substituted 3(2H)-furanones from activated alkenes and 4-chloroacetoacetate was developed. The first step of the tandem reaction is the Michael addition of an acetoacetate to the alkene followed by palladium-catalyzed ring closure of the adduct to form the furanone. The reaction was extended to a number of substituted alkenes, and the corresponding substituted 3(2H)-furanones were obtained in good to excellent yields. Copyright
- John, Jubi,Hopf, Henning
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supporting information
p. 841 - 845
(2013/03/14)
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- Total synthesis of cladoniamide G
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The total synthesis of cladoniamide G, a cytotoxic compound against MCF-7 breast cancer cells (10 μg/mL), was accomplished. Key steps in the sequence include oxidative dimerization of 3-acetoxy-5-chloroindole and a tandem process incorporating three steps
- Loosley, Benjamin C.,Andersen, Raymond J.,Dake, Gregory R.
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p. 1152 - 1154
(2013/04/10)
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- Nickel(ii)-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine imines with alkylidene malonates
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We demonstrated an asymmetric 1,3-dipolar cycloaddition of azomethine betaines with alkylidene malonates by using a chiral N,N'-dioxide- NiII complex as a catalyst. Both aromatic- and aliphatic-substituted alkylidene malonates were found to be suitable for the reaction. A range of transpyrazolone derivatives was exclusively obtained with excellent yields (up to 99% yield) and good enantioselectivities (up to 97% ee) under mild reaction conditions. The reaction could be carried out on a gram scale with the good results being maintained. Control experiments were performed to elucidate the specific diastereoselectivity of the reaction. The formation of single trans isomers was dominated by secondary orbital interactions between the ester groups of the dipolarophile and the azomethine imine. On the basis of the experimental results and previous reports, a possible catalytic model was assumed.
- Li, Jiangting,Lian, Xiangjin,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 5134 - 5140
(2013/07/05)
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- Iodine-promoted synthesis of 3-arylindolizine-1-carboxylates from 2-(2-nitro-1-arylethyl)malonates and pyridine
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An efficient and straightforward one-pot synthetic protocol has been developed for the synthesis of 3-arylindolizine- 1-carboxylates via 1,3-dipolar annulation of 2-(2-nitro-1-arylethyl)malonates with pyridine and subsequent aromatisation in the presence of molecular iodine. The structure of methyl 3-(4-methoxyphenyl)indolizine-1-carboxylate (2a) and methyl 3-iodo-2-(4- nitrophenyl)indolizine-1-carboxylate (2f) was further confirmed by X-ray single crystal analysis. Website
- Li, Yun,Zhou, Zhengquan,Ye, Weijian,Liu, Juanjuan,Yao, Juan,Wang, Cunde
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p. 526 - 530
(2013/10/22)
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- Lewis acid mediated (3 + 2) cycloadditions of donor-acceptor cyclopropanes with heterocumulenes
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Isocyanates, isothiocyanates, and carbodiimides are effective substrates in (3 + 2) cycloadditions with donor-acceptor cyclopropanes for the synthesis of five-membered heterocycles. These reactions exhibit a broad substrate scope, high yields, and well-defined chemoselectivity. Discussed herein are the implications of Lewis acid choice on the stereochemical outcome and the reaction mechanism.
- Goldberg, Alexander F. G.,O'Connor, Nicholas R.,Craig, Robert A.,Stoltz, Brian M.
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supporting information
p. 5314 - 5317,4
(2012/12/12)
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- Lewis acid mediated (3 + 2) cycloadditions of donor-acceptor cyclopropanes with heterocumulenes
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Isocyanates, isothiocyanates, and carbodiimides are effective substrates in (3 + 2) cycloadditions with donor-acceptor cyclopropanes for the synthesis of five-membered heterocycles. These reactions exhibit a broad substrate scope, high yields, and well-defined chemoselectivity. Discussed herein are the implications of Lewis acid choice on the stereochemical outcome and the reaction mechanism.
- Goldberg, Alexander F. G.,O'Connor, Nicholas R.,Craig, Robert A.,Stoltz, Brian M.
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supporting information
p. 5314 - 5317
(2013/01/15)
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- Transition metal and hydrogen bond donor hybrids: Catalysts for the activation of alkylidene malonates
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Palladium ureaka! Urea palladacycles are introduced to activate alkylidene malonates for nucleophilic attack. The strategic incorporation of palladium on a urea scaffold give rise to urea catalysts with enhanced reactivity when compared to conventional ur
- Nickerson, David M.,Mattson, Anita E.
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supporting information; experimental part
p. 8310 - 8314
(2012/08/13)
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