- Humic substances as catalysts m condensation reactions
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Humic substances (HS) demonstrate appreciable impact on the rate of the condensation reactions as shown in the example of the reaction between hydrazine and 4-(dimethylamino)-benzaldhyde in an aquatic environment. The catalytic activity of HS has also been demonstrated in Knoevenagel and Claisen-Schmidt reactions for condensation of carbonyl compounds with CH acids. The aquatic fulvic acids are the most active in these reactions. The velocity of the studied reactions also depends on pH, temperature, the concentration and origin of HS used. A possible micellar and acid-base catalysis mechanism in aquatic media has been suggested.
- Klavins, Maris,Dipane, Judite,Babre, Kristine
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- Porous Boron Nitride as a Weak Solid Base Catalyst
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Porous boron nitride was synthesized by pyrolysis from boric acid and urea mixed in varying molar ratios. The boron nitride prepared had high surface areas ranging from 376 to 647 m2 g?1 with both microporous and mesoporous structures. The sample prepared with a urea-to-boric acid molar ratio of 5 exhibited the highest pore volume with the highest surface area of mesopores. Boron-K edge X-ray absorption fine structure spectroscopy revealed that the surface structure consisted of BN3 sites along with BN2O, BNO2, and BO3 sites. Fourier transform infrared (FTIR) spectroscopy indicated the formation of amino and hydroxyl groups on the surface. Analysis using color indicator reagents and deuterated chloroform-adsorbed FTIR results indicated that the porous boron nitride had very weak base sites of strength +7.2>H?≥+6.3. Porous boron nitride exhibited a high activity for the nitroaldol reaction with a high selectivity for nitroalkene (>97 %). A good correlation was observed between the catalytic activity of the boron nitride catalysts and their porous structures.
- Nakamura, Shohei,Takagaki, Atsushi,Watanabe, Motonori,Yamada, Kanta,Yoshida, Masaaki,Ishihara, Tatsumi
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- Water-controlled nitro-oximation of alkenes under catalyst-free conditions
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A convenient and precise nitration and oximation of alkenes with tert-butyl nitrite has been reported, yielding α-nitro ketoximes in satisfactory yields with broad substrate generality and excellent stereoselectivity under mild conditions. Experiments indicate that tert-butyl nitrite serves as both NO and NO2 sources and water plays a key role in this difunctionalization reaction.
- Tang, Lin,Yang, Zhen,Chang, Xueping,Zou, Guodong,Zhou, Yuqiang,Rao, Weihao,Ma, Xiantao,Zhao, Geng
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- Cu(II) homogeneous and heterogeneous catalysts for the asymmetric Henry reaction
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New homogeneous Cu(II) complexes have been prepared, fully characterised and tested for the asymmetric Henry reaction. Heterogeneous Cu(II) catalysts have been synthesised for comparison purposes.
- Jones, Matthew D.,Cooper, Christine J.,Mahon, Mary F.,Raithby, Paul. R.,Apperley, David,Wolowska, Joanna,Collison, David
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- Diastereoselective synthesis of polysubstituted cyclopentanols and cyclopentenes containing stereogenic centers via domino Michael/cyclization reaction
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A highly efficient domino Michael/cyclization reaction was developed for the synthesis of cyclopentanols and cyclopentenes with four and three stereogenic centers that were generated in one-pot reaction conditions with high diastereoselectivity. The reactions proceeded through a one-pot three-component reaction of β-nitrostyrenes, malononitrile and phenacyl bromide derivatives in basic media at room temperature.
- Ahadi,Naghdiani,Balalaie,Rominger
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- A simple O-sulfated thiohydroximate molecule to be the first micromolar range myrosinase inhibitor
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New non-hydrolyzable analogues of glucosinolates have been prepared. Myrosinase inhibition was observed with modified aglycon moieties, even bulky phenothiazine analogue 6 gave reasonable inhibition. The simplest structure 8 derived from dimethylaminoethanethiol has shown to be the most potent inhibitor with an IC50 of 3.32 μM.
- Cerniauskaite, Deimante,Gallienne, Estelle,Karciauskaite, Henreta,Farinha, Andrea S.F.,Rousseau, Jolanta,Armand, Sylvie,Tatibou?t, Arnaud,Sackus, Algirdas,Rollin, Patrick
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- Direct synthesis and application of bridged diamino-functionalized periodic mesoporous organosilicas with high nitrogen contents
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Bridged diamino-functionalized periodic mesoporous organosilicas [BD-PMO(Et), Et = ethyl] materials were synthesized directly by co-condensation of 2-bis (triethoxysilyl)ethane (BTEE) and 1,4-bis[3-(tirmethoxysilyl)-propyl]ethylenediamino (BTMSEN) under acidic conditions with pluronic triblock copolymer P123 as a template. The nitrogen content in BD-PMO(Et) could be adjusted up to 40% without disturbing the ordered mesoporous structure. These materials were proved to be effective heterogeneous catalysts for the liquid-phase reactions such as Knoevenagel and Henry condensations as well as in the intermolecular cross-double-Michael addition reaction between α-methyl-β-nitrostyrene and α, β-unsaturated ketone. They exhibited comparable catalytic activities with homogeneous catalyst piperazine and can be reused for several times without any negative environmental impact.
- Zhu, Feng-Xia,Zhao, Pu-Su,Sun, Xiao-Jun,An, Li-Tao,Deng, Yong,Wu, Jia-Min
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- Mild and Regioselective Three-component Heteroarylation-Nitration of Alkenes with Imidazo[1,2-a]pyridines and tert-Butyl Nitrite
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An efficient and regioselective three-component heteroarylation-nitration of alkenes with imidazo[1,2-a]pyridines and tert-butyl nitrite has been developed. The process tolerants a variety of functional groups under mild conditions in the absence of catalysts and additives to give nitro functionalized imidazo[1,2-a]pyridine derivatives in moderate to good yields. The reaction is also applicable for some other aza-heterocycles. (Figure presented.).
- Liu, Ping,Sun, Peipei,Xie, Shentong,Zhang, Jie
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- Preparation and synergetic catalytic effects of amino-functionalized MCM-41 catalysts
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Four amine functionalized mesoporous catalysts were synthesized by grafting primary, dualistic and two secondary amines onto the channel walls of mesoporous silica, MCM-41. We examined the effects of organoamine loading amount on the acid-base synergism of the catalysts in the self-condensation reaction of n-butanal, a Knoevenagel condensation and a Henry reaction. We observed the balance of the amine and residual silanol amounts is crucial to the catalytic performances of the functionalized mesoporous catalysts. An optimum organoamine loading amount exists, which is dependent on the organoamine type. There is little difference in the optimum organoamine loading amount between different reactions. The secondary organoamine functionalized MCM-41 exhibits the best catalytic performance in the experimental range.
- Lang, Wanzhong,Su, Bo,Guo, Yajun,Chu, Lianfeng
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- Facile and efficient michael addition of indole to nitroolefins catalyzed by zn(OAc)22H2O
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The Zn(OAc)22H2O-catalyed Michael addition reaction of indole to electron-deficient nitroolefins to afford the corresponding adducts in good to excellent yields with high selectivity is reported.
- Ji, Xiang,Tong, Haibo,Yuan, Yu
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- Side-Chain Nitration of Styrene and Para-Substituted Derivatives with a Combination of Nitrogen Dioxide and Ozone
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The side-chain nitration of styrene and four para-substituted derivatives 1 with a combination of nitrogen dioxide and ozone has been investigated as part of our continued effort to define the scope of applicability of this new nitration methodology (kyodai nitration). Styrene and derivatives underwent a smooth addition reaction across the olefinic bond in dichloromethane at -20°C, affording the corresponding isomeric nitro-nitrato adducts 2 and 3 in excellent combined yield. 1H-NMR data were collected for all possible nitro-nitrato adducts of styrene and derivatives. The mechanism of the formation of these addition products is discussed in terms of the reversible addition of nitrogen dioxide to form unstable nitroso-nitrates 9 and 10 followed by rapid oxidation of these to the corresponding nitro-nitrates 2 and 3.
- Suzuki, Hitomi,Mori, Tadashi
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- Zeolite Y-assisted nitration of aromatic and heterocyclic compounds and decarboxylative nitration of α,β-unsaturated acids under non-conventional conditions
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Zeolite Y was found to be an efficient catalyst for a facile nitration of aromatic compounds with acetonitrile as the solvent in the presence of small amounts of HNO3 at room temperature. The reactions afforded mono-nitro derivatives of aromatic compounds in about three hours under stirred conditions with high yields and regioselectivity. The reaction times drastically reduced to about 20 min under sonication and to about 20 s under microwave irradiation. Zeolite is recovered after completion of the reaction and recycled for three to four times without any problem. The approach is particularly appropriate for the conversion of unsaturated cinnamic acids into nitrostyrenes.
- Sudhakar Chary,Rajanna,Krishnaiah,Srinivas
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- Metal ion exchange in Prussian blue analogues: Cu(ii)-exchanged Zn-Co PBAs as highly selective catalysts for A3 coupling
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The occurrence of metal ion exchange in Zn3[Co(CN)6]2 and Cu3[Co(CN)6]2 Prussian blue analogues (Zn-Co and Cu-Co PBAs) was demonstrated for the first time. While Cu(ii) ion exchange easily occurs in Zn-Co PBA, the exchange of Cu(ii) atoms in Cu-Co PBA by Zn(ii) proved to be more difficult. At low to medium Cu(ii) loadings, the catalytic activity of the exchanged PBAs for the A3 coupling reaction of benzaldehyde, piperidine and phenylacetylene was higher than that of the bimetallic PBAs and that of multi metal PBAs of similar composition prepared by co-precipitation. This result showcases the benefits of the ion exchange process as a preparation method of PBA catalysts, since it is believed to lead to the incorporation of the desired metal in a more accessible position for reactant molecules. At higher Cu(ii) loadings, ion exchange with Cu(CH3COO)2·H2O also resulted in co-incorporation of CH3COO-. This incorporation considerably boosted the catalytic activity of the PBAs by providing a basic function that facilitates the C-H activation of phenylacetylene. The most active of the studied PBAs, catallytically outperforms other Cu(ii) based A3 coupling catalysts and completely suppresses the activity for the homocoupling of phenylacetylene, even under oxidative conditions. Furthermore, the basicity of the PBAs was investigated in the nitroaldol (Henry) reaction, where a clear effect of the presence of CH3COO- was observed. The CH3COO- containing PBAs exhibited an activity three times higher than the rest of the PBAs. The presence of the basic CH3COO- groups represents the first case of basic functionalization of PBAs.
- Marquez, Carlos,Cirujano, Francisco G.,Smolders, Simon,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk,De Baerdemaeker, Trees
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- Access to C5-Alkylated Indolines/Indoles via Michael-Type Friedel-Crafts Alkylation Using Aryl-Nitroolefins
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A straightforward synthetic route toward C5-alkylated indolines/indoles has been developed. The strategy is composed of Zn(OTf)2-catalyzed Friedel-Crafts alkylation of N-benzylindolines with nitroolefins, and a series of diverse indolines was first obtained in up to 99% yield. This reaction provides a direct and practical route to a variety of the C5-alkylated indolines which were also utilized for accessing corresponding indoles. Indoline derivatives with free NH groups could be obtained through an N-deprotection reaction. Moreover, the primary alkyl nitro groups in both indolines and indoles are amenable to further synthetic elaborations, thereby broadening the diversity of the products.
- Ertugrul, Berrak,Kilic, Haydar,Lafzi, Farrokh,Saracoglu, Nurullah
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- A novel tandem sequence to pyrrole syntheses by 5-endo-dig cyclization of 1,3-enynes with amines
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The synthesis of pentasubstituted pyrroles has been described using molecular iodine from 1,3-enynes and amines via a sequential tandem aza-Michael addition, iodocyclization, and oxidative aromatization. The protocol is simple and efficient to afford the target products at ambient conditions.
- Bharathiraja, Ganesan,Sakthivel, Sekarpandi,Sengoden, Mani,Punniyamurthy, Tharmalingam
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- Iodine catalyzed one-pot synthesis of highly substituted N-methyl pyrroles via [3 + 2] annulation and their in vitro evaluation as antibacterial agents
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A new class of highly substituted pyrroles have been synthesized via a simple, fast, and efficient method using environmentally friendly iodine catalyzed [3 + 2] annulation. N-Methyl-N-[(E)-1-(methylsulfanyl)-2-nitro-1-ethenyl]amine (NMSM) 1 and β-nitrostyrenes 3 underwent cycloaddition to afford the desired products 4 in excellent yields under solvent and metal free conditions. All the pyrrole derivatives were evaluated for their in vitro anti-bacterial activity. Among the synthesized pyrrole derivatives, 4b, 4c, 4e, 4g, 4i, 4j, 4l, 4m and 4n displayed good inhibitory properties against a panel of Gram positive and negative infectious pathogens.
- Balachandra, Biguvu,Shanmugam, Sivakumar,Muneeswaran, Thillaichidambaram,Ramakritinan, Muthiah
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- Kinetic and Mechanistic Examination of Acid-Base Bifunctional Aminosilica Catalysts in Aldol and Nitroaldol Condensations
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The kinetic and mechanistic understanding of cooperatively catalyzed aldol and nitroaldol condensations is probed using a series of mesoporous silicas functionalized with aminosilanes to provide bifunctional acid-base character. Mechanistically, a Hammett analysis is performed to determine the effects of electron-donating and electron-withdrawing groups of para-substituted benzaldehyde derivatives on the catalytic activity of each condensation reaction. This information is also used to discuss the validity of previously proposed catalytic mechanisms and to propose a revised mechanism with plausible reaction intermediates. For both reactions, electron-withdrawing groups increase the observed rates of reaction, though resonance effects play an important, yet subtle, role in the nitroaldol condensation, in which a p-methoxy electron-donating group is also able to stabilize the proposed carbocation intermediate. Additionally, activation energies and pre-exponential factors are calculated via the Arrhenius analysis of two catalysts with similar amine loadings: one catalyst had silanols available for cooperative interactions (acid-base catalysis), while the other was treated with a silanol-capping reagent to prevent such cooperativity (base-only catalysis). The values obtained for activation energies and pre-exponential factors in each reaction are discussed in the context of the proposed mechanisms and the importance of cooperative interactions in each reaction. The catalytic activity decreases for all reactions when the silanols are capped with trimethylsilyl groups, and higher temperatures are required to make accurate rate measurements, emphasizing the vital role the weakly acidic silanols play in the catalytic cycles. The results indicate that loss of acid sites is more detrimental to the catalytic activity of the aldol condensation than the nitroaldol condensation, as evidenced by the significant decrease in the pre-exponential factor for the aldol condensation when silanols are unavailable for cooperative interactions. Cooperative catalysis is evidenced by significant changes in the pre-exponential factor, rather than the activation energy for the aldol condensation.
- Collier, Virginia E.,Ellebracht, Nathan C.,Lindy, George I.,Moschetta, Eric G.,Jones, Christopher W.
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- Highly efficient iridium-catalyzed asymmetric hydrogenation of β-acylamino nitroolefins
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The first highly efficient Ir-catalyzed enantioselective hydrogenation of β-acylamino nitroolefins is reported. This reaction provides straightforward access to chiral β-amino nitroalkanes in high yields and excellent enantioselectivities (up to >99.9% ee) catalyzed by an Ir-(R,R)-f-spiroPhos complex. This journal is
- Yan, Qiaozhi,Liu, Man,Kong, Duanyang,Zi, Guofu,Hou, Guohua
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- Yolk-shell-structured mesoporous silica: A bifunctional catalyst for nitroaldol-Michael one-pot cascade reaction
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Great interest in heterogeneous asymmetric catalysis has focused on obtaining an enantioselective cascade reaction through a controllable active site-isolated heterogeneous catalyst. Herein, we utilize a yolk-shell-structured mesoporous silica and assemble an active site-isolated bifunctional heterogeneous catalyst, where chiral cinchonine-based squaramide molecules are anchored within a silicate channel as an outer shell while amine-functionalities are entrapped onto a silicate yolk as an inner core. Structural analyses and characterizations of the heterogeneous catalyst reveal its well-defined single-site chiral active species within its silicate network. Electron microscopy confirms the yolk-shell-structured mesoporous material. As presented in this study, as a bifunctional heterogeneous catalyst, it enables an efficiently nitroaldol-Michael cascade reaction to conduct the three-component coupling of nitromethane, aldehyde and acetylacetone into various chiral diones with high yields and up to 99% enantioselectivities in a one-pot process. As expected, this active site-isolated catalyst not only enhances the catalytic selectivity of the first-step nitroaldol condensation, but also keeps the enantioselectivity of the second-step Michael addition. Moreover, the heterogeneous catalyst can be also recovered easily and recycled repeatedly, making it an interesting feature in a three-component organic transformation.
- An, Juzeng,Cheng, Tanyu,Xiong, Xi,Wu, Liang,Han, Bin,Liu, Guohua
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- Ultrasonic-Assisted Linker Exchange (USALE): A Novel Post-Synthesis Method for Controlling the Functionality, Porosity, and Morphology of MOFs
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The introduction of organic ligands into metal–organic frameworks (MOFs) with a specific topology and that cannot be attained by direct synthesis is a big challenge. To meet this challenge, different ligand exchange/incorporation methods have been employed. Here, a new method, called ultrasonic-assisted linker exchange (USALE), has been developed to overcome the above-mentioned problems. USALE is a novel method for ligand exchange based on the use of ultrasonic waves. The temperature and pressure caused by the USALE method in microscopic zones are so intense that the linker exchange process is much faster than with other methods. In addition to saving time during synthesis, the use of the USALE method leads to a higher surface area and pore volume compared with other methods such as solvent-assisted linker exchange (SALE). In this way, improved gas adsorption capacity has been achieved for daughter frameworks synthesized by the USALE method. By using the USALE method, we have transformed a nonporous and easy-to-synthesize TMU framework ([Zn(OBA)(BPDB)0.5]n?2DMF (TMU-4), in which H2OBA=4,4′-oxybis(benzoic acid) and BPDB=1,4-di(4-pyridyl)-2,3-diaza-1,3-butadiene) into another porous framework ([Zn(OBA)(H2DPT)0.5]n?DMF (TMU-34), in which H2DPT=3,6-di(4-pyridyl)-1,4-dihydro-1,2,4,5-tetrazine) that otherwise requires a relatively long time to synthesize. In addition to reducing the synthesis time for TMU-34 (in comparison with both direct sonochemical synthesis and the indirect SALE method), the data obtained revealed that the daughter TMU-34 framework synthesized by the USALE method has a higher surface area and accessible pore volume than TMU-34 frameworks synthesized by SALE and direct methods. The application of SALE-TMU-34 and USALE-TMU-34 in a catalytic Henry condensation reaction and Congo Red adsorption experiments showed that the higher porosity of USALE-TMU-34 leads to a higher turn-over frequency and saturation capacity compared with SALE-TMU-34.
- Razavi, Sayed Ali Akbar,Morsali, Ali
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- Continuous-flow synthesis using a column reactor packed with heterogeneous catalysts: A convenient production of nitroolefins by using amino-functionalized silicagel
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A continuous-flow synthesis of β-nitroolefins by using heterogeneous base catalysts has been developed. Although the use of an excess amount of nitro-donor such as nitromethane is required in conventional methods, nearly equimolar amounts of nitro-donors and carbonyl compounds are sufficient for high-yielding production of nitroolefins. Catalysts for this flow protocol are inexpensive and abundant, and high durability and high productivity were also realized by using an appropriate second support.
- Ishitani, Haruro,Furiya, Yuichi,Kobayashi, Shū
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- Catalyst-free sulfa-Michael addition of pyrimidine-2-thiol to nitroolefins
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Catalyst-free sulfa-Michael addition of pyrimidine-2-thiol to nitroolefins is described. A series of 2-((2-nitro-1-arylethyl)thio)pyrimidines were efficiently synthesized. The protocol has advantages of wide range of substituents tolerance, no catalyst, additives and bases, mild condition, and high yield. The method can also extend to gram scale.
- Li, Zheng,Song, Geyang,He, Jiaojiao,Du, Yan,Yang, Jingya
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- Charge-transfer interactions: An efficient tool for recycling bis(oxazoline)-copper complexes in asymmetric henry reactions
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An anthracenyl-modified chiral bis(oxazoline) copper complex has been demonstrated to efficiently promote nitroaldol reactions between structurally varying aldehydes and nitromethane or nitroethane. The catalyst was recovered through formation of a charge transfer complex between the chiral ligand and trinitrofluorenone and its subsequent precipitation with pentane. The efficiency of this procedure was proved through several consecutive catalytic cycles that allowed the sturdy formation of the expected product with a high enantioselectivity. The catalyst′s stability was also put to the test in an original multi-substrate procedure. Following the same recovery concept, a new heterogeneous procedure was tested for which trinitrofluorenone was covalently linked to a silica support. Asymmetric heterogeneous catalysis was performed under these conditions as one of the few examples demonstrating the potential catalyst recycling in nitroaldol reactions through reversible, non-covalent interactions. Copyright
- Didier, Dorian,Magnier-Bouvier, Caroline,Schulz, Emmanuelle
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- The rapid synthesis of β-nitrostyrenes under microwave irradiation without solvent
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The β-nitrostyrenes (3a-l) were prepared by condensation of benzaldehydes with nitromethane in the presence of K2CO3/Al2O3 under microwave irradiation without solvent. They were characterized by IR, 1H-NMR, and elemental analysis.
- Wang, Cunde,Wang, Song
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- Synthesis and catalytic properties of hybrid mesoporous materials assembled from polyhedral and bridged silsesquioxane monomers
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A family of hybrid mesoporous materials with high temperature stability was obtained by the suitable covalent combination of two types of siloxane precursors. Specifically, cubic T8 polyhedral oligomeric (POSS) and aryl bridged silsesquioxane monomers (1,4-bis(triethoxysilyl)benzene, BTEB) play the role of nanobuilders. An optimal molar ratio of the two precursors (5-25 mol % of total silicon content from the BTEB disilane) generated a homogenous, highly accessible, and well-defined mesoporous material with hexagonal symmetry and narrow pore-size distribution. Physicochemical, textural, and spectroscopic analysis corroborated the effective integration and preservation of the two different nanoprecursors, thereby confirming the framework of the mesoporous hybrid materials. A post-synthesis amination treatment allowed the effective incorporation of amino groups onto the aryl linkers, thereby obtaining a stable and recyclable basic catalyst for use in C-C bond-formation processes. Copyright
- Diaz, Urbano,Garcia, Teresa,Velty, Alexandra,Corma, Avelino
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- 3-Nitrochromenes for Second Order Nonlinear Optical Applications
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3-Nitrochromenes bearing various substituents have been prepared by the reaction of substituted salicylaldehydes with nitrostyrenes; some of these compounds have been found to display efficient optical second harmonic generation.
- Ono, Noboru,Sugi, Kiyoshi,Ogawa, Takuji,Aramaki, Shinji
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- Squaramide-Linked Chloramphenicol Base Hybrid Catalysts for the Asymmetric Michael Addition of 2,3-Dihydrobenzofuran-2-carboxylates to Nitroolefins
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An array of hybrid catalysts incorporating a chloramphenicol base moiety linked to another chiral scaffold through a squaramide linker were developed and successfully used in the Michael addition of 2,3-dihydrobenzofuran-2-carboxylates to nitroolefins. Control experiments suggested that the hybrid catalysts were more reactive than nonhybridized bifunctional catalysts, and matching of the chirality between the two scaffolds was crucial for high reactivity and stereoselectivity. These hybrid organocatalysts could be used with a variety of substrates. At a 0.5 mol-% catalyst loading, a range of 2,3-dihydrobenzofuran-2-carboxylates derivatives bearing quaternary and tertiary stereogenic centers were obtained in high yields (up to 98 %) with excellent enantioselectivities (up to 99 % ee) and moderate diastereoselectivities (up to 8:92 dr).
- Yan, Linjie,Huang, Guanxin,Wang, Haifeng,Xiong, Fangjun,Peng, Haihui,Chen, Fener
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- Strong organic bases as building blocks of mesoporous hybrid catalysts for C-C forming bond reactions
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1,8-Bis(tetramethylguanidino)naphthalene (TMGN), a neutral organic base that combines the properties of guanidine and the properties of proton sponges, was used as a building block to produce organic-inorganic silica-based mesoporous hybrids with strong basic properties. The TMGN-based mesoporous hybrids (TMGN/SiO2) were prepared by a sol-gel route working at a neutral pH and low temperatures, which avoided the use of SDAs. TMGN has been modified in order to have two terminal reactive silyl groups able to perform co-condensation with a conventional organosilane (TMOS) used as a silicon source. This synthesis has allowed us to directly introduce the unmodified, functionalized TMGN as part of the walls of the mesoporous silica by a one-pot synthesis. TMGN/SiO2 hybrid materials present excellent catalytic properties for C-C bond forming reactions: Knoevenagel, Henry (nitroaldol), and Claisen-Schmidt condensations. The activity of the hybrid materials is higher than that of the counterpart homogeneous catalyst. The TMGN/SiO2 hybrid catalyst was synthesized using 1,8-bis(tetramethylguanidino)naphthalene (TMGN). It combines the properties of guanidine and of proton sponges. A functionalized TMGN builder was introduced directly into a nonordered mesoporous silica by the NH4F-catalyzed sol-gel route. This catalyst shows good catalytic performances in C-C bond forming reactions. Copyright
- Gianotti, Enrica,Diaz, Urbano,Velty, Alexandra,Corma, Avelino
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- Ethylenediamine-functionalized magnetic Fe3O4@SiO2 nanoparticles: cooperative trifunctional catalysis for selective synthesis of nitroalkenes
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A magnetically separable trifunctional nanocatalyst Fe3O4@SiO2-NH2 was synthesized and characterized by TEM, FT-IR, XRD, TGA, and EA. The designed nanocatalyst was found to be highly active for selective synthesis of nitroalkenes with nitromethane and aromatic aldehyde through cooperative trifunctional catalysis of primary amine, secondary amine and Si-OH groups on the surface of the catalyst. Under the optimized conditions, various representative substrates were extended to obtain the corresponding products in moderate or excellent yields. After the reaction, the trifunctional nanocatalyst was easily recovered and recycled by applying an external magnet. In addition, a possible cooperative trifunctional catalysis mechanism was also proposed.
- Xue, Fengjun,Dong, Yahao,Hu, Peibo,Deng, Yanan,Wei, Yuping
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- Kinetics of Hydroxide and Nitromethide Ion Addition to Substituted β-Nitrostyrenes in Me2SO-Water Mixtures. Solvent Dependence of ?-Donor Substituent Effects and of Intrinsic Rate Constants.
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The kinetics of nucleophilic addition of hydroxide (k1OH) ion and nitromethide (k1NM) ion to phenyl-substituted β-nitrostyrenes (Z = 4-Me2N, 4-MeO, H, 3-Cl, 4-Br, 4-CN, and 4-NO2) have been measured in water, 50percent Me2SO-50percent water, 70percent Me2SO-30percent water ((OH(1-) reaction only), and 90percent Me2SO-10percent water.Equilibrium constants, Keq, for the addition of piperidine to the same β-nitrostyrenes, to form ArCH(NC5H10)CH=NO2(1-) + H(1+), have also been determined.The latter were measured in lieu of the equilibrium constants of hydroxide ion addition (K1OH) which are experimentally difficult to come by; they are used to model the substituent dependence of K1OH.Hammett plots of log k1OH and log k1NM show positive deviations for Z = 4-Me2N in water, but increasingly strong negative deviations as the Me2SO content of the solvent increases.A similar trend is observed for Z = 4-MeO although the magnitude of the deviations, positive and negative, is much smaller.The 4-Me2N- and 4-MeO-derivatives also show positive deviations from a Broensted-type plot of log k1OH vs log Keq in water, while a similar plot in 90percent Me2SO-10percent water may or may not show small negative deviations.The negative deviations from the Hammett plot are caused by the strong resonance stabilization of the ?-donor-substituted β-nitrostyrenes which also depresses the equilibrium constants for these substrates.The positive deviations from the Hammett and Broensted-type plots are attributed to a preorganization of the electronic structure towards that of the product, induced by the through resonance that occurs with ?-donor substituents.This preorganization facilitates the delocalization of the negative charge into the nitro group at the transition state and enhances the intrinsic rate constant (K0 = k when K = 1) of the reaction.
- Bernasconi, Claude F.,Zitomer, Janie L.,Schuck, David F.
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- New insights into the catalytic reduction of aliphatic nitro compounds with hypophosphites under ultrasonic irradiation
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This work describes an efficient process for the reduction of nitro compounds to the corresponding amines with a catalytic amount of Pd/C (0.6 mol%), and a mixture of sodium hypophosphite and hypophosphorous acid as a reducing agent in H2O/2-MeTHF at 60 °C. The reaction was optimized under silent conditions. The conditions for the in situ production of H2 using the mixture NaH2PO2/H3PO2 were studied. The influence of ultrasonic activation was investigated both in terms of efficiency and kinetics. The reaction was shown to be efficient in water, at 70 °C with a quantitative conversion and a maximal yield in only 15 min thanks to the ultrasonic activation. Finally, ultrasound was proved to act as a physical agent of phase transfer.
- Letort,Lejeune,Kardos,Métay,Popowycz,Lemaire,Draye
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- Structural tuning enables piezochromic and photochemical properties in N-aryl-β-enaminones
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An efficient synthesis of N-aryl-β-enaminones via Et3N-mediated, one-pot three-component reaction of 4-hydroxycoumarin/dimedone, β-nitrostyrene/2-(2-nitrovinyl)thiophene, and arylamine in toluene under refluxed conditions is herein presented. Some prepared compounds were found to exhibit piezochromic properties. The XRD and SEM measurements of the piezochromic compound showed substantial crystal packing and morphology changes before and after grinding. Further, one prepared compound was found to be light-sensitive and can be converted to a furo[3,2-b]pyridin-2(4H)-one derivative upon UV irradiation. A plausible mechanism for this photochemical reaction was proposed.
- Hsieh, Wan-Chi,Manjappa, Kiran B.,Yang, Ding-Yah
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- Four-Step Domino Reaction Enables Fully Controlled Non-Statistical Synthesis of Hexaarylbenzene with Six Different Aryl Groups**
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Hexaarylbenzene (HAB) derivatives are versatile aromatic systems playing a significant role as chromophores, liquid crystalline materials, molecular receptors, molecular-scale devices, organic light-emitting diodes and candidates for organic electronics. Statistical synthesis of simple symmetrical HABs is known via cyclotrimerization or Diels–Alder reactions. By contrast, the synthesis of more complex, asymmetrical systems, and without involvement of statistical steps, remains an unsolved problem. Here we present a generally applicable synthetic strategy to access asymmetrical HAB via an atom-economical and high-yielding metal-free four-step domino reaction using nitrostyrenes and α,α-dicyanoolefins as easily available starting materials. Resulting domino product—functionalized triarylbenzene (TAB)—can be used as a key starting compound to furnish asymmetrically substituted hexaarylbenzenes in high overall yield and without involvement of statistical steps. This straightforward domino process represents a distinct approach to create diverse and still unexplored HAB scaffolds, containing six different aromatic rings around central benzene core.
- Dill, Maximilian,Grau, Benedikt W.,Hampel, Frank,Jux, Norbert,Kahnt, Axel,Tsogoeva, Svetlana B.
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- Surface modification of polyhedral nanocrystalline MgO with imidazolium carboxylates for dehydration reactions: A new approach
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The surface modification of nanomaterials with organic molecules and the utilization of modified materials in various applications is equally important. Here we demonstrate, the surface modification of polyhedral nano MgO with imidazolium carboxylate, which generates the NHC stabilized material MgO-[NHC]. The resultant material was successfully utilized in the catalytic dehydration of glucose under heterogeneous conditions. Furthermore, it was used in the dehydration of nitro alcohol to olefins in high yields. In addition, the surface modified catalyst was characterized by using various techniques like XRD, FE-SEM, TEM, FT-IR, XPS and AES analysis.
- Shaikh, Melad,Sahu, Mahendra,Khilari, Santimoy,Kumar, Atyam Kiran,Maji, Pathik,Ranganath, Kalluri V. S.
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- A diversity-oriented synthesis of polyheterocycles: Via the cyclocondensation of azomethine imine
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Pd-Catalyzed sequential reactions to afford skeletally diverse molecules are described. The reaction involved azomethine imine formation and a cyclocondensation reaction as individual steps. The methodology provides excellent regio- and stereocontrol. Skeletal diversity was ensured by changing the electrophilic counterpart of azomethine imine. Due to its broader diversity and complexity, the DOS methodology is likely to benefit drug discovery and development in the future.
- Ansari, Arshad J.,Pathare, Ramdas S.,Kumawat, Anita,Maurya, Antim K.,Verma, Sarika,Agnihotri, Vijai K.,Joshi, Rahul,Metre, Ramesh K.,Sharon, Ashoke,Pardasani,Sawant, Devesh M.
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- Design, synthesis and molecular docking study of novel pyrrole-based α-amylase and α-glucosidase inhibitors
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Abstract: In an effort to design and synthesize a new class of α-glucosidase and α-amylase inhibitors, we have synthesized novel pyrrole based molecules using molecular hybridization approach. These novel analogs were synthesized by the novel methodology developed in our lab which comprises of the multi-component direct synthesis route using hypervalent iodine reagent. The compounds were characterized by infrared, 1H nuclear magnetic resonance (NMR), 13C NMR and Mass Spectroscopy. These compounds were screened for their α-amylase and α- glucosidase activity. They showed a varying degree of inhibition with IC50 values ranging between 0.4 to 4.14 μmol/mL and 0.8 to 4.14 μmol/mL for α-amylase and α-glucosidase respectively. Compounds 3, 7, 12, and 18 showed excellent activity as compared to standard acarbose. This has identified a new class of α-amylase and α-glucosidase inhibitor which can be further developed as antihyperglycemic agents. The molecular docking analysis was carried out to better understand of interaction between α-amylase and α-glucosidase target and inhibitors in this series. We also generated a homology model for human α-glucosidase enzyme and identified the key residues at the binding site. The outcome of the study could be used for the rational design of potent and selective α-amylase and α-glucosidase inhibitors, respectively. Graphical abstract: [InlineMediaObject not available: see fulltext.].
- Jadhav, Nikhil C.,Pahelkar, Akshata R.,Desai, Neha V.,Telvekar, Vikas N.
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- Identification of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane-dithiocarbamate-nitrostyrene hybrid as potent antiproliferative and apoptotic inducing agent against cervical cancer cell lines
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The present study seeks to describe the design and synthesis of six new Michael adducts of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane-dithiocarbamate with nitrostyrenes and their in vitro antiproliferative activity against human cervical cancer cell lines [HeLa (HPV 18 positive), CaSki (HPV 16 positive) and ViBo (HPV negative) cervical cancer cell lines]. Virtual screening of the physicochemical properties of all compounds have also been presented. All the compounds exploited significant antiproliferative activity on the three cervical cancer cell lines. Compound 8a was found to be most potent, displaying in vitro antiproliferative activity against HeLa, CaSki and ViBo cervical cancer cell lines superior to Cisplatin and Paclitaxel with IC50 values 0.99 ± 0.007, 2.36 ± 0.016 and 0.73 ± 0.002 μM respectively. In addition, compound 8a did not trigger the necrosis cell death to the test cancer cell lines. Further mechanistic study revealed that compound 8a could inhibit the cancer cell proliferation by inducing apoptosis through caspase-3 activation. Moreover, cell cycle analysis indicated that compound 8a could arrest the cell cycle at the G1 phase for HeLa and CaSki cancer cells. At the predetermined IC50 values on cancer cells, compound 8a did not induce any necrotic (cytotoxic) death to the normal human lymphocytes. In the present design, (1S,4S)-2,5-diazabicyclo[2.2.1]heptane system was found to be superior than the piperazine counterpart 11.
- Laskar, Sujay,Sánchez-Sánchez, Luis,Flores, Sebastián M.,López-Mu?oz, Hugo,Escobar-Sánchez, María L.,López-Ortiz, Manuel,Hernández-Rodríguez, Marcos,Regla, Ignacio
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- (3S,4S)-N-substituted-3,4-dihydroxypyrrolidines as ligands for the enantioselective Henry reaction
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The enantioselective Henry reaction is a very important and useful carbon–carbon bond forming reaction. The execution of this reaction requires the use of efficient chiral catalysts. In this work, in situ formed complexes of N-substituted dihydroxypyrrolidines, chiral ligands derived from L-tartaric acid and amines, were evaluated as catalysts in the enantioselective Henry reaction. The results showed that the nature of the N-substituent on the ligand significantly influences the outcome of the reaction. Best results were obtained using a Cu (II) complex of (3S,4S)-N-benzyl-3,4-dihydroxypyrrolidine, in the presence of DIPEA, for the reaction of aromatic aldehydes with nitromethane, at room temperature, originating products with er up to 92:8 (R:S) and conversions up to 96%. The interaction between the pyrrolidine ligand and the copper ion, in isopropanol, was followed by UV-vis spectrophotometry, showing a 1:1 stoichiometry and a binding constant of 4.4. The results obtained will contribute to the design and development of more efficient chiral catalysts for this type of reaction.
- Rénio, Márcia R.R.,Sousa, Francisco J.P.M.,Tavares, Nélia C.T.,Valente, Artur J.M.,da Silva Serra, M. Elisa,Murtinho, Dina
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- Active Base Hybrid Organosilica Materials based on Pyrrolidine Builder Units for Fine Chemicals Production
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The catalytic activity of “pyrrolidine type” fragments included or anchored in the mesoporous silica supports or polymeric frameworks have been fully reported for enantioselective transformation. Nevertheless, low attention was focused on their catalytic abilities to perform base-catalyzed reaction. Accordingly, hybrid materials including pyrrolidine fragments in the mesoporous silica supports were prepared following different synthesis methods, such as micellar and fluoride sol-gel routes in absence of structural directing agents. Their great catalytic performance was explored for various base-catalyzed reactions to the formation of C?C bond through Knoevenagel, Claisen-Schmidt and Henry condensations under microwave irradiation. The benefits of microwave irradiation combined with suitable catalytic properties of pyrrolidine hybrid materials with strong base sites and high accessibility to active centers, allowed carrying out successfully base-catalyzed condensation reactions for the production of fine chemicals. Moreover, the hybrid catalyst exhibited high selectivity and good stability over different catalytic cycles contributing to environmental sustainability.
- Llopis, Sebastián,Velty, Alexandra,Díaz, Urbano
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p. 5012 - 5024
(2021/10/19)
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- A green metal-free "one-pot" microwave assisted synthesis of 1,4-dihydrochromene triazoles
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The synthesis of several 4-aryl-1,4-dihydrochromene-triazoles was achieved via a metal-free "one-pot"procedure using PEG400 as the sole solvent in an eco-friendly process. Using microwave irradiation, the triazole derivatives were obtained in good yields and short reaction times starting from readily accessible building blocks.
- Alves, Tania M. F.,Jardim, Guilherme A. M.,Ferreira, Marco A. B.
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p. 10336 - 10339
(2021/03/26)
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- Organocatalytic Asymmetric Synthesis of Aza-Spirooxindoles via Michael/Friedel-Crafts Cascade Reaction of 1,3-Nitroenynes and 3-Pyrrolyloxindoles
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An asymmetric [3+3] cyclization of nitroenynes and 3-pyrrolyloxindoles has been realized with a chiral bifunctional squaramide catalyst. This Michael/Friedel-Crafts cascade strategy provides a facile and efficient access to enantioenriched polycyclic aza-spirooxindoles with 32-95% isolated yields and excellent stereocontrol under mild reaction conditions.
- Ni, Qijian,Wang, Xuyang,Zeng, Da,Wu, Qianling,Song, Xiaoxiao
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supporting information
p. 2273 - 2278
(2021/04/05)
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- Skeletally Tunable Seven-Membered-Ring Fused Pyrroles
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We describe a copper-mediated method that enables the synthesis of seven-membered-ring fused pyrroles (7-mrFPs). The protocol proceeds via an in situ spiro-intermediate ring expansion and tolerates a library of 7-mrFP derivatives with a broad range of functional groups in a simple step with tangible parameters and substrate adaptations. These rare 7-mrFPs are now accessible on a millimolar scale, and selected examples exhibit high antioxidant activity.
- Andreou, Dimitrios,Essien, Nsikak B.,Pubill-Ulldemolins, Cristina,Terzidis, Michael A.,Papadopoulos, Athanasios N.,Kostakis, George E.,Lykakis, Ioannis N.
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supporting information
p. 6685 - 6690
(2021/09/11)
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- A nitrogen fixation strategy to synthesize NO: Via the thermally assisted photocatalytic conversion of air
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Developing a novel strategy for energy-efficient and clean synthesis of NO from distributed sources is highly desirable. Herein, we present a facile and green method to synthesize NO through the thermal-Assisted photocatalytic oxidation of N2 using simulated air as the reactant in a flow reactor. The TiO2/WO3 heterostructured nanorods were constructed and exhibited good activity for NO photosynthesis assisted by heating in the range of 200-350 °C. The yield rate of NO reached 0.16 mmol g-1 h-1 at 300 °C with a quantum efficiency of 0.31% at 365 nm. 15N isotope labeling experiments proved the origin of NO from N2 oxidation. Experimental and theoretical results revealed that the lattice oxygen in the heterostructures participated in the photooxidation reaction of N2, and the electron transfer from WO3 to TiO2 at the interface of the heterojunction under illumination could facilitate the adsorption of N2 and the formation of NO? intermediates and thus enhanced the photocatalytic N2 oxidation performance. Importantly, the solar-driven oxidation generated NO can be directly used for the synthesis of fine chemicals including nitric acid and β-nitrostyrolene. Our work opens a new avenue for nitrogen fixation via solar-driven N2 oxidation from distributed sources of air. This journal is
- Huang, Yanmei,Liu, Cuibo,Lu, Siyu,Wang, Changhong,Yu, Yifu,Yu, Yu,Zhang, Bin
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p. 19623 - 19630
(2020/10/13)
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- Physically mixed catalytic system of amino and sulfo-functional porous organic polymers as efficiently synergistic co-catalysts for one-pot cascade reactions
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In this article, acid/base bi-functional polymeric materials were prepared using physically mixed porous poly(divinylbenzene-co-4-vinylbenzenesulfonic acid) (P(DVB-VBS)) with sulfonic acid groups and poly(divinylbenzene-co-4-vinylbenzyl amine) (P(DVB-VBA)) with amino groups, which were synthesized by solvothermal polymerization of crosslinker DVB with either phenyl 4-vinylbenzenesulfonate (PVBS) or 4-vinylbenzyl amine hydrochloride (VBAH) functional monomers together with subsequent hydrolyzation or alkaline treatment. The bi-functional polymeric materials were utilized as a synergistic catalytic system for one-pot cascade reactions including deacetalization-Henry condensation reaction, deacetalization-Knoevenagel condensation reaction and the transformation of 3,4-dihydropyran derivatives to α-ester cyclohexenone compounds. The crosslinked polymeric frameworks effectively isolated sulfonic acid and primary amine groups to ensure their roles as both acid and base catalyst simultaneously in a one-pot system. The hierarchical porosity of a physically mixed acid/base co-catalyst system provided the possibility for the multi-step transformation of more complex substrates.
- Bian, Guomin,Huang, Xianpei,Liu, Fuyao,Qi, Yonglin,Sun, Zunming,Yang, Xinlin,Yang, Xinyue,Zhang, Mengmeng,Zhang, Wangqing
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p. 9546 - 9556
(2020/06/17)
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- Application of Fluorine- And Nitrogen-Walk Approaches: Defining the Structural and Functional Diversity of 2-Phenylindole Class of Cannabinoid 1 Receptor Positive Allosteric Modulators
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Cannabinoid 1 receptor (CB1R) allosteric ligands hold a far-reaching therapeutic promise. We report the application of fluoro- and nitrogen-walk approaches to enhance the drug-like properties of GAT211, a prototype CB1R allosteric agonist-positive allosteric modulator (ago-PAM). Several analogs exhibited improved functional potency (cAMP, β-arrestin 2), metabolic stability, and aqueous solubility. Two key analogs, GAT591 (6r) and GAT593 (6s), exhibited augmented allosteric-agonist and PAM activities in neuronal cultures, improved metabolic stability, and enhanced orthosteric agonist binding (CP55,940). Both analogs also exhibited good analgesic potency in the CFA inflammatory-pain model with longer duration of action over GAT211 while being devoid of adverse cannabimimetic effects. Another analog, GAT592 (9j), exhibited moderate ago-PAM potency and improved aqueous solubility with therapeutic reduction of intraocular pressure in murine glaucoma models. The SAR findings and the enhanced allosteric activity in this class of allosteric modulators were accounted for in our recently developed computational model for CB1R allosteric activation and positive allosteric modulation.
- Garai, Sumanta,Kulkarni, Pushkar M.,Schaffer, Peter C.,Leo, Luciana M.,Brandt, Asher L.,Zagzoog, Ayat,Black, Tallan,Lin, Xiaoyan,Hurst, Dow P.,Janero, David R.,Abood, Mary E.,Zimmowitch, Anaelle,Straiker, Alex,Pertwee, Roger G.,Kelly, Melanie,Szczesniak, Anna-Maria,Denovan-Wright, Eileen M.,Mackie, Ken,Hohmann, Andrea G.,Reggio, Patricia H.,Laprairie, Robert B.,Thakur, Ganesh A.
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p. 542 - 568
(2020/02/04)
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- One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes
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β-Nitrostyrenes underwent a Diels-Alder reaction with Danishefsky's diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated-5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated-4-nitrophenols. The reaction of nitrostyrenes with Danishefsky's diene could be conducted in one pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group, e.g., a thienyl group could be introduced into the nitrophenol framework.
- Asahara, Haruyasu,Hiraishi, Minami,Nishiwaki, Nagatoshi
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p. 1830 - 1836
(2020/09/15)
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- Novel approach in the synthesis of imidazo [1, 2-a] pyridine from phenyl acrylic acids
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This paper describes highly efficient concise method for the synthesis of imidazo[1,2-a] pyridine. It is a first report employing, amino pyridines, copper nitrate, and phenyl acrylic acids in the synthesis of imidazo[1,2-a] pyridine. The silent features of the devised protocol include the high yield, milder reaction conditions, and shorter reaction time.
- Mutkule, Nilesh,Bugad, Nageshprasad,Mokale, Santosh,Choudhari, Vilas,Ubale, Milind
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supporting information
p. 3186 - 3192
(2020/06/23)
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- Synthesis of functionalized carbon microspheres and their catalyst activity in C—O and C—N bond formation reactions
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Disclosed herein is a simple process for functionalization/grafting of carbon microspheres obtained from bagasse with various active functional groups onto it and use of the same as catalyst for various organic reactions, having very high selectivity and conversion rate.
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Page/Page column 8-9
(2019/02/14)
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- Substrate promiscuity of ortho-naphthoquinone catalyst: Catalytic aerobic amine oxidation protocols to deaminative cross-coupling and n-nitrosation
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ortho-Naphthoquinone-based organocatalysts have been identified as versatile aerobic oxidation catalysts. Primary amines were readily cross-coupled with primary nitroalkanes via deaminative pathway to give nitroalkene derivatives in good to excellent yields. Secondary and tertiary amines were inert to ortho-naphthoquinone catalysts; however, secondary nitroalkanes were readily converted by ortho-naphthoquinone catalysts to the corresponding nitrite species that in situ oxidized the amines to the corresponding N-nitroso compounds. Without using harsh oxidants in a stoichiometric amount, the present catalytic aerobic oxidation protocol utilizes the substrate promiscuity feature to provide a facile access to amine oxidation products under mild reaction conditions.
- Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
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p. 9216 - 9221
(2019/10/08)
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- NHC-Catalyzed Dual Stetter Reaction: A Mild Cascade Annulation for the Syntheses of Naphthoquinones, Isoflavanones, and Sugar-Based Chiral Analogues
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The N-heterocycle carbene (NHC)-catalyzed dual Stetter cascade reaction is discovered through coupling of β-nitrostyrene with phthalaldehyde under mild conditions to furnish valuable aryl-naphthoquinones. The generality of the new reaction is validated through the development of a C-C and O-C bond forming Stetter cascade reaction using salicylaldehydes to obtain functionalized dihydroisoflavanones. The mild NHC organocatalysis is successfully employed for the construction of optically pure sugar-based naphthoquinones and dihydroisoflavanones. Herein, NHC is found as a unique and powerful organocatalyst to construct homoatomic C-C cross-coupling, heteroatomic O-C bond formation, and cascade cyclization utilizing NO2 as a leaving group at ambient temperature. A mechanistic pathway of the new metal-free catalysis is predicted on the basis of our ESI-MS study of the ongoing reaction and literature.
- Mitra, Rajendra N.,Show, Krishanu,Barman, Debabrata,Sarkar, Satinath,Maiti, Dilip K.
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- Comprehensive evaluation of antioxidant effects of Japanese Kampo medicines led to identification of Tsudosan formulation as a potent antioxidant agent
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Oxidative stress due to the overproduction of reactive oxygen species plays an important role in the pathogenesis of various diseases. In the present study, we comprehensively evaluated the antioxidant activities of 147 oral formulations of Japanese traditional herbal medicines (Kampo medicines), representing the entire panel of oral Kampo medicines listed in the Japanese National Health Insurance Drug List, using in vitro radical scavenging assays, including the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity assay, the superoxide anion scavenging activity assay, and the oxygen radical absorption capacity assay. Three of the formulations tested, namely, Tsudosan, Daisaikoto, and Masiningan, showed the most potent in vitro antioxidant activities and were selected for further investigation of their intracellular and in vivo antioxidant effects. The results of the 2′,7′-dichlorodihydrofluorescin diacetate assay demonstrated that all three Kampo medicines significantly inhibited hydrogen peroxide-induced oxidative stress in human hepatocellular liver carcinoma HepG2 cells. In addition, Tsudosan significantly increased the serum biological antioxidant potential values when orally administrated to mice, indicating that it also had in vivo antioxidant activity. The potent antioxidant activity of Tsudosan may be one of the mechanisms closely correlated to its clinical usage against blood stasis.
- Sato, Naoko,Li, Wei,Takemoto, Hiroaki,Takeuchi, Mio,Nakamura, Ai,Tokura, Emi,Akahane, Chie,Ueno, Kanako,Komatsu, Kana,Kuriyama, Noriko,Onoda, Toshihisa,Higai, Koji,Koike, Kazuo
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p. 163 - 172
(2018/11/06)
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- Design, synthesis and evaluation of thiourea derivatives as antimicrobial and antiviral agents
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Background: The development of drug-resistant by bacteria appears rapidly and thus making the effectiveness of antibiotics severely limited. Methods: A series of thiourea derivatives was synthesized, characterized and evaluated for their in vitro antibacterial, antifungal and antiviral activities. Results: Structures of the newly synthesized compounds were confirmed by elemental and spectral analysis. The biological results showed that some of the target compounds displayed comparable antimicrobial and antiviral activities with reference drugs. Structure-activity relationship studies revealed that the ortho-chloro or fluoro substituted phenyl at Ar1 and substituted pyridinyl at Ar2 positions of the thiourea nucleus are essential for their in vitro antimicrobial and anti-HIV activity. In particular, compounds 8 and 10 showed better activity against the tested bacteria, fungi and viral strains than other synthesized PET derivatives reported in the present study. Conclusion: These results provide an encouraging lead that could be used for the development of new potent antiviral and antimicrobial agents.
- Ravichandran, Veerasamy,Shalini, Sivadasan,Kumar, Krishnan Suresh,Rajak, Harish,Agrawal, Ram Kishore
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p. 618 - 624
(2019/06/25)
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- Cinnamic acid derivative and preparation method and application thereof
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The invention provides a cinnamic acid derivative. The cinnamic acid derivative is of the structure as shown in the formula I. The invention also provides two methods for preparing the cinnamic acid derivative. The two methods depend on a single bond or double bonds in the structure shown in the formula I. The invention further provides a pesticide. The pesticide comprises the cinnamic acid derivative. In addition, the invention provides a sterilization method. The sterilization method includes the step of applying the cinnamic acid derivative or the pesticide to crops. The crops include rice,wheat, fruit trees and vegetables. The low-toxicity, low-residue-content and high-activity environment-friendly cinnamic acid derivative is developed, and the cinnamic acid derivative pesticide can replace traditional high-toxicity and high-residue-content pesticides.
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Paragraph 0210; 0211; 0212
(2019/10/22)
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- Base-catalyzed reactions enhanced by solid acids: Amine-catalyzed nitroaldol (Henry) reactions enhanced by silica gel or mesoporous silica SBA-15
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The reactions of various aldehydes with CH3NO2 catalyzed by Et3N, n-C6H13NH2, and Me2N(CH2)2NH2 were accelerated by the addition of silica gel to give aromatic (aliphatic) β-nitroalcohols, aromatic nitroalkenes, and aromatic 1,3-dinitroalkanes, respectively. Mesoporous silica SBA-15 showed higher activity than silica gel for the synthesis of aromatic nitroalkenes by the reactions of the corresponding aldehydes with CH3NO2 catalyzed by n-C6H13NH2.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
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supporting information
p. 392 - 396
(2017/12/28)
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- Double-shelled hollow mesoporous silica nanospheres as an acid-base bifunctional catalyst for cascade reactions
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Double-shelled hollow mesoporous silica nanospheres (HMS-Al@MS-NH2) have been successfully obtained using the shell-by-shell strategy, by which the isolated acidic (-Al) and basic (-NH2) sites were spatially incorporated in different shells. The characterization results indicate that HMS-Al@MS-NH2 possesses a hollow void and mesopores in both shells, and this favors the mass transfer of the reactants and products. As a spatially isolated acid-base bifunctional catalyst, HMS-Al@MS-NH2 proved to exhibit high catalytic performances in the one-pot deacetalization-Knoevenagel cascade reaction. Under the optimized conditions, the conversion of benzaldehyde dimethyl acetal approached ca. 100% for 2 h at 110 °C, mainly attributed to the isolated acidic and basic sites and to the hollow architecture and mesopores in the shells. Notably, the catalyst could be reused up to 4 times without obvious loss of activity and selectivity, indicating the high stability of the active acidic and basic sites in the framework. Moreover, the double-shelled hollow mesoporous silica spheres are also active and selective for the other cascade sequence of the deacetalization-Henry reaction.
- You, Chunzi,Yu, Chunqi,Yang, Xiaohui,Li, Yudong,Huo, Hang,Wang, Zhe,Jiang, Yanqiu,Xu, Xianzhu,Lin, Kaifeng
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p. 4095 - 4101
(2018/03/21)
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- Copper-Promoted Regioselective Synthesis of Polysubstituted Pyrroles from Aldehydes, Amines, and Nitroalkenes via 1,2-Phenyl/Alkyl Migration
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The facile copper-catalyzed synthesis of polysubstituted pyrroles from aldehydes, amines, and β-nitroalkenes is reported. Remarkably, the use of α-methyl-substituted aldehydes provides efficient access to a series of tetra- and pentasubstituted pyrroles via an overwhelming 1,2-phenyl/alkyl migration. The present methodology is also accessible to non α-substituted aldehydes, yielding the corresponding trisubstituted pyrroles. On the contrary, the use of ketones, in place of aldehydes, does not promote the organic transformation, signifying the necessity of α-substituted aldehydes. The reaction proceeds under mild catalytic conditions with low catalyst loading (0.3-1 mol %), a broad scope, very good functional-group tolerance, and high yields and can be easily scaled up to more than 3 mmol of product, thus highlighting a useful synthetic application of the present catalytic protocol. Based on formal kinetic studies, a possible radical pathway is proposed that involves the formation of an allylic nitrogen radical intermediate, which in turn reacts with the nitroalkene to yield the desired pyrrole framework via a radical 1,2-phenyl or alkyl migration.
- Andreou, Dimitrios,Kallitsakis, Michael G.,Loukopoulos, Edward,Gabriel, Catherine,Kostakis, George E.,Lykakis, Ioannis N.
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p. 2104 - 2113
(2018/02/23)
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- Synthesis of Benzo[4,5]imidazo[2,1-b]thiazole by Copper(II)-Catalyzed Thioamination of Nitroalkene with 1H-Benzo[d]imidazole-2-thiol
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A Copper(II)-catalyzed thioamination of β-nitroalkene with 1H-benzo[d]imidazole-2-thiol has been developed for the synthesis of benzo[4,5]imidazo[2,1-b]thiazole derivatives. A variety of N-fused benzoimidazothiazole derivatives are obtained in high yields through successive C?N and C?S bond formations. This protocol is also applicable to β-substituted β-nitroalkenes to afford 2,3-disubstituted benzoimidazothiazoles. (Figure presented.).
- Jana, Sourav,Chakraborty, Amrita,Shirinian, Valerii Z.,Hajra, Alakananda
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supporting information
p. 2402 - 2408
(2018/05/08)
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- A Continuous-Flow, Two-Step, Metal-Free Process for the Synthesis of Differently Substituted Chiral 1,2-Diamino Derivatives
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The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was successfully performed under continuous-flow conditions. After a preliminary screening with a 10-μL microreactor, to establish the best reaction conditions, the reduction was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity, that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished, either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based on the use of the very inexpensive and readily available reducing agent trichlorosilane. The final aim is to develop a two-step, continuous-flow process for the stereoselective, metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.
- Pirola, Margherita,Compostella, Maria Elena,Raimondi, Laura,Puglisi, Alessandra,Benaglia, Maurizio
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supporting information
p. 1430 - 1438
(2018/02/09)
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- Cooperative Multifunctional Catalysts for Nitrone Synthesis: Platinum Nanoclusters in Amine-Functionalized Metal–Organic Frameworks
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Nitrones are key intermediates in organic synthesis and the pharmaceutical industry. The heterogeneous synthesis of nitrones with multifunctional catalysts is extremely attractive but rarely explored. Herein, we report ultrasmall platinum nanoclusters (PtNCs) encapsulated in amine-functionalized Zr metal–organic framework (MOF), UiO-66-NH2 (Pt@UiO-66-NH2) as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By virtue of the cooperative interplay among the selective hydrogenation activity provided by the ultrasmall PtNCs and Lewis acidity/basicity/nanoconfinement endowed by UiO-66-NH2, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity, in comparison to Pt/carbon, Pt@UiO-66, and Pd@UiO-66-NH2. Pt@UiO-66-NH2 also outperforms Pt nanoparticles supported on the external surface of the same MOF (Pt/UiO-66-NH2). To our knowledge, this work demonstrates the first examples of one-pot synthesis of nitrones using recyclable multifunctional heterogeneous catalysts.
- Li, Xinle,Zhang, Biying,Tang, Linlin,Goh, Tian Wei,Qi, Shuyan,Volkov, Alexander,Pei, Yuchen,Qi, Zhiyuan,Tsung, Chia-Kuang,Stanley, Levi,Huang, Wenyu
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supporting information
p. 16371 - 16375
(2017/11/28)
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- New multicomponent reaction for the direct synthesis of β-aryl-γ-nitroesters promoted by hydrotalcite-derived mixed oxides as heterogeneous catalyst
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A new approach based on multicomponent/domino combined reactions for the synthesis of γ-nitroesters promoted by a mixed aluminium-magnesium oxides derived from hydrotalcite-like material was developed. Different γ-nitroesters were synthesized in 15-95percent yield using Meldrum's acid, aromatic aldehydes, nitromethane and different alcohols as reagents and solvents. The γ-aminobutyric acid derivatives, Phenibut and Baclofen, were prepared in 63 and 61percent overall yield, respectively, through a two steps synthetic strategy. A mechanistic pathway was proposed based on the gas chromatography mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS) experiments.
- D'Oca, Caroline R. M.,Naciuk, Fabricio F.,Silva, Jéssica C.,Guedes, Esthéfani P.,Moro, Celso C.,D'Oca, Marcelo G. M.,Santos, Leonardo S.,Natchigall, Fabiane M.,Russowsky, Dennis
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p. 285 - 298
(2016/12/18)
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- Compound and its preparation method and application
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The invention provides a compound and a preparation method therefore and application thereof. The compound is a compound shown in a formula I or an enantiomer, a diastereoisomer, raceme, pharmaceutically acceptable salt, a crystalline hydrate or a solvate of the compound, wherein R1 is optionally substituted phenyl, R2 is p-methylphenyl and X is C or N. The compound can be used for treating cancer related diseases. The formula I is shown in the description.
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Paragraph 0060; 0063
(2017/10/06)
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- 2-methyl-4-phenyl-1-pyrroline preparation method
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The invention discloses a 2-methyl-4-phenyl-1-pyrroline preparation method which includes the steps: S1, preparing phenyl nitro ethylene from benzaldehyde and nitromethane under catalysis of alkali metal hydroxide; S2, performing addition reaction on the phenyl nitro ethylene and acetone under catalysis of L-proline; S3, performing reduction and ring-closure on an addition product to obtain a target product. According to the preparation method, synthetic raw materials are easily obtained and low in price, and operation conditions are mild. Routes are simple and convenient in synthesis, silica-gel column chromatography is omitted after each step of reaction, and the preparation method is suitable for scientific research of laboratory mini-preparation and industrial production and amplification. Technical improvement of related drugs can be promoted, and various rich routes are provided for synthesis of the drugs.
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Paragraph 0027; 0028
(2017/09/05)
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- Benzo-hexatomic ring derivative used as DPP-4 inhibitor and application of benzo-hexatomic ring derivative
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The invention relates to a benzo-hexatomic ring derivative used as a DPP-4 inhibitor and application of the benzo-hexatomic ring derivative, in particular to compounds shown as in formula I, medicine compositions with the compounds shown as in the formula I and application of the compounds in preparing medicines for treating diseases related to DPP-4 or inhibiting the DPP-4.
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Paragraph 0502; 0503; 0504; 0505
(2016/10/09)
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- An Asymmetric Vinylogous Michael Cascade of Silyl Glyoximide, Vinyl Grignard, and Nitroalkenes via Long Range Stereoinduction
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A diastereoselective auxiliary-mediated vinylation/[1,2]-Brook rearrangement/vinylogous Michael cascade of silyl glyoximide, vinylmagnesium bromide, and nitroalkenes is described. The reaction occurs with complete regio- and diastereocontrol in good yield. The diastereoselectivity is induced by a rare instance of 1,7-chirality transfer that is hypothesized to arise from a trans-multihetero-decalin transition state. (Chemical Equation).
- Boyce, Gregory R.,Johnson, Jeffrey S.
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p. 1712 - 1717
(2016/03/01)
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- Palladium(II)-catalyzed C-C and C-O bond formation for the synthesis of C1-benzoyl isoquinolines from isoquinoline: N -oxides and nitroalkenes
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C1-Benzoyl isoquinolines can be generated via a palladium(ii)-catalyzed C-C and C-O coupling of isoquinoline N-oxides with aromatic nitroalkenes. The reaction proceeds through remote C-H bond activation and subsequent intramolecular oxygen atom transfer (OAT). In this reaction, the N-O bond was designed as a directing group in the C-H bond activation as well as the source of an oxygen atom.
- Li, Jiu-Ling,Li, Wei-Ze,Wang, Ying-Chun,Ren, Qiu,Wang, Heng-Shan,Pan, Ying-Ming
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supporting information
p. 10028 - 10031
(2016/08/15)
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- A 4-amino-3-phenyl-butyric acid hydrochloride method for the synthesis of
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A provided synthetic method for 4-amino-3-phenylbutyric acid hydrochloride comprises the steps: preparing ethyl benzoylacetate, preparing nitroethenylbenzene, preparing an addition product, and processing to obtain the product. The synthetic method is an integral technology for synthesizing 4-amino-3-phenylbutyric acid hydrochloride. The method is simple in technology, high in yield and relatively low in cost, and mainly solves the problems that an initial raw material used in the prior art is high in price, operation steps are tedious and a production process is large in pollution.
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Paragraph 0029
(2017/02/24)
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