102-96-5Relevant articles and documents
Humic substances as catalysts m condensation reactions
Klavins, Maris,Dipane, Judite,Babre, Kristine
, p. 737 - 742 (2001)
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.
Water-controlled nitro-oximation of alkenes under catalyst-free conditions
Tang, Lin,Yang, Zhen,Chang, Xueping,Zou, Guodong,Zhou, Yuqiang,Rao, Weihao,Ma, Xiantao,Zhao, Geng
, p. 4272 - 4275 (2018)
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.
Cu(II) homogeneous and heterogeneous catalysts for the asymmetric Henry reaction
Jones, Matthew D.,Cooper, Christine J.,Mahon, Mary F.,Raithby, Paul. R.,Apperley, David,Wolowska, Joanna,Collison, David
, p. 8 - 14 (2010)
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.
A simple O-sulfated thiohydroximate molecule to be the first micromolar range myrosinase inhibitor
Cerniauskaite, Deimante,Gallienne, Estelle,Karciauskaite, Henreta,Farinha, Andrea S.F.,Rousseau, Jolanta,Armand, Sylvie,Tatibou?t, Arnaud,Sackus, Algirdas,Rollin, Patrick
, p. 3302 - 3305 (2009)
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.
Mild and Regioselective Three-component Heteroarylation-Nitration of Alkenes with Imidazo[1,2-a]pyridines and tert-Butyl Nitrite
Liu, Ping,Sun, Peipei,Xie, Shentong,Zhang, Jie
, (2020)
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.).
Facile and efficient michael addition of indole to nitroolefins catalyzed by zn(OAc)22H2O
Ji, Xiang,Tong, Haibo,Yuan, Yu
, p. 372 - 379 (2011)
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.
Zeolite Y-assisted nitration of aromatic and heterocyclic compounds and decarboxylative nitration of α,β-unsaturated acids under non-conventional conditions
Sudhakar Chary,Rajanna,Krishnaiah,Srinivas
, p. 1430 - 1434 (2016)
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.
Metal ion exchange in Prussian blue analogues: Cu(ii)-exchanged Zn-Co PBAs as highly selective catalysts for A3 coupling
Marquez, Carlos,Cirujano, Francisco G.,Smolders, Simon,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk,De Baerdemaeker, Trees
, p. 3946 - 3954 (2019)
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.
A novel tandem sequence to pyrrole syntheses by 5-endo-dig cyclization of 1,3-enynes with amines
Bharathiraja, Ganesan,Sakthivel, Sekarpandi,Sengoden, Mani,Punniyamurthy, Tharmalingam
, p. 4996 - 4999 (2013)
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.
Kinetic and Mechanistic Examination of Acid-Base Bifunctional Aminosilica Catalysts in Aldol and Nitroaldol Condensations
Collier, Virginia E.,Ellebracht, Nathan C.,Lindy, George I.,Moschetta, Eric G.,Jones, Christopher W.
, p. 460 - 468 (2016)
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.
Yolk-shell-structured mesoporous silica: A bifunctional catalyst for nitroaldol-Michael one-pot cascade reaction
An, Juzeng,Cheng, Tanyu,Xiong, Xi,Wu, Liang,Han, Bin,Liu, Guohua
, p. 5714 - 5720 (2016)
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.
Continuous-flow synthesis using a column reactor packed with heterogeneous catalysts: A convenient production of nitroolefins by using amino-functionalized silicagel
Ishitani, Haruro,Furiya, Yuichi,Kobayashi, Shū
, p. 6229 - 6232 (2017)
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.
Charge-transfer interactions: An efficient tool for recycling bis(oxazoline)-copper complexes in asymmetric henry reactions
Didier, Dorian,Magnier-Bouvier, Caroline,Schulz, Emmanuelle
, p. 1087 - 1095 (2011)
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
Synthesis and catalytic properties of hybrid mesoporous materials assembled from polyhedral and bridged silsesquioxane monomers
Diaz, Urbano,Garcia, Teresa,Velty, Alexandra,Corma, Avelino
, p. 8659 - 8672 (2012)
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
Squaramide-Linked Chloramphenicol Base Hybrid Catalysts for the Asymmetric Michael Addition of 2,3-Dihydrobenzofuran-2-carboxylates to Nitroolefins
Yan, Linjie,Huang, Guanxin,Wang, Haifeng,Xiong, Fangjun,Peng, Haihui,Chen, Fener
, p. 99 - 103 (2018)
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).
Ethylenediamine-functionalized magnetic Fe3O4@SiO2 nanoparticles: cooperative trifunctional catalysis for selective synthesis of nitroalkenes
Xue, Fengjun,Dong, Yahao,Hu, Peibo,Deng, Yanan,Wei, Yuping
, p. 73684 - 73691 (2015)
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.
New insights into the catalytic reduction of aliphatic nitro compounds with hypophosphites under ultrasonic irradiation
Letort,Lejeune,Kardos,Métay,Popowycz,Lemaire,Draye
, p. 4583 - 4590 (2017)
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.
Structural tuning enables piezochromic and photochemical properties in N-aryl-β-enaminones
Hsieh, Wan-Chi,Manjappa, Kiran B.,Yang, Ding-Yah
, p. 34088 - 34094 (2019)
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.
Surface modification of polyhedral nanocrystalline MgO with imidazolium carboxylates for dehydration reactions: A new approach
Shaikh, Melad,Sahu, Mahendra,Khilari, Santimoy,Kumar, Atyam Kiran,Maji, Pathik,Ranganath, Kalluri V. S.
, p. 82591 - 82595 (2016)
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.
Sousa et al.
, p. 3320,3323 (1969)
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
Laskar, Sujay,Sánchez-Sánchez, Luis,Flores, Sebastián M.,López-Mu?oz, Hugo,Escobar-Sánchez, María L.,López-Ortiz, Manuel,Hernández-Rodríguez, Marcos,Regla, Ignacio
, p. 621 - 635 (2018)
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.
A green metal-free "one-pot" microwave assisted synthesis of 1,4-dihydrochromene triazoles
Alves, Tania M. F.,Jardim, Guilherme A. M.,Ferreira, Marco A. B.
, p. 10336 - 10339 (2021/03/26)
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.
Skeletally Tunable Seven-Membered-Ring Fused Pyrroles
Andreou, Dimitrios,Essien, Nsikak B.,Pubill-Ulldemolins, Cristina,Terzidis, Michael A.,Papadopoulos, Athanasios N.,Kostakis, George E.,Lykakis, Ioannis N.
supporting information, p. 6685 - 6690 (2021/09/11)
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.
