122-57-6Relevant articles and documents
One-pot, three-component approach to the synthesis of 3,4,5-trisubstituted pyrazoles
Kamal, Ahmed,Sastry, K. N. Visweswara,Chandrasekhar,Mani, Geeta Sai,Adiyala, Praveen Reddy,Nanubolu, Jagadeesh Babu,Singarapu, Kiran Kumar,Maurya, Ram Awatar
, p. 4325 - 4335 (2015)
An operationally simple and high yielding protocol for the synthesis of polyfunctional pyrazoles has been developed through one-pot, three-component coupling of aldehydes, 1,3-dicarbonyls, and diazo compounds as well as tosyl hydrazones. The reaction proceeds through a tandem Knoevenagel condensation, 1,3-dipolar cycloaddition, and transition metal-free oxidative aromatization reaction sequence utilizing molecular oxygen as a green oxidant. The scope of the reaction was studied by varying the aldehyde, 1,3-dicarbonyl, and diazo component individually.
Encapsulating mesoporous metal nanoparticles: Towards a highly active and stable nanoreactor for oxidative coupling reactions in water
Zou, Houbing,Dai, Jinyu,Wang, Runwei
, p. 5898 - 5901 (2019)
We design and prepare a highly active and stable nanoreactor via encapsulating various mesoporous metal nanoparticles with an amphiphilic hollow shell, which presents excellent performance in oxidative coupling reactions in water for efficient production of α,β-unsaturated ketones.
A mechanistic investigation of Biginelli reaction under base catalysis
Kamal Raj,Rao, H. Surya Prakash,Manjunatha, Sulur G.,Sridharan,Nambiar, Sudhir,Keshwan, Jaikumar,Rappai, Jayan,Bhagat, Sagar,Shwetha,Hegde, Dinesh,Santhosh
, p. 3605 - 3609 (2011)
The mechanism of the three component base mediated Biginelli dihydropyrimidines synthesis was investigated using Accurate Mass TOF LC-MS-ESI and Tandem TOF LC-MS-ESI. We suggest hemiaminal as a possible intermediate leading to the formation of Biginelli product. Under our current experimental conditions we did not observe any bis-ureide as reported by ji et al.
Effects of dendritic interface on enantioselective catalysis by polymer-bound prolines
Kehat, Tzofit,Goren, Kerem,Portnoy, Moshe
, p. 394 - 401 (2012)
Dendritic effects have been observed in the past for a number of metal-based catalysts, but only rarely for organocatalysts, and particularly chiral organocatalysts. In the current study, l-proline was immobilized as an ester or amide on polyether dendritic spacers attached to polystyrene. The ester-including catalysts showed a remarkable positive dendritic effect on yield, but even more so on enantioselectivity, in the aldol reaction of acetone with aromatic aldehydes. The positive dendritic effect of the aforementioned catalytic systems on the yield, diastereo- and enantioselectivity of a three-component Mannich reaction was of an even greater magnitude. A series of experiments marked the possibility of catalysis by homogenous l-proline, detached from the resin during the reaction, highly unlikely. Model comparative studies with catalysts equipped with linear or only partially dendritic spacers emphasized the superiority of the fully dendritic spacer architecture.
Fe-catalyzed dithiane radical induced C?S bond activation?addition to α, β-unsaturated ketones
Min, Deng,Yuan, Xinyu,Liu, Teng,Liu, Jian,Tang, Shouchu
, p. 1795 - 1799 (2018)
An efficient and clean strategy to construct organosulfur compounds has been developed via a Fe-catalyzed dithiane C?S bond activation/addition process with α, β-unsaturated ketones. This C?S activation protocol exhibits excellent reactivities, and up to 92% yield of the corresponding thioether-thioester derivatives could be obtained under the mild conditions, allowing the ready preparation of a number of synthetically valuable S-linked conjugates. (Figure presented.).
Modular Pincer-type Pyridylidene Amide Ruthenium(II) Complexes for Efficient Transfer Hydrogenation Catalysis
Melle, Philipp,Manoharan, Yanisha,Albrecht, Martin
, p. 11761 - 11774 (2018)
A set of bench-stable ruthenium complexes with new N,N,N-tridentate coordinating pincer-type pyridyl-bis(pyridylideneamide) ligands was synthesized in excellent yields, with the pyridylidene amide in meta or in para position (m-PYA and p-PYA, respectively). While complex [Ru(p-PYA)(MeCN)3]2+ is catalytically silent in transfer hydrogenation, its meta isomer [Ru(m-PYA)(MeCN)3]2+ shows considerable activity with turnover frequencies at 50% conversion TOF50 = 100 h-1. Spectroscopic, electrochemical, and crystallographic analyses suggest considerably stronger donor properties of the zwitterionic m-PYA ligand compared to the partially π-acidic p-PYA analogue, imparted by valence isomerization. Further catalyst optimization was achieved by exchanging the ancillary MeCN ligands with imines (4-picoline), amines (ethylenediamine), and phosphines (PPh3, dppm, dppe). The most active catalyst was comprised of the m-PYA pincer ligand and PPh3, complex [Ru(m-PYA)(PPh3)(MeCN)2]2+, which reached a TOF50 of 430 h-1 under aerobic conditions and up to 4000 h-1 in the absence of oxygen. The presence of oxygen reversibly deactivates the catalytically active species, which compromises activity, but not longevity of the catalyst. Ligand exchange kinetic studies by NMR spectroscopy indicate that the strong trans effect of the phosphine is critical for high catalyst activity. Diaryl, aryl-alkyl, and dialkyl ketones were hydrogenated with high conversion, and α,β-unsaturated ketones produced selectively the saturated ketone as the only product due to exclusive C=C bond hydrogenation, a distinctly different selectivity from most other transfer hydrogenation catalysts.
Efficient C-C cross-coupling reactions by (isatin)-Schiff base functionalized magnetic nanoparticle-supported Cu(II) acetate as a magnetically recoverable catalyst
Miri, Seyedeh Simin,Khoobi, Mehdi,Ashouri, Fatemeh,Jafarpour, Farnaz,Rashidi Ranjbar, Parviz,Shafiee, Abbas
, p. 1232 - 1246 (2015)
Copper catalysts were simply fabricated through surface modification of superparamagnetic iron nanoparticles with indoline-2,3-dione(isatin)-Schiff-base and interaction with Cu from low-cost commercially available starting materials. Catalysts were characterized using atomic absorption spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, UV/Vis spectroscopy, scanning electron microscopy, and transmission electron microscopy. These catalysts showed high efficiency for phosphine-free Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions with good diversity and generality. The catalysts could be easily recovered and reused several times without a significant loss in their catalytic activity and stability.
Encapsulation of N,N',N''-tricyclohexylguanidine in hydrophobic zeolite Y: Synthesis and catalytic activity
Sercheli, Ricardo,Ferreira, Alfredo L. B.,Guerreiro, Mario C.,Vargas, Rogerio M.,Sheldon, Roger A.,Schuchardt, Ulf
, p. 1325 - 1328 (1997)
N,N',N''-Tricyclohexylguanidine was encapsulated in hydrophobic zeolite Y by reacting N,N'-dicyclohexylcarbodiimide with cyclohexylamine within the supercage. The encapsulated guanidine catalyzes the addition reaction of acetone to benzaldehyde forming 4-phenyl-4-hydroxybutan-2-one as the principal product, as opposed to the homogeneous system which produces 4-phenyl-3-buten-2-one via condensation reaction.
Synthesis of 1-hydrocarbon substituted cyclopropyl silyl ketones
Honda, Mitsunori,Sasaki, Sho,Nishimoto, Tsuyoshi,Koshiro, Hiromoto,Kunimoto, Ko-Ki,Segi, Masahito
, p. 3777 - 3781 (2018)
The synthesis of cyclopropyl silyl ketones possessing a hydrocarbon group at 1-position of three-membered ring was investigated. The reaction of sulfoxonium ylide with α,β-unsaturated acylsilanes derived from α,β-unsaturated aldehydes did not afford the desired acylsilane derivatives. Instead, the corresponding silyl enol ethers were yielded exclusively. On the other hand, the Corey-Chaykovsky cyclopropanation of α-substituted α,β-unsaturated aldehydes proceeded well to give 1-substituted cyclopropyl aldehydes. The silyl substitution of formyl proton in the obtained aldehydes via umpolung of carbonyl group afforded the target acylsilanes.
Chromium trioxide supported onto copper sulfate as an efficient oxidizing agent for oxidation of alcohols under solvent free conditions
Kiasat, Ali Reza,Kazemi, Foad,Nourbakhsh, Kazem
, p. 457 - 461 (2004)
Alcohols are rapidly oxidized to carbonyl compounds using CrO3 supported onto CuSO4 under solvent free conditions. Over-oxidation of aldehydes to carboxylic acids and damage to carbon-carbon double bond is not observed by this method.
Application of high pressure, induced by water freezing, to the direct asymmetric aldol reaction
Hayashi, Yujiro,Tsuboi, Wataru,Shoji, Mitsuru,Suzuki, Noriyuki
, p. 4353 - 4356 (2004)
High pressure, induced by water freezing, has been successfully applied to the direct catalytic asymmetric aldol reaction, in which higher yield and better enantioselectivity can be realized than in the reaction at room temperature under 0.1MPa.
Chiral 2,6-lutidinyl-biscarbene complexes of palladium
Tulloch,Danopoulos,Tizzard,Coles,Hursthouse,Hay-Motherwell,Motherwell
, p. 1270 - 1271 (2001)
Chiral complexes of palladium, 1, with the new tridentate "pincer" ligand 2,6-lutidinyl-biscarbene (C∧N∧C), have been prepared; in the solid state they exhibit helical C2 symmetrical structures which are persistent in solution at least up to 80°C; the chiral nature of 1 has been established by NMR methods using Pirkle's acid as a chiral discriminating agent; racemic mixtures of 1 are highly active catalysts in Heck coupling reactions.
Silica-immobilized piperazine: A sustainable organocatalyst for aldol and Knoevenagel reactions
Shanmuganathan, Saravanakumar,Greiner, Lasse,De María, Pablo Domínguez
, p. 6670 - 6672 (2010)
Silica-supported piperazine was found to be an efficient catalyst for aldol reactions of aromatic aldehydes and ketones with straightforward product isolation and catalyst reuse. Furthermore, the catalyst is active in Knoevenagel-type reactions to afford coumarin derivatives, using 2-methyltetrahydrofuran (2-MeTHF) as a novel bio-based solvent.
Carbenoid-mediated elimination of sulfides and selenides. A mild and efficient method for introducing α,β-double bonds to electron-withdrawing substituents
Gautier, Arnaud,Garipova, Goulnara,Deléens, Reynald,Piettre, Serge R.
, p. 4959 - 4962 (2002)
Cycloalkanes bearing both an electron-withdrawing group and an arylsulfenyl or arylselenenyl function in β-position are shown to react with 2 equiv. of a carbenoid species to generate the corresponding Michael acceptor. The reaction occurs under very mild conditions and affords the products in good to excellent yields. The process constitutes a useful alternative to the oxidation/syn-elimination sequence.
Palladium containing periodic mesoporous organosilica with imidazolium framework (Pd@PMO-IL): An efficient and recyclable catalyst for the aerobic oxidation of alcohols
Karimi, Babak,Elhamifar, Dawood,Clark, James H.,Hunt, Andrew J.
, p. 7420 - 7426 (2011)
The application of a novel palladium containing ionic liquid based periodic mesoporous organosilica (Pd@PMO-IL) catalyst in the aerobic oxidation of primary and secondary alcohols under molecular oxygen and air atmospheres is investigated. It was found that the catalyst is quite effective for the selective oxidation of several activated and non-activated alcoholic substrates. The catalyst system could be successfully recovered and reused several times without any significant decrease in activity and selectivity. Moreover, the hot filtration test, atomic absorption spectroscopy (AA) and kinetic study with and without selective catalyst poisons showed that the catalyst works in a heterogeneous pathway without any palladium leaching in reaction solution. Furthermore, nitrogen-sorption experiment and transmission electron microscopy (TEM) image proved the superior stability of high-ordered PMO-IL mesostructure during reaction process. TEM image also confirmed the presence of well-distributed Pd-nanoparticles in the uniform mesochannels of the material. These observations can be attributed to the ionic liquid nature of PMO-IL mesostructure which facilitates the reaction through production, chemical immobilization and stabilization of active palladium nanoparticles, as well as preventing Pd-agglomeration during overall process.
Asymmetric aldol reaction in a continuous-flow reactor catalyzed by a highly reusable heterogeneous peptide
Oetvoes, Sandor B.,Mandity, Istvan M.,Fueloep, Ferenc
, p. 179 - 185 (2012)
A solid-supported peptide-catalyzed continuous-flow (CF) process was developed for asymmetric aldol reactions. The catalyst was readily synthesized and immobilized by solid-phase peptide synthesis (SPPS) on a swellable polymer support in one single step. Ignoring the peptide cleavage from the resin means no work-up, no purification, and no product loss. After thorough optimization of the reaction conditions, synthetically useful β-hydroxyketone products were obtained in high yields and stereoselectivities. It was found that the heterogeneous catalytic reaction is diffusion-controlled under the present conditions; thus, elevation of the pressure is necessary to maximize conversion of the flow process. Besides being simple and efficient, the described method is also rapid and promisingly productive, with short residence times on the catalyst bed. The immobilized peptidic catalyst is highly recyclable, while further advantageous features are the ease of product isolation and the possibility of facile scale-up, furnishing sustainable catalytic methodology.
Zeolites with isolated-framework and oligomeric-extraframework hafnium species characterized with pair distribution function analysis
Iida, Takayuki,Ohara, Koji,Román-Leshkov, Yuriy,Wakihara, Toru
, p. 7914 - 7919 (2018)
Zeolites containing framework heteroatoms (e.g., Ti, Sn, and Hf) with open coordination sites behave as solid-state Lewis acids and exhibit remarkable catalytic properties unachievable with bulk oxides. However, direct evidence confirming the incorporation of such heteroatom species into the zeolite framework is difficult to obtain because of the limited number of analytical methods capable of discerning framework incorporation from extraframework species. In this work, the structural environments of hafnium (Hf) framework and extraframework species added post-synthetically into ?BEA zeolites were analyzed using coupled pair distribution function (PDF) and diffuse reflectance (DR) UV-vis measurements. PDF analysis enabled the visualization and identification of framework and extraframework HfOx species, both of which were undetectable by traditional X-ray and neutron diffraction methods. Reactivity data from the aldol condensation of benzaldehyde and acetone confirmed that framework Hf species are responsible for catalytic activity.
Acid-Base Pairs in Lewis Acidic Zeolites Promote Direct Aldol Reactions by Soft Enolization
Lewis, Jennifer D.,Van De Vyver, Stijn,Romn-Leshkov, Yuriy
, p. 9835 - 9838 (2015)
Hf-, Sn-, and Zr-Beta zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions.
Studies on ketene and its derivatives. XCII. Reaction of diketene with benzaldehyde, cinnamaldehyde, and β-phenylcinnamaldehyde
Kato,Chiba,Sato
, p. 3877 - 3879 (1978)
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Fe3O4?l-Proline/Pd nanocomposite for one-pot tandem catalytic synthesis of (±)-warfarin from benzyl alcohol: Synergistic action of organocatalyst and transition metal catalyst
Tomer, Sanjiv O.,Soni, Hemant P.
, p. 6517 - 6531 (2019)
One-pot synthesis of (±)-warfarin, an anticoagulant, has been achieved from benzyl alcohol in a 'green way' by using a multicomponent catalyst. For the purpose, l-proline capped Fe3O4 nanoparticles (Fe3O4?l-proline NPs) were synthesized and metallic palladium was loaded on its surface (Fe3O4?l-proline/Pd NCs). The morphology, particle size and shape were studied by using FESEM and TEM analysis. The Pd present on the surface was responsible for oxidation of benzyl alcohol and its derivatives to the corresponding aldehyde in situ. This in turn, condensed with acetone to form the aldol condensation product, benzylideneacetone, at 70 °C due to the presence of the l-proline organocatalyst on the surface of Fe3O4 NPs. Later, 4-hydroxycoumarin was introduced to condense with in situ generated benzylideneacetone by a Michael addition to form the target product (±)-warfarin. It was established that benzyl alcohol can be converted into the final product, (±)-warfarin, with an overall 35% yield within 5 days in a single-pot process. This process requires a rise in temperature in stages to a maximum of 100 °C and 1 atm pressure of dioxygen gas. An important aspect of the developed process is the avoidance of loss of costly Pd by leaching and catalyst recovery by the use of a magnetic field. The use of a solvent like PEG-400 makes the process green in a true sense. The interaction of l-proline with Fe3O4 NPs and the presence of Pd on the surface were confirmed by the FTIR and XRD patterns, respectively. The present study hereby suggests a combined 3-step mechanism for the production of the target product warfarin. Pilot-scale one-pot production of (±)-warfarin was carried out and a flow diagram with various unit processes is presented.
Ionic liquid catalysed synthesis of β-hydroxy ketones
Karmee, Sanjib Kumar,Hanefeld, Ulf
, p. 1118 - 1123 (2011)
Different acidic ionic liquids (ILs; namely, 1-methylimidazolium tetrafluoroborate, 1-methylimidazolium trifluoroacetate, N-methyl-2-pyrrolidone hydrogen sulfate, N,N,N-trioctyl-n-butanesulfonic acid ammonium hydrogen sulfate, 1-methyl-3-(3-sulfobutyl)imidazolium hydrogen sulfate) and basic ILs (namely, 1,1,3,3-tetramethylguanidinium lactate and choline hydroxide) were tested as catalysts for the aldol reaction. The choline hydroxide catalysed reaction gave high yield (94.3%) and selectivity of the 4-hydroxy-4-phenylbutan- 2-one after a short reaction time (15min) at 0°C. This article demonstrates the potential of choline hydroxide, which is a derivative of choline and a naturally occurring water-soluble essential nutrient, as a highly active and selective green catalyst.
Inhibition of Autophagy by a Small Molecule through Covalent Modification of the LC3 Protein
Chen, Kaixian,Chen, Zhifeng,Dang, Yongjun,Ding, Hong,Fan, Shijie,Hu, Junchi,Jiang, Hualiang,Li, Lianchun,Li, Quanfu,Lin, Tingting,Lu, Junyan,Luo, Cheng,Otomo, Chinatsu,Otomo, Takanori,Tan, Minjia,Tao, Hongru,Wan, Wei,Wen, Yi,Xie, Yuli,Xu, Pan,Yao, Zhiyi,Yue, Liyan,Zhang, Bidong,Zhang, Naixia,Zhang, Yuanyuan,Zhou, Bing,Zhu, Mingrui
supporting information, p. 26105 - 26114 (2021/11/09)
The autophagic ubiquitin-like protein LC3 functions through interactions with LC3-interaction regions (LIRs) of other autophagy proteins, including autophagy receptors, which stands out as a promising protein–protein interaction (PPI) target for the intervention of autophagy. Post-translational modifications like acetylation of Lys49 on the LIR-interacting surface could disrupt the interaction, offering an opportunity to design covalent small molecules interfering with the interface. Through screening covalent compounds, we discovered a small molecule modulator of LC3A/B that covalently modifies LC3A/B protein at Lys49. Activity-based protein profiling (ABPP) based evaluations reveal that a derivative molecule DC-LC3in-D5 exhibits a potent covalent reactivity and selectivity to LC3A/B in HeLa cells. DC-LC3in-D5 compromises LC3B lipidation in vitro and in HeLa cells, leading to deficiency in the formation of autophagic structures and autophagic substrate degradation. DC-LC3in-D5 could serve as a powerful tool for autophagy research as well as for therapeutic interventions.
Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
Fiorio, Jhonatan L.,Rossi, Liane M.
, p. 312 - 318 (2021/01/29)
The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
Oxidation of fluoroalkyl alcohols using sodium hypochlorite pentahydrate [1]
Kirihara, Masayuki,Suzuki, Katsuya,Nakakura, Kana,Saito, Katsuya,Nakamura, Riho,Tujimoto, Kazuki,Sakamoto, Yugo,Kikkawa, You,Shimazu, Hideo,Kimura, Yoshikazu
, (2021/02/05)
Fluoroalkyl alcohols are effectivity oxidized to the corresponding fluoroalkyl carbonyl compounds by reaction with sodium hypochlorite pentahydrate in acetonitrile in the presence of acid and nitroxyl radical catalysts. Although the reaction proceeded slower under a nitroxyl radical catalyst- free condition, the desired carbonyl compounds were obtained in high yields. For the reaction with fluoroalkyl allylic alcohols, the corresponding α,β-epoxyketone hydrates were obtained in high yields.
