- Waste-to-useful: A biowaste-derived heterogeneous catalyst for a green and sustainable Henry reaction
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Owing to the depletion of resources coupled with increasing waste generation, the conversion of waste biomass to value-added materials has gained interest. Here, we report for the first time the application of Musa acuminata (banana) peel ash (MAPA) as a heterogeneous catalyst for C-C bond formation via a Henry reaction under solvent-free conditions at ambient temperature. The catalyst was well characterized using different analytical techniques like FT-IR, SEM, TEM-EDS, XRD, XRF, XPS, BET and TGA, along with basicity determination by a Hammett indicator test and titration method. An excellent yield of nitroalcohol was obtained within 15-30 minutes. No dehydrated product was observed. The catalyst used in these studies has the advantage of being a waste material and is hence low-cost, easily prepared, recyclable and environmentally friendly. In addition, the use of a biogenic renewable catalyst, its atom economy, and room temperature and solvent-free reaction conditions and the avoidance of column chromatography make the protocol highly significant from green and sustainable chemistry perspectives.
- Rajkumari, Kalyani,Das, Diparjun,Pathak, Gunindra,Rokhum, Lalthazuala
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p. 2134 - 2140
(2019/02/05)
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- Production of (S)-β-Nitro Alcohols by Enantioselective C?C Bond Cleavage with an R-Selective Hydroxynitrile Lyase
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Hydroxynitrile lyase (HNL)-catalysed stereoselective synthesis of β-nitro alcohols from aldehydes and nitroalkanes is considered an efficient biocatalytic approach. However, only one S-selective HNL—Hevea brasiliensis (HbHNL)—exists that is appropriate for the synthesis of (S)-β-nitro alcohols from the corresponding aldehydes. Further, synthesis catalysed by HbHNL is limited by low specific activity and moderate yields. We have prepared a number of (S)-β-nitro alcohols, by kinetic resolution with the aid of an R-selective HNL from Arabidopsis thaliana (AtHNL). Optimization of the reaction conditions for AtHNL-catalysed stereoselective C?C bond cleavage of racemic 2-nitro-1-phenylethanol (NPE) produced (S)-NPE (together with benzaldehyde and nitromethane, largely from the R enantiomer) in up to 99 % ee and with 47 % conversion. This is the fastest HNL-catalysed route known so far for the synthesis of a series of (S)-β-nitro alcohols. This approach widens the application of AtHNL for the synthesis not only of (R)- but also of (S)-β-nitro alcohols from the appropriate substrates. Without the need for the discovery of a new enzyme, but rather by use of a retro-Henry approach, it was used to generate a number of (S)-β-nitro alcohols by taking advantage of the substrate selectivity of AtHNL.
- Rao, D. H. Sreenivasa,Padhi, Santosh Kumar
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p. 371 - 378
(2019/01/08)
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- Synthetic Diversity from a Versatile and Radical Nitrating Reagent
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We leverage the slow liberation of nitrogen dioxide from a newly discovered, inexpensive succinimide-derived reagent to allow for the C?H diversification of alkenes and alkynes. Beyond furnishing a library of aryl β-nitroalkenes, this reagent provides unparalleled access to β-nitrohydrins and β-nitroethers. Detailed mechanistic studies strongly suggest that a mesolytic N?N bond fragmentation liberates a nitryl radical. Using in situ photo-sensitized, electron paramagnetic resonance spectroscopy, we observed direct evidence of a nitryl radical in solution by nitrone spin-trapping. To further exhibit versatility of N-nitrosuccinimide under photoredox conditions, the late-stage diversification of an extensive number of C?H partners to prepare isoxazolines and isoxazoles is presented. This approach allows for the formation of an in situ nitrile oxide from a ketone partner, the presence of which is detected by the formation of the corresponding furoxan when conducted in the absence of a dipolarophile. This 1,3-dipolar cycloaddition with nitrile oxides and alkenes or alkynes proceeds in a single-operational step using a mild, regioselective, and general protocol with broad chemoselectivity.
- Zhang, Kun,Jelier, Benson,Passera, Alessandro,Jeschke, Gunnar,Katayev, Dmitry
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supporting information
p. 12929 - 12939
(2019/09/17)
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- An ionic liquid gel: A heterogeneous catalyst for Erlenmeyer-Plochl and Henry reactions
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An ionic liquid gel has been prepared by entrapping 1-butyl-3-methylimidazolium hydroxide ([Bmim]OH) in an aqueous agar gel. The ionic liquid gel has been characterized by Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and energy dispersive X-ray analysis (EDX). The ionic liquid gel has been successfully employed as a heterogeneous catalyst in the Erlenmeyer-Plochl reaction involving aldehydes, hippuric acid and acetic anhydride as well as in the Henry reaction between aldehydes and nitromethane in ethanol at room temperature. The heterogeneity of the ionic liquid gel has been confirmed by conducting hot filtration tests and leaching studies. Additionally, the ionic liquid gel could be easily recovered by simple filtration and reused five times without significant loss in catalytic activity.
- Jagadale, Megha,Naikwade, Altafhusen,Salunkhe, Rajashri,Rajmane, Mohan,Rashinkar, Gajanan
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p. 10993 - 11005
(2018/07/06)
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- Henry reaction catalyzed by copper(I) complexes of a new pyridine-containing macrocyclic ligand
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The synthesis and characterization of copper(I) complexes of the novel pyridine-containing macrocyclic ligand (PC-L) and their use as catalysts in the Henry reaction are reported. The pyridine-based 12-membered tetraaza macrocyclic (PC-L) ligand 1 can be
- Castano, Brunilde,Pedrazzini, Tommaso,Sisti, Massimo,Gallo, Emma,Ragaini, Fabio,Casati, Nicola,Caselli, Alessandro
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experimental part
p. 824 - 829
(2012/02/16)
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- Straightforward synthesis of nitroolefins by microwave- or ultrasound-assisted Henry reaction
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β-Nitroalcohol or nitroethylene derivatives can be obtained from aryl aldehydes and nitromethane under Henry condensation conditions. We present a new modification using microwave irradiation or ultrasound as the energy source. Microwave irradiation allowed a novel one-pot synthesis of nitroolefins from aryl aldehydes using ammonium acetate as a catalyst without solvent. Different reaction conditions, such as base, solvent, and reaction time were studied. Only small amounts of β-hydroxyl nitro compounds were isolated, using microwave irradiation for less than 25 min. In contrast, the use of ultrasound increased the yield of the nitroalcohols.
- Rodríguez, Jose M.,Dolors Pujol
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experimental part
p. 2629 - 2632
(2011/06/10)
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- Cyclen-catalyzed Henry reaction under neutral conditions
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A convenient cyclen-catalyzed Henry reaction of aldehydes with nitroalkanes under mild and neutral conditions is reported. This procedure constitutes the first cyclen-catalyzed synthesis of nitroalcohols and is adapted to the condensation of both aromatic and aliphatic aldehydes with nitromethane in THF at room temperature without addition of stoichiometric amount of the base. A wide range of substrates, β-nitroalcohols, were obtained in moderate to good yields (up to 98%) using this methodology.
- Vovard-Le Bray, Chloé,Jiang, Fan,Wu, Xiao-Feng,Sortais, Jean-Baptiste,Darcel, Christophe
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supporting information; experimental part
p. 4555 - 4557
(2010/10/02)
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- 1-Butyl-3-methyl-imidazolium tetrafluoroborate as a recyclable reaction medium for henry reaction
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A simple protocol for the Henry reaction has been developed in room temperature ionic liquid [bmim]BF4 using Na2CO3 as base. The 2-nitroalcohols have been obtained in good yields, and the ionic liquid was recycled.
- Khan, Faiz Ahmed,Sudheer,Sahu, Nilam
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p. 201 - 207
(2007/10/03)
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- Hydrotalcite catalysis in ionic liquid medium: A recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation
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Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF 6 and [bmim]BF4 without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.
- Khan, Faiz Ahmed,Dash, Jyotirmayee,Satapathy, Rashmirekha,Upadhyay, Sarasij K.
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p. 3055 - 3058
(2007/10/03)
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- A New and Efficient Synthesis of Pyrrolo[2,3-d]pyrimidine Anticancer Agents: Alimta (LY231514, MTA), Homo-Alimta, TNP-351, and Some Aryl 5-Substituted Pyrrolo[2,3-d]pyrimidines
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Alimta, as well as homo-Alimta, a nonbridged analogue of Alimta, and TNP-351 have been prepared by a new method that involves Michael addition of the appropriate 1-nitroalkene with 2,6-diamino-3H-pyrimidin-4-one or 2,4,6-triaminopyrimidine, followed by a Nef reaction of the resulting primary nitro Michael adduct. Spontaneous intramolecular cyclization of the resulting aldehyde with the pyrimidine 6-amino group yields the corresponding pyrrolo[2,3-d]pyrimidine. A series of previously unknown 5-arylpyrrolo[2,3-d]pyrimidines was prepared by the same methodology from the above pyrimidines and nitrostyrenes. It has been found that the intermediate primary nitro Michael adduct can be prepared in a single step by sonication of a mixture of an arylaldehyde, nitromethane, and the 6-aminopyrimidine in acetic acid containing ammonium acetate.
- Taylor, Edward C.,Liu, Bin
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p. 9938 - 9947
(2007/10/03)
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- New antimitotic agents with activity in multi-drug-resistant cell lines and in vivo efficacy in murine tumor models
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During a screen for compounds that could inhibit cell proliferation, a series of new tubulin-binding compounds was identified with the discovery of oxadiazoline 1 (A-105972). This compound showed good cytotoxic activity against non-multi-drug-resistant and multi-drug-resistant cancer cell lines, but its utility in vivo was limited by a short half-life. Medicinal chemistry efforts led to the discovery of indolyloxazoline 22g (A-259745), which maintained all of the in vitro activity seen with oxadiazoline 1, but also demonstrated a better pharmacokinetic profile, and dose-dependent in vivo activity. Over a 28 day study, indolyloxazoline 22g increased the life span of tumor-implanted mice by up to a factor of 3 upon oral dosing. This compound, and others of its structural class, may prove to be useful in the development of new chemotherapeutic agents to treat human cancers.
- Szczepankiewicz,Chiou,Credo,Alder,Nukkala,Zielinski,Jarvis,Mollison,Frost,Bauch,Hui,Liu,Claiborne,Li,Rosenberg,Jae,Tasker,Gunawardana,Von Geldern,Gwaltney II,Wu-Wong,Gehrke
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p. 4416 - 4430
(2007/10/03)
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- Synthesis of a 2,5-diaryloxazoline as a potential platelet-activating factor antagonist
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2,5-Bis-(3,4,5-trimethoxyphenyl)-2-oxazoline (5, MDL 100,270) was designed as a potential platelet-activating factor (PAF) antagonist on the basis of computer modeling comparison studies with known PAF antagonists. An efficient, four-step synthesis of oxa
- Peet,Burkhart,Broersma,Heminger
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p. 419 - 423
(2007/10/02)
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