- Formation and Out-of-Equilibrium, High/Low State Switching of a Nitroaldol Dynamer in Neutral Aqueous Media
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The nitroaldol reaction is demonstrated as an efficient dynamic covalent reaction in phosphate buffers at neutral pH. Rapid equilibration was recorded with pyridine-based aldehydes, and dynamic oligomerization could be achieved, leading to nitroaldol dynamers of up to 17 repeating units. The dynamers were applied in a coherent stimuli-responsive molecular system in which larger dynamers transiently existed out-of-equilibrium in a neutral aqueous system rich in formaldehyde, controlled by nitromethane.
- Elofsson, Ulla,Karalius, Antanas,Kravchenko, Oleksandr,Ramstr?m, Olof,Szabó, Zoltán,Yan, Mingdi,Zhang, Yang
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supporting information
p. 3434 - 3438
(2020/02/05)
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- A process for preparing taurine (by machine translation)
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The invention discloses a method for preparing taurine, especially relates to nitromethane as materials to prepare taurine. The method comprises the following steps: 1) the use of the neutralizing agent to adjust the pH value of the taurine ammonium, thus get the taurine and ammonium sulfite, and then separate out and leach taurine, to respectively obtain the taurine crude and contains a sulfurous acid ammonium filtrate; 2) will nitromethanes poly formaldehyde in the reaction under alkaline conditions, so as to obtain the nitro-ethanol; 3) step 1) obtained in the contains a sulfurous acid ammonium filtrate and step 2) obtained in the nitro-ethanol reaction, so as to obtain the nitro ethyl sulfonic acid ammonium; 4) the step 3) the obtained nitro ethyl ammonium using a reducing agent, so as to obtain taurine ammonium, after separation leaves the water level and catalyst, to obtain the taurine ammonium; 5) use of step 4) obtained in the taurine ammonium cycle step 1) to step 4). The method energy-saving, environmental protection, safety and reliability. (by machine translation)
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Paragraph 0033-0035
(2017/06/09)
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- Method for preparing taurine and co-producing bicarbonate
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The invention discloses a method for preparing taurine and co-producing bicarbonate. The method comprises the step of leading carbon dioxide gas or adding a carbon dioxide water solution to an amino ethyl sulfonate water solution of alkali metal or ammonium to regulate a pH value so as to obtain the taurine and the bicarbonate. The method can replace an existing taurine preparation method of using sulfuric acid or sulfur dioxide to regulate the pH value, meanwhile can treat boiler exhaust gas, turns the carbon dioxide in the exhaust gas into wealth, co-produces the bicarbonate and is a safe, environmentally-friendly and energy-saving method for producing the taurine and co-producing the bicarbonate.
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Paragraph 0039; 0040
(2016/10/08)
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- Organocatalytic enantioselective formal C(sp2)-H alkylation
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An organocatalytic enantioselective formal C(sp2)-H alkylation is reported. This alkylative desymmetrization of prochiral 2,2-disubstituted cyclopentene-1,3-dione is catalyzed by a bifunctional tertiary aminourea derivative, utilizes air-stable and inexpensive nitroalkanes as the alkylating agents, and delivers synthetically versatile five-membered carbocycles containing an all-carbon quaternary stereogenic center remote from the reaction site in excellent enantioselectivity.
- Manna, Madhu Sudan,Mukherjee, Santanu
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supporting information
p. 130 - 133
(2015/01/30)
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- Metal-free ring expansion of indoles with nitroalkenes: A simple, modular approach to 3-substituted 2-quinolones
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3-Substituted 2-quinolones are obtained via a novel metal-free transannulation reaction of 2-nitroolefins with 2-substituted indoles in polyphosphoric acid. This acid-mediated cascade transformation operates via the ANRORC (Addition of Nucleophile, Ring Opening, and Ring Closure) mechanism and can be used in combination with the Fisher indole synthesis to offer a practical three-component hetero-annulation approach to 2-quinolones from arylhydrazines, 2-nitroalkenes, and acetophenone. An alternative entry to this chemistry employing the alkylation of electron-rich arenes and hetarenes with 1-(2-indolyl)-2-nitroalkene has also been demonstrated.
- Aksenov, Alexander V.,Smirnov, Alexander N.,Aksenov, Nicolai A.,Aksenova, Inna V.,Matheny, Jonathon P.,Rubin, Michael
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p. 8647 - 8656
(2015/03/03)
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- Convenient procedure for the indium-mediated hydroxymethylation of active bromo compounds: Transformation of ketones into α-hydroxymethyl nitroalkanes
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A very simple, safe and powerful method for the hydroxymethylation of 2-bromoesters and lactones under anhydrous conditions that avoids the use of gaseous formaldehyde is described. Moreover, under these conditions, bromonitroalkanes were converted into the corresponding α- monohydroxymethylated nitroalkanes, which are precursors of the corresponding α-amino acids. Considering the easy transformation of ketones into bromonitroalkanes, this represents a method for the formal synthesis of α-amino acids from ketones. Georg Thieme Verlag Stuttgart New York.
- Soengas, Raquel G.,Estévez, Amalia M.
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supporting information; experimental part
p. 2625 - 2627
(2010/12/18)
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- tert-butyl ethers: Renaissance of an alcohol protecting group. Facile cleavage with cerium(III) chloride/sodium iodide
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The tert-butoxy derivative is one of the most underused alcohol protecting groups. After having developed an easy and useful protocol for its introduction, we offer here a simple procedure for its removal by treatment with anhydrous CeCl3 and NaI in CH3CN. The procedure led to the successful cleavage of aliphatic and aromatic tert-butyl ethers and was compatible with various other functionalities and protecting groups present in the molecule.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Locatelli, Manuela,Marcantoni, Enrico,Melchiorre, Paolo,Sambri, Letizia
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p. 905 - 910
(2007/10/03)
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- LaCl3·7H2O-promoted regioselective ring opening of epoxides using NaNO2 in ether-water system: A facile synthesis of 2-nitroalcohols
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A convenient and efficient synthesis of 2-nitroalcohols has been achieved by regioselective ring opening of epoxides using LaCl3·7H 2O and NaNO2 in ether-H2O system at room temperature. The reaction afforded the corresponding products in good to excellent yields under mild conditions.
- Borah, Jagat C.,Gogoi, Siddhartha,Boruwa, Joshodeep,Barua, Nabin C.
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p. 873 - 878
(2007/10/03)
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- Solvent free tetrahydropyranylation of phenols and alcohols over zeolites HSZ as reusable catalysts
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Phenols and alcohols are tetrahydropyranylated in the presence of zeolites HSZ in good to excellent yields and selectivities. Addition of methanol performs the complete deprotection.
- Ballini, Roberto,Bigi, Franca,Carloni, Silvia,Maggi, Raimondo,Sartori, Giovanni
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p. 4169 - 4172
(2007/10/03)
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- Kinetics of reversible carbon deprotonation of 2-nitroethanol and 2-nitro-1,3-propanediol by hydroxide ion, water, amines, and carboxylate ions. A normal br?nsted α despite an imbalanced transition state
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Rates of reversible carbon deprotonation of 2-nitroethanol (2) and 2-nitro-1,3-propanediol (3) by hydroxide ion, water, amines, and carboxylate ions and pKa values for the ionization at carbon (pKaCH) and oxygen (pKaOH) and ionization of the aci-forms (pKaNOH) were determined in aqueous solution at 25 °C. The pKaCH values for 2 and 3 are 8.60 and 7.68, respectively, as compared to 10.22 for CH3NO2. The acidifying effect of the CH2OH groups is attributed to a combination of inductive electron withdrawal and hyperconjugative stabilization of the respective nitronate ions, possibly coupled with intramolecular hydrogen bonding stabilization of this ion. The higher acidity of 2-nitroethanol compared to nitromethane is reflected in higher rates of proton transfer from 2-nitroethanol, implying a "normal" Br?nsted α between 0 and 1. This contrasts with the negative α value based on the reaction of OH- with nitromethane, nitroethane, and 2-nitropropane (Kresge, A. J. Can. J. Chem. 1974, 52, 1897). Reasons why a normal α value is observed in the current system are discussed.
- Bernasconi, Claude F.,Panda, Markandeswar,Stronach, Michael W.
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p. 9206 - 9212
(2007/10/03)
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- 2-(TRIMETHYLSILYL)ETHYL CHLOROFORMATE: A CONVENIENT REAGENT FOR PROTECTION OF HYDROXYL FUNCTION
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2-(Trimethylsilyl)ethyl chloroformate reacts with alcohols to give carbonates in high yield. n-Bu4NF in THF(0.2M) solution for 10 min or ZnBr2 or ZnCl2 in CH3NO2 for 10 min regenerate the alcohol at 20 deg C.
- Gioeli, Carlo,Balgobin, Neil,Josephson, Staffan,Chattopahyaya, Jyoti B.
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p. 969 - 972
(2007/10/02)
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- Process for preparing biotin
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Biotin is prepared by (a) ozonizing methylcyclohexene; (b) reacting nitromethane with the methyl-6-oxohexanoate from a to form 7-nitro-6 hydroxyheptanoic acid methyl ester; (c) acylating to form the corresponding 6 acyloxy compound; (d) forming a double bond at the 6 position; (e) reacting the product of d with nitroethanethiol to form dl-7-thia-6-nitromethyl-9-nitro-nonanoic acid methyl ester; (f) forming a furoxan by cyclization; (g) reducing the furoxan and acylating to form dl-2(4-carbomethoxybutyl)-3,4-bis(acylamido)-2,5-dihydro thiophene; (h) selectively hydrogenating to form the 3,4-cis-bis(acylamido)-2,5-dihydro thiophene; and (i) hydrolyzing and cyclizing to form dl-biotin. The products formed at steps (e)-(h) are novel, as are the individual steps (e), (f), (g), and (h).
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- Process for preparing β-nitroethanethiol
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β-Nitroethanethiol is prepared by reacting a carboxylic acid ester of β-nitroethananol with trisodium thiophosphate and hydrolyzing the reasulting thiophosphate ester to form β-nitroethanethiol.
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