- Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
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An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20?000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18?600 and 19?200 h-1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10?000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated.
- Chen, Yang,Liu, Changmeng,Xu, Dong,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 6050 - 6058
(2021/08/23)
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- Nitroalkene reduction in deep eutectic solvents promoted by BH3NH3
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Deep eutectic solvents (DESs) have gained attention as green and safe as well as economically and environmentally sustainable alternative to the traditional organic solvents. Here, we report the combination of an atom-economic, very convenient and inexpensive reagent, such as BH3NH3, with bio-based eutectic mixtures as biorenewable solvents in the synthesis of nitroalkanes, valuable precursors of amines. A variety of nitrostyrenes and alkyl-substituted nitroalkenes, including α- and β-substituted nitroolefins, were chemoselectively reduced to the nitroalkanes, with an atom economy-oriented, simple and convenient experimental procedure. A reliable and easily reproducible protocol to isolate the product without the use of any organic solvent was established, and the recyclability of the DES mixture was successfully investigated.
- Benaglia, Maurizio,Boselli, Monica Fiorenza,Faverio, Chiara,Gonzalez, Patricia Camarero,Puglisi, Alessandra
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supporting information
p. 1041 - 1047
(2021/05/17)
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- Reduction of α,β-unsaturated nitroolefins into nitroalkanes with Hantzsch ester promoted by isothiouronium salts
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α,β-Unsaturated nitroolefins were reduced into nitroalkanes with a Hantzsch ester, promoted by S-benzyl isothiouronium iodide. The reactions proceeded successfully to afford the desired products in high yields and with excellent chemoselectivity.
- Kang, Sungmin,Lee, Haney,Kim, Taek Hyeon
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p. 2460 - 2465
(2019/08/07)
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- Crystallization Does It All: An Alternative Strategy for Stereoselective Aza-Henry Reaction
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An efficient and experimentally straightforward method for the stereoselective synthesis of a variety of β-nitro-α-amino carboxylic acids via aza-Henry (nitro-Mannich) reaction of aldimines is disclosed, yielding either anti- or a rarely reported syn-configuration. The reaction operates directly on free glyoxylic acid and generates imine species in situ. Crystallization-controlled diastereoselectivity enables isolation of the target compounds in high enantio- and diastereomeric purities by a simple filtration.
- Mar?eková, Michaela,Ger?a, Peter,?oral, Michal,Moncol, Ján,Berke?, Du?an,Kolarovi?, Andrej,Jakubec, Pavol
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supporting information
p. 4580 - 4584
(2019/06/17)
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- Nano-NiFe2O4 as an efficient catalyst for regio- and chemoselective transfer hydrogenation of olefins/alkynes and dehydrogenation of alcohols under Pd-/Ru-free conditions
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Here, we have demonstrated the magnetic nano-NiFe2O4 catalyzed transfer hydrogenation of olefins/alkynes using isopropyl alcohol as a source of hydrogen under ligand/base/Pd-/Ru-metal-free conditions, and dehydrogenation of alcohols under oxidant-free conditions.
- Payra, Soumen,Saha, Arijit,Banerjee, Subhash
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p. 52495 - 52499
(2016/06/13)
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- Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes
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Iron(III) oxide is a low-cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe2O3 with high surface area-to-volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4-5 nm γ-Fe2O3 nanoparticles by a polymer-assisted aggregating self-assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open-pore structure with high surface area (up to 167 m2 g-1) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ-Fe2O3 to α-Fe2O3 and to Fe3O4 under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large-scale synthesis.
- Papadas, Ioannis T.,Fountoulaki, Stella,Lykakis, Ioannis N.,Armatas, Gerasimos S.
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p. 4600 - 4607
(2016/03/22)
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- Catalyst-free chemoselective reduction of the carbon-carbon double bond in conjugated alkenes with Hantzsch esters in water
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A simple, efficient and green protocol for chemoselective reduction of carbon-carbon double bond in conjugated alkenes with Hantzsch esters is described. Without any additional catalysts, a series of conjugated alkenes with strong electron-withdrawing groups were reduced in water with excellent yield. Functional groups such as nitrile, ester, nitro, fluoro, chloro, bromo, furanyl and benzyl are all tolerated by the reaction conditions employed. The Royal Society of Chemistry.
- He, Qi,Xu, Zhihong,Jiang, Dehong,Ai, Wensi,Shi, Ronghua,Qian, Shan,Wang, Zhouyu
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p. 8671 - 8674
(2014/03/21)
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- Unusual reactivity of nitronates with an aryl alkyl carbonate: Synthesis of α-amino esters
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The monoanions of nitroalkanes are ambident nucleophiles that react with carbonate electrophiles through the oxygen atom. Products arising from reactivity at the carbon atom will yield α-nitro esters, which are precursors for α-amino esters. We demonstrate this in the reactions of nitroalkanes with benzyl phenyl carbonate and DABCO where α-nitro esters are obtained instead of nitrile oxides. The products are readily reduced to α-amino esters. This pathway could be a safe alternative to the Strecker reaction.
- Reddy, Golipalli Ramana,Mukherjee, Debopreeti,Chittoory, Arjun Kumar,Rajaram, Sridhar
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supporting information
p. 5874 - 5877
(2015/01/08)
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- Useful extensions of the henry reaction: Expeditious routes to nitroalkanes and nitroalkenes in aqueous media
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The products of the Henry nitroaldol reaction from nitromethane and several aldehydes were reduced to the corresponding nitroalkanes with (n-Bu) 3SnH in water under microwave irradiation (80 °C/10 min), or dehydrated to the corresponding nitroalkenes with K2CO3 in water (generally 0-5 °C/20 min). Both "one-pot" reactions occur in excellent yields across a range of aliphatic and aromatic (including heteroaromatic) substrates. It seems likely that the deoxygenation of the nitroaldols occurs via coordination of an oxygen atom of the nitro group with a tin atom, which facilitates hydride delivery in the transition state. The elimination of water from the nitroaldols in mild base is likely driven by the stability of the conjugated nitroalkene products. The elimination required workup with 2 N HCl, which likely displaces a nitroalkane-nitroalkene equilibrium towards the latter. These extensions of the Henry reaction lead to products not easily obtained otherwise.
- Chandrasekhar, Sosale,Shrinidhi, Annadka
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p. 3008 - 3018
(2014/10/16)
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- S-benzyl isothiouronium chloride as a recoverable organocatalyst for the reduction of conjugated nitroalkenes with Hantzsch ester
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The reduction of conjugated nitroalkenes into nitroalkanes with Hantzsch ester using S-benzyl isothiouronium chloride as a recoverable organocatalyst was successfully accomplished with high yield and excellent chemoselectivity.
- Nguyen, Quynh Pham Bao,Kim, Jae Nyoung,Kim, Taek Hyeon
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supporting information; experimental part
p. 6513 - 6516
(2012/08/28)
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- The highly chemoselective transfer hydrogenation of the carbon-carbon double bond of conjugated nitroalkenes by a rhodium complex
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Chemoselective transfer hydrogenation of conjugated nitroalkenes catalyzed by [RhCl2Cp·]2-diamine complex (Cp ·=η5-C5Me5) using HCOOH/Et3N (5:2) (TEAF) as a hydrogen source was realized. A variety of nitrostyrenes, β-methyl nitrostyrenes, and 3-methyl-4-nitro-5-alkenyl- isoxazoles were reduced smoothly in good to excellent yields in short reaction time. Other functional groups are inert under the reaction conditions.
- Xiang, Jing,Sun, Er-Xiao,Lian, Chun-Xia,Yuan, Wei-Cheng,Zhu, Jin,Wang, Qiwei,Deng, Jingen
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experimental part
p. 4609 - 4620
(2012/07/28)
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- Catalyst-free and solventless Hantzsch ester mediated reduction of nitroolefins at elevated temperature
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A catalyst-free and solventless protocol for the reduction of nitroolefins to the corresponding nitroalkanes at 100°C has been developed. Various nitroalkenes have been reduced in good to excellent yield with short reaction times.
- Chauhan, Pankaj,Kaur, Kirandeep,Bala, Neeraj,Kumar, Vikas,Chimni, Swapandeep Singh
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experimental part
p. 304 - 309
(2011/05/02)
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- Organocatalytic biomimetic reduction of conjugated nitroalkenes
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A thiourea-catalyzed biomimetic reduction of conjugated nitroalkenes has been developed. Various aromatic and aliphatic conjugated nitroalkenes can be reduced to give the respective nitroalkanes with good yields under mild conditions. This protocol is not only practical, but may also provide insight into the mechanisms of redox transformations in biological systems. Georg Thieme Verlag Stuttgart.
- Zhang, Zhiguo,Schreiner, Peter R.
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p. 2559 - 2564
(2008/03/13)
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- The yeast-mediated reduction of nitrostyrenes in organic solvent systems
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A range of nitrostyrenes have been reduced with dried baker's yeast in an organic solvent system. It was found that the reduction proceeded smoothly to give the corresponding nitroalkanes in good yield and with higher efficiency than the corresponding aqueous reaction system. No evidence for reduction of the nitro group was observed. In the case of β-methyl nitrostyrenes, racemic mixtures were formed, and it was shown that this is not due to racemization of the product.
- Bak, Radoslaw R.,McAnda, Anita F.,Smallridge, Andrew J.,Trewhella, Maurie A.
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p. 1257 - 1260
(2007/10/03)
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- REDUCTION OF AROMATIC NITROALKENES WITH BAKER'S YEAST
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Aromatic nitroalkenes were reduced chemoselectively with baker's yeast to give the corresponding nitroalkanes.
- Takeshita, Mitsuhiro,Yoshida, Sachiko,Kohno, Yoichiro
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p. 553 - 562
(2007/10/02)
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- Tributyltin Hydride Addition to Nitroalkenes: A Convenient Procedure for the Conversion of Nitroalkenes into Nitroalkanes and Carbonyl Compounds
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A new procedure for the reduction of nitroalkenes by using n-tributyltin hydride as reducing agent is desribed.The reaction proceeds under almost neutral conditions and works well even in the presence of other reduceable functionalities.Hydrolysis and Nef reaction of the resulting nitronates furnished nitroalkanes and carbonyl compounds respectively in high yields.Application of this methodology to the preparation of β-lactam building blocks is also made.
- Palomo, Claudio,Aizpurua, Jesus M.,Cossio, Fernando P.,Garcia, Jesus M.,Lopez, M. Concepcion,Oiarbide, Mikel
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p. 2070 - 2078
(2007/10/02)
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- Selective Reduction of Carbon-Carbon Double Bonds with an NAD(P)H Model-Acetic Acid System
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The carbon-carbon double bond in conjugated nitro and certain carbonyl compounds was reduced smoothly and selectively by Hantzsch ester (HEH), an NAD(P)H model, in the presence of a small amount of acetic acid.
- Inoue, Yoshio,Imaizumi, Shin,Itoh, Hiromitsu,Shinya, Takao,Hashimoto, Harukichi,Miyano, Sotaro
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p. 3020 - 3022
(2007/10/02)
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- In Situ Generation and Synthetic Application of 2-Phenylbenzimidazoline to the Selective Reduction of Carbon-Carbon Double Bonds of Electron-Deficient Olefins
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2-Phenylbenzimidazoline (PBI) as a mild, selective, and convenient reducing agent was efficiently generated in situ from o-phenylenediamine and benzaldehyde in alcohols.A generally applicable method for the selective reduction of carbon-carbon double bonds of a variety of electron-deficient olefins with an alcoholic solution of PBI is described.The reduction of α,β-unsaturated ketones to the corresponding saturated ketones could also be accomplished (but, less effectively) with PBI with the aid of a Lewis-acid catalyst. 1-Methyl-2-(o-nitrophenyl)benzimidazoline prepared and isolated by the reaction of o-nitrobenzaldehyde with N-methyl-o-phenylenediamine reduced benzylidenemalononitrile to give benzylmalononitrile and 1-methyl-2-(o-nitrophenyl)benzimidazoline in high yields.This shows the validity of PBI to be the actual reducing species in the present reduction system.From a mechanistic study, the present reductions could be interpreted in terms of a mechanism involving a synchronous transport of a pair of hydrogens or a sequential transfer of a hydride and a proton from PBI to the olefins.
- Chikashita, Hidenori,Nishida, Shuichi,Miyazaki, Makoto,Morita, Yasuhiro,Itoh, Kazuyoshi
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p. 737 - 746
(2007/10/02)
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- AN IMPROVED, SIMPLE SYNTHESIS OF 3-METHYL-2-(4-METHYLPHENYL) CYCLOPENTEN-2-ONE: AN IMPORTANT INTERMEDIATE IN CUPARENE SYNTHESIS
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Conjugate addition of phenyl-1-methyl-4-(2-nitroethyl) to methyl vinyl ketone in presence of basic alumina, following by Nef reaction and basic cyclization, affords 3-methyl-2-(4-methyl phenyl) cyclopenten-2-one in good yield.
- Ballini, Roberto,Petrini, Marino,Marotta, Emanuela
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p. 543 - 548
(2007/10/02)
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- THE REACTIONS OF BENZYLIDENEMALONONITRILES AND β-NITROSTYRENES WITH O-PHENYLENEDIAMINE INCLUDING THE NEW ORGANIC REDOX REACTIONS BETWEEN THE OLEFINS AND 2-PHENYLBENZIMIDAZOLINES
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The reactions of benzylidenemalononitriles and β-nirtostyrenes with o-phenylenediamine in ethanol at boiling temperature gave the reduced products of the olefins.The reactions were rationalised on the basis of the role of 2-phenylbenzimidazolines as a hydrogen donor.
- Itoh, Kazuyoshi,Ishida, Hideaki,Chikashita, Hidenori
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p. 1117 - 1118
(2007/10/02)
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