- The first conversion of primary alkyl halides to nitroalkanes under aqueous medium
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Primary nitroalkanes and α,ω-dinitroalkanes can be easily obtained in aqueous medium by reaction of the corresponding halo derivatives with silver nitrite. The procedure works well with both alkyl bomide and alkyl iodide and proceeds in satisfactory to good yields even in the presence of other functionalities, minimizing the formation of the undesired alkyl nitrites.
- Ballini, Roberto,Barboni, Luciano,Giarlo, Guido
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- 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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- 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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- 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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- 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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- Visible-light-promoted C-C bond cleavage: Photocatalytic generation of iminium ions and amino radicals
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Photoscissors: Structurally variable and synthetically robust iminium ions and amino radicals species could be simultaneously generated by visible-light-promoted photoredox cleavage of the C-C bonds in simple vicinal diamine precursors under very mild reaction conditions. Copyright
- Cai, Shunyou,Zhao, Xinyang,Wang, Xinbo,Liu, Qisong,Li, Zigang,Wang, David Zhigang
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p. 8050 - 8053
(2012/08/29)
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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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- Cascade formation of isoxazoles: Facile base-mediated rearrangement of substituted oxetanes
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Give me five! Nitro compounds and oxetan-3-one react through an intriguing cascade sequence to give isoxazole-4-carbaldehydes using inexpensive reagents in a one-pot procedure (see scheme; Ms=methanesulfonyl). A variety of 3-substituted isoxazole-4-carbaldehydes were obtained in high overall yields.
- Burkhard, Johannes A.,Tchitchanov, Boris H.,Carreira, Erick M.
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p. 5379 - 5382
(2011/07/08)
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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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- Polymer-supported hantzsch 1,4-dihydropyridine ester: An efficient biomimetic hydrogen source for the reduction of ketimines and electron-withdrawing group conjugated olefins
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A polymer-supported Hantzsch 1,4-dihydropyridine ester was observed to be a useful selective reducing agent for the reduction of ketimines and electron-withdrawing conjugated olefins. The rate of the reduction of electron-withdrawing conjugated olefins is dependent on the nature of the conjugated substituents and could be enhanced by microwave irradiation. The reduction of (Z)-α-cyano-β-bromomethylcinnamates to cyclopropane derivatives using polymer-supported Hantzsch 1,4-dihydropyridine ester was found to proceed stereoselectively and in good yields.
- Che, Jun,Lam, Yulin
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experimental part
p. 1752 - 1758
(2010/09/11)
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- A recyclable organocascade reaction system: Stereoselective precipitation of optically active cis-δ-lactols with quaternary stereocenters during the Michael-hemiacetalization reaction
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A cascade Michael-hemiacetalization reaction between β-substituted β-nitroethanols and α,β-unsaturated aldehydes is described, which provides a convenient and efficient synthesis for cis-δ-lactols with quaternary stereocenters in moderate yields with excellent enantioselectivity. Based on the selective precipitation of cis-δ-lactols, which were isolated by filtration, the catalytic system in the filtrate can be reused directly and recycled for eight times without any obvious deterioration in enantioselectivity. Copyright
- Zhang, Fanglin,Wei, Mohui,Dong, Junfang,Zhou, Yirong,Lu, Dengfu,Gong, Yuefa,Yang, Xiangliang
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supporting information; experimental part
p. 2875 - 2880
(2011/01/05)
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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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- Metal-directed Synthesis of Aminobenzyl Polyaza Macrocycles: Candidates for Attachment to Polymers and Biomolecules
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Copper(II)-directed condensation between 4,7-diazadecane-1,10-diamine, formaldehyde and 1-nitro-3-(2-nitroethyl)benzene yielded the macrocyclic copper(II) ion.Reduction (Zn,HCl) gave the pendant-arm macrocycle 10-(3-aminobenzyl)-1,4,8,12-tetraazacyclopentadec-10-ylamine as the hydrochloride salt.Condensation reactions with 1-nitro-4-(2-nitroethyl)benzene and 2-phenylnitroethane were also successful.The capacity of the aminobenzyl C-pendant introduced by this facile chemistry for covalent attachment has been examined by attachment of 10-(3-aminobenzyl)-1,4,8,12-tetraazacyclopentadec-10-ylamine to the acidic cation-exchange resin CM Bio-Gel A and to horse heart cytochrome c, employing a water-soluble carbodiimide coupling agent at pH 5 to promote amide formation.The attachment was probed by copper(II) complexation to the bound macrocycle and subsequent spectroscopic or voltammetric analysis.
- Bayada, Anne,Lawrance, Geoffrey A.,Maeder, Marcel,O'Leary, Margaret A.
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p. 3107 - 3112
(2007/10/02)
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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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- 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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