- 1,3-Difunctionalization of β-alkyl nitroalkenes via combination of Lewis base catalysis and radical oxidation
-
Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.
- Wang, Ye,Zheng, Lei,Shi, Xiaodong,Chen, Yunfeng
-
p. 886 - 889
(2021/02/01)
-
- Metal-Free Deoxygenation of Chiral Nitroalkanes: An Easy Entry to α-Substituted Enantiomerically Enriched Nitriles
-
A metal-free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β-cyano esters, α-aryl alkylnitriles, and TBS-protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine).
- Pirola, Margherita,Faverio, Chiara,Orlandi, Manuel,Benaglia, Maurizio
-
supporting information
p. 10247 - 10250
(2021/06/18)
-
- Highly enantioselective construction of CF3-bearing all-carbon quaternary stereocenters: Hiral spiro-fused bisoxazoline ligands with 1,1′-binaphthyl sidearm for asymmetric Michael-type Friedel-Crafts reaction
-
A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was prepared. The developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields (up to 99%) and good to excellent enantioselectivies (up to > 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indole from the Re-face of β-CF3-β-disubstituted nitroalkene was favorable.
- Bao, Robert Li-Yuan,Fu, Kang,Shi, Lei
-
supporting information
(2021/11/27)
-
- Ionic-Liquid Controlled Nitration of Double Bond: Highly Selective Synthesis of Nitrostyrenes and Benzonitriles
-
Unprecedented in literature, the conversion of aryl alkenes into β-nitrostyrenes (2) or benzonitriles (3) with sodium nitrite can be governed by an appropriate choice of ionic liquid (IL) medium. A general trend was found for the selectivity of these processes, which depends on the nature of IL, with imidazolium-based ILs, such as [Bmim]Cl, that favor the C–H nitration leading to β-nitrostyrenes, while tetraalkylammonium-based ILs, such as TBAA, privilege the C=C bond cleavage affording benzonitriles. Besides a substrate scope, mechanistic hypotheses were provided on the origin of the different selectivity in the two kinds of ILs, based on their own tunable properties such as polarity, viscosity, and solvent cage effects.
- Casiello, Michele,Caputo, Daniela,Fusco, Caterina,Cotugno, Pietro,Rizzi, Vito,Dell'Anna, Maria Michela,D'Accolti, Lucia,Nacci, Angelo
-
supporting information
p. 6012 - 6018
(2020/08/24)
-
- Synthetic Diversity from a Versatile and Radical Nitrating Reagent
-
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
-
supporting information
p. 12929 - 12939
(2019/09/17)
-
- Light-Enabled Enantiodivergence: Stereospecific Reduction of Activated Alkenes Using a Single Organocatalyst Enantiomer
-
Light-enabled enantiodivergence is demonstrated in which the alkene substrate configuration is manipulated (E → Z) prior to organocatalytic reduction with a chiral thiourea and Hantzsch ester. This allows stereodivergent reduction to be regulated at the substrate level with high fidelity and mitigates the need for a second, enantiomeric catalyst (up to 93:07 and 95:5 er). The synthetic utility of this strategy has been demonstrated in the synthesis of the weight-loss drug (R)-Lorcaserin (Belviq) and a potent AMPA modulator.
- Hostmann, Theresa,Molloy, John J.,Bussmann, Kathrin,Gilmour, Ryan
-
p. 10164 - 10168
(2019/12/24)
-
- Metal-free, room temperature, acid-K2S2O8 mediated method for the nitration of olefins: An easy approach for the synthesis of nitroolefins
-
Here, we have developed a simple, room temperature method for the nitration of olefins by using inexpensive sodium nitrite as a source of nitro groups in the presence of trifluoroacetic acid (TFA) and potassium persulfate (K2S2O8) under an open atmosphere. Styrenes and mono-substituted olefins give stereo-selective corresponding E-nitroolefins under optimized conditions, however, 1,1-bisubstituted olefins give a mixture of E- and Z-nitroolefins. The optimized conditions work well with electron-donating, electron-withdrawing, un-substituted and heterocyclic styrenes and mono-substituted olefins and give corresponding nitroolefins with good to excellent yields.
- Ambala, Srinivas,Singh, Rohit,Singh, Maninder,Cham, Pankaj Singh,Gupta, Ria,Munagala, Gurunadham,Yempalla, Kushalava Reddy,Vishwakarma, Ram A.,Singh, Parvinder Pal
-
p. 30428 - 30431
(2019/10/04)
-
- Poly(ethylene glycol) supported metal nitrates as well-organized reagents for hunsdiecker conversion of α,β-unsaturated acids to β-nitrostyrenes under solvent and acid-free conditions
-
Poly(ethylene glycol) (PEG) supported metal nitrates such as ferric nitrate and manganese nitrate were accomplished as well-organized reagents for Hunsdiecker conversion of α,β-unsaturated acids to β-nitrostyrenes under acid-free and solvent free conditions using grindstone technique. However, in the case of unsaturated aliphatic acids, nitro alkene derivatives were obtained as products. PEG-400 was found the best among the other PEGs (PEG-200,300, 400, 600, 3000 and 6000) used in this protocol.
- Ramesh,Shylaja,Ramgopal,Rao, A. Sambashiva,Rajanna
-
p. 1798 - 1800
(2019/07/17)
-
- Autoinductive conversion of α,α-diiodonitroalkanes to amides and esters catalysed by iodine byproducts under O2
-
Studies to convert nitroalkanes into amides and esters using I2 and O2 revealed in situ-generated iodine species facilitate the homolytic C-I bond cleavage of α,α-diiodonitroalkanes, arguably in an autoinductive or autocatalytic manner. Consequently, we devised a rapid and economical I2/O2-based method to synthesise sterically hindered esters directly from primary nitroalkanes.
- Li, Jing,Lear, Martin J.,Hayashi, Yujiro
-
supporting information
p. 6360 - 6363
(2018/06/21)
-
- Copper-Promoted Regioselective Synthesis of Polysubstituted Pyrroles from Aldehydes, Amines, and Nitroalkenes via 1,2-Phenyl/Alkyl Migration
-
The facile copper-catalyzed synthesis of polysubstituted pyrroles from aldehydes, amines, and β-nitroalkenes is reported. Remarkably, the use of α-methyl-substituted aldehydes provides efficient access to a series of tetra- and pentasubstituted pyrroles via an overwhelming 1,2-phenyl/alkyl migration. The present methodology is also accessible to non α-substituted aldehydes, yielding the corresponding trisubstituted pyrroles. On the contrary, the use of ketones, in place of aldehydes, does not promote the organic transformation, signifying the necessity of α-substituted aldehydes. The reaction proceeds under mild catalytic conditions with low catalyst loading (0.3-1 mol %), a broad scope, very good functional-group tolerance, and high yields and can be easily scaled up to more than 3 mmol of product, thus highlighting a useful synthetic application of the present catalytic protocol. Based on formal kinetic studies, a possible radical pathway is proposed that involves the formation of an allylic nitrogen radical intermediate, which in turn reacts with the nitroalkene to yield the desired pyrrole framework via a radical 1,2-phenyl or alkyl migration.
- Andreou, Dimitrios,Kallitsakis, Michael G.,Loukopoulos, Edward,Gabriel, Catherine,Kostakis, George E.,Lykakis, Ioannis N.
-
p. 2104 - 2113
(2018/02/23)
-
- Highly Enantioselective Michael Addition of Dithiomalonates to Nitroolefins Catalyzed by New Bifunctional Chiral Thioureas
-
We report a highly efficient asymmetric Michael addition of dithiomalonates to trans -β-nitroole?ns catalyzed by versatile cinchona-based bifunctional thioureas, which provides the corresponding adducts in high yields (up to 92%) and with excellent enanti
- Yuan, Jia-Ni,Liu, Hui-Xia,Tian, Qin-Qin,Ji, Nan,Shen, Kuo,He, Wei
-
supporting information
p. 2577 - 2586
(2018/05/03)
-
- Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
-
Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed “on water” protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the β-position, which might show highly interesting pharmaceutical properties.
- Sim, Jae Hun,Song, Choong Eui
-
p. 1835 - 1839
(2017/02/05)
-
- In order to iodide is one pot synthesis nitryl source α, β - unsaturated nitro olefin derivatives (by machine translation)
-
The present invention discloses a one-pot synthesis nitryl source iodide is α, β - unsaturated nitro olefin derivatives, vinyl compounds containing four aryl ferrous (III), iodide and tertiary-butyl hydrogen peroxide in acetonitrile solution system a pot of reaction, generating α, β - unsaturated nitro olefin derivatives; the method to achieve the under mild reaction conditions, high yield with high stereo selectivity of the E synthesis of α, β - unsaturated nitro olefin. (by machine translation)
- -
-
Paragraph 0122-0128
(2017/09/01)
-
- Α, β - unsaturated nitro olefin derivative synthesis method (by machine translation)
-
The invention discloses a α, β - unsaturated nitro olefin derivative synthesis method, vinyl compounds containing four aryl ferrous (III), ammonium halide and tertiary-butyl hydrogen peroxide in the system of the one-pot reaction, generating α, β - unsaturated nitro olefin derivatives; the method to achieve the under mild reaction conditions, high yield with high stereo selectivity of the E synthesis of α, β - unsaturated nitro olefin. (by machine translation)
- -
-
Paragraph 0027; 0034; 0126; 0127; 0128; 0129
(2017/09/05)
-
- Substrate Scope Evaluation of the Enantioselective Reduction of β-Alkyl-β-arylnitroalkenes by Old Yellow Enzymes 1-3 for Organic Synthesis Applications
-
The substrate scope of the old yellow enzyme catalyzed reduction of β-alkyl-β-arylnitroalkenes is investigated. Compounds bearing either alkyl chains of increasing length at the carbon atom in position β to the nitro group or different substituents on the aromatic ring are prepared and submitted to bioreduction, to define the synthetic potential of this enantioselective reaction in the preparation of chiral fine chemicals. The versatility of the resulting nitroalkanes as chiral building blocks is shown by reducing the nitro group into a primary amine and by converting it into a carboxylic acid moiety by Meyer reaction. An "explosion" of chiral products can be observed by combining the highly enantioselective ene-reductase-mediated reduction of nitroalkenes with the chemical versatility of the nitro group.
- Bertolotti, Mattia,Brenna, Elisabetta,Crotti, Michele,Gatti, Francesco G.,Monti, Daniela,Parmeggiani, Fabio,Santangelo, Sara
-
p. 577 - 583
(2016/02/23)
-
- K2S2O8-mediated nitration of alkenes with NaNO2 and 2,2,6,6-tetramethylpiperidine-1-oxyl: Stereoselective synthesis of (E)-nitroalkenes
-
A transition-metal-free nitration of alkenes with NaNO2 in the presence of K2S2O8 and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is developed. The transformation exhibits a broad substrate scope and good functional group tolerance, thus providing a new and expedient protocol for stereoselective synthesis of (E)-nitroalkenes with moderate to good yields. Moreover, the nitration processes of (E)- and (Z)-stilbene are also studied: even though the proportion of substrates is different, the E/Z ratio of the products is basically the same. Based upon experimental observations, a possible reaction mechanism is proposed.
- Zhao, An,Jiang, Qing,Jia, Jing,Xu, Bin,Liu, Yufeng,Zhang, Mingzhong,Liu, Qiang,Luo, Weiping,Guo, Cancheng
-
supporting information
p. 80 - 84
(2015/12/23)
-
- Enantioselective iridium-catalyzed hydrogenation of β,β-disubstituted nitroalkenes
-
An iridium complex with a newly prepared chiral spiro amino-phosphine ligand efficiently catalyzed the hydrogenation of both β-aryl-β-methyl-nitroalkenes and β-alkyl-β-methyl-nitroalkenes to the corresponding saturated nitroalkanes, which represents the f
- Yu, Yan-Bo,Cheng, Lei,Li, Yi-Pan,Fu, Yue,Zhu, Shou-Fei,Zhou, Qi-Lin
-
supporting information
p. 4812 - 4815
(2016/04/09)
-
- Iridium-Catalyzed Enantioselective Hydrogenation of β,β-Disubstituted Nitroalkenes
-
A highly efficient, iridium-catalyzed, enantioselective hydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000).
- Liu, Man,Kong, Duanyang,Li, Meina,Zi, Guofu,Hou, Guohua
-
p. 3875 - 3879
(2016/01/25)
-
- 1,4-addition of TMSCCl3 to nitroalkenes: Efficient reaction conditions and mechanistic understanding
-
Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4-additions to a range of cyclic and acyclic nitroalkenes, in THF at 0-25 °C, typically in moderate to excellent yields (37-95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (1H, 19F, 13C and 29Si) under anaerobic conditions indicate that addition of TMSCCl3 to TBAT (both 0.13 M) at -20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me3SiF, Ph3SiF and NBu4CCl3. The latter is stable to at least 0 °C and does not add nitroalkene from -20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl3 (both 0.13 M at -20 °C), when treated with TBAT, leads to immediate formation of the 1,4-addition product, suggesting the reaction proceeds via a transient [Me 3Si(alkene)CCl3] species, in which (alkene) indicates an Si O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3 - addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2=NO2] is an efficient promoter. Use of H2C=CH(CH2)2CH=CHNO 2 in air affords radical-derived bicyclic products arising from aerobic oxidation. Understanding TMSCCl3: The synthesis and reactivity of TMSCCl3 has been investigated. The mechanism of 1,4-CCl3 addition to nitroalkenes begins with nitroalkene coordination, followed by the attack of an external fluoride ion, and does not involve the formation of NBu4[Me3SiFCCl3] (see figure).
- Wu, Na,Wahl, Benoit,Woodward, Simon,Lewis, William
-
p. 7718 - 7724
(2014/07/07)
-
- Clay-supported copper nitrate (claycop): A mild reagent for the selective nitration of aromatic olefins
-
A straightforward and highly selective method has been developed for the nitration of a wide variety of aromatic and aliphatic olefins by using a clay-supported copper nitrate (Claycop) and a catalytic amount of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, an inexpensive and mild reagent system. High conversions and exclusive E-selectivity, together with the environmentally benign nature of the Claycop reagent, make this a green method and an attractive alternative to established methods. Georg Thieme Verlag Stuttgart. New York.
- Begari, Eeshwaraiah,Singh, Chandani,Nookaraju,Kumar, Pradeep
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p. 1997 - 2000
(2014/11/08)
-
- Synthesis of substituted nitroolefins: A copper catalyzed nitrodecarboxylation of unsaturated carboxylic acids
-
A novel, mild and convenient method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their nitroolefins is achieved using a catalytic amount of CuCl (10 mol%) and tert-butyl nitrite (2 equiv.) as a nitrating agent in the presence of air. This reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives, which are generally difficult to access from other conventional methods. Additionally, this reaction is selective as the E-isomer of the acid derivatives furnishes the corresponding E-nitroolefins. One more salient feature of the method is, unlike other methods, no metal nitrates or HNO3 are employed for the transformation.
- Rokade, Balaji V.,Prabhu, Kandikere Ramaiah
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p. 6713 - 6716
(2013/10/01)
-
- Efficient and stereoselective nitration of mono- and disubstituted olefins with AgNO2 and TEMPO
-
Nitroolefin is a common and versatile reagent. Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds. Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins. This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner.
- Maity, Soham,Manna, Srimanta,Rana, Sujoy,Naveen, Togati,Mallick, Arijit,Maiti, Debabrata
-
supporting information
p. 3355 - 3358
(2013/04/10)
-
- Tertiary amine functionalized polyacrylonitrile fiber catalyst for the synthesis of tetrahydrothiophenes
-
A tertiary amine immobilized fiber was prepared and used to efficiently catalyze tandem Michael-intramolecular Henry reactions between 1,4-dithiane-2,5-diol and trans-β-nitrostyrenes to form the corresponding tetrahydrothiophene derivatives. This newly developed fiber catalyst is applicable to a wide range of trans-β-nitroalkenes and affords good to excellent yields (75-93%) under mild conditions (with 2.5 mol % fiber catalyst at 50 °C in ethanol for 5 h). The fiber catalyst exhibits excellent recyclability and reusability (up to 10 times) after simple workup procedure with only a slight loss in catalytic activity. It is noteworthy that the major diastereomers have r-R, trans-nitro, trans-hydroxy configurations with diastereoselectivities of up to 15:1. This differs from the results obtained when the same reaction is catalyzed by a homogeneous catalyst. This is the first example of a fiber catalyst exhibiting excellent diastereoselectivity.
- Xu, Changzhu,Du, Jianguo,Ma, Lichao,Li, Guowei,Tao, Minli,Zhang, Wenqin
-
supporting information
p. 4749 - 4757
(2013/06/27)
-
- A predictably selective nitration of olefin with Fe(NO3) 3 and TEMPO
-
Ferric nitrate with catalytic TEMPO has been identified as a useful reagent for regio- and stereoselective nitration of a wide variety of aromatic, aliphatic, and heteroaromatic olefins. This reaction provided nitroolefins in preparatively useful yields with excellent E-selectivity. Due to its mild nature and operational simplicity, the present protocol is expected to find application in synthetic setup.
- Naveen, Togati,Maity, Soham,Sharma, Upendra,Maiti, Debabrata
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p. 5949 - 5954
(2013/07/26)
-
- Highly substituted enantioenriched cyclopentane derivatives by palladium-catalyzed [3 + 2] trimethylenemethane cycloadditions with disubstituted nitroalkenes
-
β,β-Disubstituted nitroalkenes readily undergo palladium-catalyzed [3 + 2] cycloaddition with trimethylenemethane to generate nitrocyclopentanes in excellent yield and enantioselectivity. The reaction provides access to heavily substituted cyclopentanes c
- Trost, Barry M.,Bringley, Dustin A.,O'Keefe, B. Michael
-
supporting information
p. 5630 - 5633
(2013/12/04)
-
- Rh-catalyzed highly enantioselective hydrogenation of nitroalkenes under basic conditions
-
Go catalytic! A highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes and isomeric mixtures of nitroalkenes by using a Rh/DuanPhos catalytic system under basic conditions has furnished a convenient approach to β-chiral nitroalkanes, whic
- Li, Shengkun,Huang, Kexuan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
-
supporting information
p. 10840 - 10844
(2013/09/02)
-
- Highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes
-
Building the building blocks: A highly enantioselective hydrogenation of ?-aryl-?-alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomerically pure nitroalkanes 2, which are versatile precursors for chemical synthesis.
- Li, Shengkun,Huang, Kexuan,Cao, Bonan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
-
p. 8573 - 8576
(2012/09/10)
-
- Readily available hydrogen bond catalysts for the asymmetric transfer hydrogenation of nitroolefins
-
This paper focuses on readily accessible thiourea hydrogen bond catalysts derived from amino acids, whose steric and electronic features are modulated by their degree of substitution at the carbinol carbon center. These catalysts were applied in the asymmetric transfer hydrogenation of nitroolefins furnishing the chiral products in up to 99% yield and 86% enantiomeric excess. The proposed catalyst's mode of action is supported by mechanistic investigations.
- Schneider, Jakob F.,Lauber, Markus B.,Muhr, Vanessa,Kratzer, Domenic,Paradies, Jan
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p. 4323 - 4327
(2011/07/08)
-
- Reductive biotransformation of nitroalkenes via nitroso-intermediates to oxazetes catalyzed by xenobiotic reductase A (XenA)
-
A novel reductive biotransformation pathway for β,β-disubstituted nitroalkenes catalyzed by flavoproteins from the Old Yellow Enzyme (OYE) family was elucidated. It was shown to proceed via enzymatic reduction of the nitro-moiety to furnish the corresponding nitroso-alkene, which underwent spontaneous (non-enzymatic) electrocyclization to form highly strained 1,2-oxazete derivatives. At elevated temperatures the latter lost HCN via a retro-[2 + 2]-cycloaddition to form the corresponding ketones. This pathway was particularly dominant using xenobiotic reductase A, while pentaerythritol tetranitrate-reductase predominantly catalyzed the biodegradation via the Nef-pathway.
- Durchschein, Katharina,Fabian, Walter M. F.,MacHeroux, Peter,Zangger, Klaus,Trimmel, Gregor,Faber, Kurt
-
p. 3364 - 3369
(2011/06/25)
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- Versatile synthesis of α-substituted taurines from nitroolefins
-
A series of 1-substituted and 1,1-disubstituted taurines were synthesized from nitroolefins via the Michael addition with sodium ethylxanthate, oxidation with performic acid, and reduction with hydrogen in the presence of palladium on carbon powder. The current route is a versatile and salt-free method for synthesis of both aliphatic and aromatic 1-substituted and 1,1-disubstituted taurines. Springer-Verlag 2010.
- Xu, Chuanxiang,Xu, Jiaxi
-
scheme or table
p. 195 - 203
(2012/04/10)
-
- The flavoprotein-catalyzed reduction of aliphatic nitro-compounds represents a biocatalytic equivalent to the Nef-reaction
-
The bioreduction of aliphatic sec-nitro compounds catalyzed by purified flavoproteins from the old-yellow-enzyme family unexpectedly furnished the corresponding carbonyl compounds instead of the expected amines and thus represents a biocatalytic equivalent to the Nef-reaction. The pathway was shown to proceed via initial reduction of the nitro-group to yield the nitroso-derivative, which spontaneously tautomerized to yield the more stable oxime, which was enzymatically reduced in a second step to furnish a hydrolytically unstable imine-species, which spontaneously hydrolyzed to finally give a carbonyl compound and ammonia.
- Durchschein, Katharina,Ferreira-Da Silva, Bianca,Wallner, Silvia,MacHeroux, Peter,Kroutil, Wolfgang,Glueck, Silvia Maria,Faber, Kurt
-
supporting information; experimental part
p. 616 - 619
(2010/09/05)
-
- Iron-mediated radical halo-nitration of alkenes
-
Radical halo-nitration of alkenes using iron(III) nitrate nonahydrate and halogen salt has been developed. The present reaction proceeds by radical addition of nitrogen dioxide generated by thermal decomposition of iron(III) nitrate nonahydrate and subsequent trapping of the resultant radical by a halogen atom in the presence of halogen salt. Application of this method to synthesis of nitroalkenes is also described. The practicality of the present method using nontoxic and inexpensive iron reagents has been shown by the application to broad alkenes.
- Taniguchi, Tsuyoshi,Fujii, Tatsuya,Ishibashi, Hiroyuki
-
scheme or table
p. 8126 - 8132
(2011/03/17)
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- Highly enantioselective reduction of β,β-disubstituted aromatic nitroalkenes catalyzed by Clostridium sporogenes
-
(Chemical Equation Presented) This is the first report of the use of Clostridium sporogenes extracts for enantioselective reduction of C=C double bonds of β,β-disubstituted (1) and α,β-disubstituted nitroalkenes (3). Crude enzyme preparations reduced aryl derivatives 1a-e and 1h, in 35-86% yield with ≥97% ee. Reduction of (E)- and (Z)-isomers of 1c gave the same enantiomer of 2c (≥99% ee). In contrast, α,β- disubstituted nitroalkene 3a was a poor substrate, yielding (S)-4a in low yield (10-20%), and the ee (30-70% ee) depended on NADH concentration. An efficient synthesis of a library of nitroalkenes 1 is described.
- Fryszkowska, Anna,Fisher, Karl,Gardiner, John M.,Stephens, Gill M.
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p. 4295 - 4298
(2008/12/20)
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- Asymmetric bioreduction of activated C=C bonds using Zymomonas mobilis NCR enoate reductase and old yellow enzymes OYE 1-3 from yeasts
-
The asymmetric bioreduction of C=C-bonds bearing an electron-withdrawing group, such as an aldehyde, ketone, imide, nitro, carboxylic acid, or ester moiety by a novel enoate reductase from Zymomonas mobilis and Old Yellow Enzymes OYE 1-3 from yeasts furnished the corresponding saturated products in up to >99%ee. Depending on the substrate type, stereocontrol was achieved by variation of the substrate structure, by switching the (E/Z) geometry of the alkene or by choice of the appropriate enzyme. This substrate- or enzyme-based stereocontrol allowed access to the opposite enantiomeric products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Hall, Melanie,Stueckler, Clemens,Hauer, Bernhard,Stuermer, Rainer,Friedrich, Thomas,Breuer, Michael,Kroutil, Wolfgang,Faber, Kurt
-
supporting information; experimental part
p. 1511 - 1516
(2009/04/11)
-
- A selective and practical synthesis of nitroolefins
-
A straightforward and general synthesis of nitroolefins from nitric oxide (NO) and olefins is presented. The direct nitration of aromatic olefins, allyl compounds, and acrylic acid derivatives proceeds smoothly at room temperature with high regioselectivity and good yields. The advantages of this novel procedure compared to established nitration procedures are demonstrated.
- Jovel, Irina,Prateeptongkum, Saisuree,Jackstell, Ralf,Vogl, Nadine,Weckbecker, Christoph,Beller, Matthias
-
experimental part
p. 2493 - 2497
(2009/08/14)
-
- Asymmetric bioreduction of C=C bonds using enoate reductases OPR1, OPR3 and YqjM: Enzyme-based stereocontrol
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Three cloned enoate reductases from the "old yellow enzyme" family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing α,β-unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity-only the conjugated C=C bond was reduced, while isolated olefins and carbonyl groups remained intact-with excellent stereoselectivities (ees up to >99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this "enzyme-based stereocontrol" is caused by subtle differences within the active site geometries.
- Hall, Melanie,Stueckler, Clemens,Ehammer, Heidemarie,Pointner, Eva,Oberdorfer, Gustav,Gruber, Karl,Hauer, Bernard,Stuermer, Rainer,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
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experimental part
p. 411 - 418
(2009/04/10)
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- Structure-based insight into the asymmetric bioreduction of the C=C double bond of α,β-unsaturated nitroalkenes by pentaerythritol tetranitrate reductase
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Biocatalytic reduction of α- or β-alkyl-barylnitroalkenes provides a convenient and efficient method to prepare chiral substituted nitroalkanes. Pentaerythritol tetranitrate reductase (PETN reductase) from Enterobacter cloacae st. PB2 catalyses the reduction of nitroolefins such as 1-nitrocyclohexene (1) with steady state and rapid reaction kinetics comparable to other old yellow enzyme homologues. Furthermore, it reduces 2-aryl-1-nitropropenes (4a-d) to their equivalent (S)-nitropropanes 9a-d. The enzyme shows a preference for the (Z)-isomer of substrates 4a-d, providing almost pure enantiomeric products 9a-d (ees up to > 99%) in quantitative yield, whereas the respective (E)-isomers are reduced with lower enantioselectivity (63-89% ee) and lower product yields. 1-Aryl-2-nitropropenes (5a, b) are also reduced efficiently, but the products (R)-10 have lower optical purities. The structure of the enzyme complex with 1-nitrocyclohexene (1) was determined by X-ray crystallography, revealing two substrate-binding modes, with only one compatible with hydride transfer. Models of nitropropenes 4 and 5 in the active site of PETN reductase predicted that the enantioselectivity of the reaction was dependent on the orientation of binding of the (E)- and (Z)- substrates. This work provides a structural basis for understanding the mechanism of asymmetric bioreduction of nitroalkenes by PETN reductase.
- Toogood, Helen S.,Fryszkowska, Anna,Hare, Victoria,Fisher, Karl,Roujeinikova, Anna,Leys, David,Gardiner, John M.,Stephens, Gill M.,Scrutton, Nigel S.
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experimental part
p. 2789 - 2803
(2009/10/20)
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- Organocatalytic asymmetric transfer hydrogenation of nitroolefins
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We describe a highly efficient and highly enantioselective Hantzsch ester mediated conjugate transfer hydrogenation of β,β-disubstituted nitroolefins that is catalyzed by a Jacobsen-type thiourea catalyst. Copyright
- Martin, Nolwenn J. A.,Ozores, Lidia,List, Benjamin
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p. 8976 - 8977
(2008/02/10)
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- Asymmetric bioreduction of activated alkenes using cloned 12-oxophytodienoate reductase isoenzymes OPR-1 and OPR-3 from Lycopersicon esculentum (tomato): A striking change of stereoselectivity
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(Chemical Equation Presented) Tomato source: 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from tomato possess a broad substrate spectrum for the asymmetric bioreduction of α,β-unsaturated enals, enones, dicarboxylic acids, and N-substituted male-imides (see scheme). Stereocomplementary behavior of both isoenzymes was observed in the reduction of a nitroalkene that led to the formation of opposite stereoisomers in high enantiomeric excess.
- Hall, Melanie,Stueckler, Clemens,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
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p. 3934 - 3937
(2008/03/11)
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- Optically active nitrile oxides: synthesis and 1,3-dipolar cycloaddition reactions
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Baker's yeast-promoted reduction of the C{double bond, long}C bond in 2-aryl-1-nitropropenes gave the corresponding optically active (R)-2-aryl-1-nitropropanes of high enantiomeric purity (ee >90%). They were next converted with the aid of the Mukaiyama and Hoshino method into the optically active nitrile oxides, which were made to react in situ with ethyl propiolate, methylvinyl ketone and (R)-1-phenyl-2-(phenylsulfonyl)ethyl acrylate to yield the appropriate, enantiomerically enriched, isoxazoles or 4,5-dihydroisoxazoles as diastereomeric mixtures, respectively.
- Zagozda, Marcin,Plenkiewicz, Jan
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p. 1457 - 1464
(2008/02/11)
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- Metal nitrate driven nitro Hunsdiecker reaction with α,β-unsaturated carboxylic acids under solvent-free conditions
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Hunsdiecker reactions with α,β-unsaturated carboxylic acids were conducted under solvent-free conditions in the presence of a few drops of HNO3 together with a variety of metal nitrates [Mg(NO3)2, Sr(NO3)2], Al(NO3)3, Ca(NO3)2, Ni(NO3)2, Cd(NO3)2, Zn(NO3)2, Hg(NO3)2, AgNO3, ZrO(NO3)2, UO2(NO3)2, Th(NO3)2] or ammonium nitrate. α,β-Unsaturated aromatic carboxylic acids underwent nitro decarboxylation to afford β-nitro styrenes in moderate to good yields, while α,β-unsaturated aliphatic carboxylic acids underwent decarboxylation to yield the corresponding nitro derivatives.
- Ramgopal,Ramesh,Chakradhar,Reddy, N. Maasi,Rajanna
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p. 4043 - 4045
(2008/02/04)
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- Enantioselective synthesis of nitroalkanes bearing all-carbon quaternary stereogenic centers through Cu-catalyzed asymmetric conjugate additions
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The first examples of catalytic asymmetric conjugate addition (ACA) of alkylzinc reagents to trisubstituted nitroalkenes, leading to the formation of nitroalkanes bearing a quaternary carbon stereogenic center, are reported. Reactions are promoted in the
- Wu, Jing,Mampreian, Dawn M.,Hoveyda, Amir H.
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p. 4584 - 4585
(2007/10/03)
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- A one-pot, two step synthesis of 2,2-disubstituted 1-nitroalkenes
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The reactions of ketones 1a-o, nitromethane 2, and a stoichiometric amount of piperidine 3a or ethylenediamine 3b in the presence of mercaptan 6a in THF or CH3CN solution give high yields of β-nitrosulfides 7a-o. The latter can be oxidized by 8
- Jang, Yeong-Jiunn,Lin, Wen-Wei,Shih, Yuh-Kuo,Liu, Ju-Tsung,Hwang, Ming-Hsing,Yao, Ching-Fa
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p. 4979 - 4992
(2007/10/03)
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- Microwave-induced solvent-free, rapid and efficient synthesis of conjugated nitroalkenes using sulfated zirconia
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Sulfated Zirconia catalyzed synthesis of conjugated nitroalkenes has been carrried out under solvent-free condition using sulfated zirconia. Recyclability of catalyst, isolation of pure products by simple filtration and evaporation are important features of this method.
- Bandgar,Kasture
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p. 1239 - 1241
(2007/10/03)
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- One-pot selective synthesis of β-nitrostyrenes from styrenes, promoted by Cu(II)
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A convenient, inexpensive and efficient 'one-pot' process is described for the selective nitration of styrenes to the corresponding β-nitrostyrenes under mild conditions. The procedure tolerates such functional groups as alkyl, aryl, alkoxy, acyloxy and chlorine on the aromatic ring and can be applied to derivatives substituted on the vinyl group. (C) 2000 Elsevier Science Ltd.
- Campos, Pedro J.,García, Bárbara,Rodríguez, Miguel A.
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p. 979 - 982
(2007/10/03)
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- Gel entrapped base catalysed (GEBC) Henry reaction: Synthesis of conjugated nitroalkenes
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A new, simple and practical procedure for direct transformation of aldehydes or ketones and nitromethane into conjugated nitroalkenes by using novel gel entrapped base catalyst (GEBC) has been described.
- Bandgar,Uppalla
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p. 2071 - 2075
(2007/10/03)
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- Generation and cycloaddition reactions of substituted 2-nitro-1,3-dienes
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4-Acyloxy-2-substituted-3-nitro-1-butenes have been utilized as convenient precursors of the corresponding 2-nitro-3-substituted-1,3-butadienes which could be easily generated in situ by heating or by treatment with sodium acetate and trapped by suitable
- Barco, Achille,Benetti, Simonetta,De Risi, Carmela,Morelli, Carlo F.,Pollini, Gian P.,Zanirato, Vinicio
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p. 9275 - 9288
(2007/10/03)
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- Potential GABAB Receptor Antagonists. VII. The Synthesis of 2-(4-Chlorophenyl)-3-nitropropan-1-amine and Related Analogues of Baclofen
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3-Nitro-2-phenylpropan-1-amine and 2-(4-chlorophenyl)-3-nitropropan-1-amine have been synthesized by the addition of nitrous acid to the corresponding trifluoroacetylaminomethylstyrenes followed by reduction of the double bond with sodium borohydride.A more general and efficient route involves the Michael addition of nitroalkane anions to methyl cinnamates followed by Curtius degradation of the corresponding acids. 2-(4-Chlorophenyl)-3-nitropropan-1-amine is a specific agonist of GABA and the GABAB receptor, with about half the activity of racemic baclofen at the isolated guinea pig ileum.Methylation or dimethylation at C3 decreases activity markedly.
- Abbenante, Giovanni,Hughes, Robert,Prager, Rolf H.
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p. 1441 - 1452
(2007/10/02)
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- Asymmetric Reduction of Nitro Olefins by Fermenting Bakers' Yeast
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Reduction of a number of 1-nitro-1-alkenes by fermenting bakers' yeast has been found to be enantioselective, resulting in the formation of optically active 1-nitroalkanes.In most cases, optical purities of the products determined by HPLC analysis of MTPA amides were as high as 83-98percent ee.The optimum rate of conversion was obtained when the reaction was carried out at pH 8 and low concentration of substrates.The absolute configuration of resulting (+)-1-nitro-2-phenylpropane was determined to be R by comparing the specific rotation with that of an authentic specimen after reductive hydrolysis to the corresponding aldehyde.
- Ohta, Hiromichi,Kobayashi, Naoki,Ozaki, Kazuhiko
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p. 1802 - 1804
(2007/10/02)
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