- Synthesis of unsaturated silyl nitronates via the silylation of conjugated nitroalkenes
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A new method for the synthesis of conjugated silyl nitronates from nitroalkenes is described. The procedure has wide substrate scope and is compatible with in situ generation of the substrates from 2-nitroalcohols or 2-chloro-nitroalkanes. A cascade transformation to give 3,4,5,6-tetrahydropyridine N-oxide derivatives was disclosed.
- Khotyantseva, Elizaveta A.,Tabolin, Andrey A.,Novikov, Roman A.,Nelyubina, Yulia V.,Ioffe, Sema L.
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supporting information
p. 3128 - 3131
(2018/07/13)
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- Insights into the diastereoselective control in the sulfa-Michael addition of thiols to nitroalkenes: Stereoelectronic effect in the cyclic chelated transition state
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The diastereoselective control in the sulfa-Michael addition of nitroalkenes and lithium thiolates followed by protonation was investigated. Lithium thiolates first added to nitroalkenes to afford cyclic lithium-chelated nitronates. The subsequent kinetic protonation of nitronates was proved to be the stereochemical determinant through the chelate-controlled six-membered half-chair transition state bearing two approximately 1,2-diaxial substituents due to stereoelectronic effect control. The stereoelectronic effect in the cyclic chelated transition state was probed and verified by tuning the steric bulkiness of the corresponding substituents. The reaction involving 1-nitrocyclohexene provided perfect support for the proposed diastereoselective control model. The current investigation provided not only comprehensive insights into the diastereoselective control in the sulfa-Michael addition of nitroalkenes and thiolates, but also an important role of the stereoelectronic effect in certain organic reactions involving cyclic chelate transition states.
- Wang, Jiandong,Li, Pingfan,Yang, Zhanhui,Chen, Ning,Xu, Jiaxi
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p. 370 - 378
(2015/12/31)
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- Synthesis and characterization of Piperidine-4-carboxylic acid functionalized Fe3O4 nanoparticles as a magnetic catalyst for Knoevenagel reaction
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Piperidine-4-carboxylic acid (PPCA) functionalized Fe3O 4 nanoparticles as a novel organic-inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe3O4, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10 nm), TEM (11 nm) and magnetization fitting (9 nm) agree well, revealing nearly single crystalline character of Fe 3O4 nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe3O4 NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe 3O4-PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH2Cl2 at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.
- Karaoglu,Baykal,?enel,S?zeri,Toprak
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experimental part
p. 2480 - 2486
(2012/10/08)
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- Chemo-enzymatic synthesis of a multi-useful chiral building block molecule for the synthesis of medicinal compounds
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Optical resolution of 2-methyl-2-nitrobut-3-en-1-ol has been accomplished using a low-temperature lipase-catalyzed transesterification carried out at -40°C.
- Nakano, Toshiki,Yagi, Yusuke,Miyahara, Mizuki,Kaminura, Akio,Kawatsura, Motoi,Itoh, Toshiyuki
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experimental part
p. 6747 - 6757
(2011/10/18)
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- A convenient procedure for the synthesis of 3-substituted 5,6-dihydro-4H-1,2-oxazines from nitroethane
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A novel and efficient four-step procedure for the synthesis of C-3-functionalised 5,6-dihydro-4H-1,2-oxazines from nitroethane is described. It includes preparation of 3-methyl-substituted six-membered cyclic nitronates, 3-(bromomethyl)-substituted 5,6-dihydro-4H-1,2-oxazines as intermediates, and nucleophilic substitution of bromine. Total yields of the target C-3-functionalised oxazines are 15-30% from nitroethane. Georg Thieme Verlag Stuttgart.
- Sukhorukov, Alexey Yu.,Klenov, Michael S.,Ivashkin, Pavel E.,Lesiv, Alexey V.,Khomutova, Yulya A.,Ioffe, Sema L.
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- Diastereoselective access to 3-nitro-4-vinylidenetetrahydrofurans and 3-nitro-4-vinylidenetetrahydropyrans and their conversion into 3,6-dihydro-1,2-oxazines by reverse cope elimination of hydroxylamine precursors
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A new approach to the synthesis of unsaturated nitro-allenyltetrahydrofurans 3 and -tetrahydropyrans 5 has been developed, involving oxa-Michael addition/SN2′ substitution of propargyl and homopropargyl alcohol derivatives 2a and 4h on nitroalkenes1a-g. Complete allylic 1,3-strain control during the cyclization accounts for the observed diastereoselectivity. Reduction of nitro compounds 3 and 5 with SmI2 provided new α-allenylhydroxylamines 7 and 8, which were easily isomerized into 3,6-dihydro-1,2-oxazines 9 and 10 by reverse Cope elimination. Wiley-VCH Verlag GmbH, 2001.
- Dumez, Estelle,Faure, Robert,Dulcere, Jean-Pierre
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p. 2577 - 2588
(2007/10/03)
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- Enantioselective synthesis of α,α-disubstituted amines from nitroalkenes
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Disubstituted nitroalkenes were converted into enantiomerically enriched amines (isolated as their hydrochloride salts) with enantiometric excesses of 88 to >95% in there steps: (a) highly stereoselective conjugate addition of the potassium salt of 4-phenyloxazolidin-2-one; (b) radical-mediated removal of the nitro group; (c) cleavage of the oxazolidinone.
- Leroux, Mary-Lorene,Le Gall, Thierry,Mioskowski, Charles
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p. 1817 - 1823
(2007/10/03)
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- A New Method for the Preparation of Conjugated Nitro Olefins
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Condensation of 1-nitroalkanephosphonates with carbonyl compounds affords a new and facile method for the preparation of conjugated nitro olefins.
- Fujii, Masayuki
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p. 933 - 934
(2007/10/02)
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- Reactions of O,O-Diprotonated Nitro Olefins with Benzenes. Formations of Phenylacetones, 4H-1,2-Benzoxazines and Biarylacetone Oximes
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O,O-Diprotonated nitro olefins undergo three alternative electrophilic reactions which yield α-phenylacetones, 4H-1,2-benzoxazines and biphenylacetone oximes depending on the reaction conditions (temperature and time) and aromatic substrates.Although these reactions are seemingly divergent, a common intermediate of a phenylated protonated aci-nitro species, derived from the dication, is postulated to be involved in the reactions.Furthermore, the formation of benzoxazines and biphenylacetone oximes can be interpreted in terms of participation of novel chemical species with phenylethylene dication character derived from the common intermediate.
- Ohwada, Tomohiko,Okabe, Kazuaki,Ohta, Toshiharu,Shudo, Koichi
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p. 7539 - 7555
(2007/10/02)
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- Cycloadditions dipolaires 1,3 aux derives nitres α ethyleniques, acetyleniques potentiels. I. Reaction avec des ylures d'azomethine. Orientation et stereochimie de la cycloaddition
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The stereochemistry of the nitroolefins 1 prepared by known methods was unambigously established.Their reactions with azomethine ylides (e.g. 8) was studied and the stereochemistry of the adducts as well.This preliminary work was necessary to substantiate a discussion of structural (pyrrolidines conformational analysis) and mechanistic problems (dipolarophile-azomethine ylide approach and HNO2 elimination from the nitro pyrrolidines).
- Benhaoua, Hadj,Piet, Jean-Claude,Danion-Bougot, Renee,Toupet, Loic,Carrie, Robert
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p. 325 - 338
(2007/10/02)
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