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10 results on '"Andrey A. Tabolin"'

1. Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

Author

Savva A. Ponomarev, Roman V. Larkovich, Alexander S. Aldoshin, Andrey A. Tabolin, Sema L. Ioffe, Jonathan Groß, Till Opatz, and Valentine G. Nenajdenko

Subjects
diels–alder reaction, fluorine, nitrostyrene, norbornene, stereochemistry, Science, Organic chemistry, QD241-441
Abstract

The Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic 1,3-dienes was investigated. A series of novel monofluorinated norbornenes was prepared in up to 97% yield. The reaction with 1,3-cyclohexadiene permits the preparation of monofluorinated bicyclo[2.2.2]oct-2-enes. The kinetic data of the reactions with 1,3-cyclopentadiene and 1,3-cyclohexadiene were used to calculate activation parameters. Furthermore, the synthetic utility of the cycloadducts obtained was demonstrated.

Published
2021
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2. [3+3]-Annulation of Cyclic Nitronates with Vinyl Diazoacetates: Diastereoselective Synthesis of Partially Saturated [1,2]Oxazino[2,3-b][1,2]oxazines and Their Base-Promoted Ring Contraction to Pyrrolo[1,2-b][1,2]oxazine Derivatives

Author

Yulia A. Antonova, Yulia V. Nelyubina, Sema L. Ioffe, and Andrey A. Tabolin

Subjects
[3+3]-annulation, diazo compounds, nitronates, 1,2-oxazines, pyrroles, rhodium carbenoids, Organic chemistry, QD241-441
Abstract

A rhodium(II)-catalyzed reaction of cyclic nitronates (5,6-dihydro-4H-1,2-oxazine N-oxides) with vinyl diazoacetates proceeds as a [3+3]-annulation producing bicyclic unsaturated nitroso acetals (4a,5,6,7-tetrahydro-2H-[1,2]oxazino[2,3-b][1,2]oxazines). Optimization of reaction conditions revealed the use of Rh(II) octanoate as the preferred catalyst in THF at room temperature, which allows the preparation of target products in good yields and excellent diastereoselectivity. Under basic conditions, namely, the combined action of DBU and alcohol, these nitroso acetals undergo ring contraction of an unsaturated oxazine ring into the corresponding pyrrole. Both transformations can be performed in a one-pot fashion, thus constituting a quick approach to oxazine-annulated pyrroles from available starting materials, such as nitroalkenes, olefins, and diazo compounds.

Published
2023
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3. An Easy Synthesis of Monofluorinated Derivatives of Pyrroles from β-Fluoro-β-Nitrostyrenes

Author

Alexander S. Aldoshin, Andrey A. Tabolin, Sema L. Ioffe, and Valentine G. Nenajdenko

Subjects
β-Fluoro-β-nitrostyrene, vinylpyrrole, Michael addition, elimination, kinetics, Hammett equation, Organic chemistry, QD241-441
Abstract

The catalyst-free conjugate addition of pyrroles to β-Fluoro-β-nitrostyrenes was investigated. The reaction was found to proceed under solvent-free conditions to form 2-(2-Fluoro-2-nitro-1-arylethyl)-1H-pyrroles. The effectiveness of this approach was demonstrated through the preparation of a series of the target products in a quantitative yield. The kinetics of a conjugate addition of pyrrole was studied in detail to reveal the substituent effect and activation parameters of the reaction. The subsequent base-induced elimination of nitrous acid afforded a series of novel 2-(2-Fluoro-1-arylvinyl)-1H-pyrroles prepared in up to an 85% isolated yield. The two-step sequence herein proposed is an indispensable alternative to a direct reaction with elusive and unstable 1-Fluoroacetylenes.

Published
2021
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5. Oxidative [3+2]-annulation of nitroalkenes and azolium ylides in the presence of Cu(<scp>ii</scp>): efficient synthesis of [5,5]-annulated N-fused heterocycles

Author

Andrey A. Tabolin, Sema L. Ioffe, and Vladimir A. Motornov

Subjects
Annulation, Chemistry, Fluorinated derivatives, Materials Chemistry, chemistry.chemical_element, Oxidative phosphorylation, General Chemistry, Copper, Medicinal chemistry, Catalysis
Abstract

A facile synthesis of [5,5]-annulated N-fused heterocycles – pyrrolo[2,1-b]thiazoles and pyrrolo[1,2-b]indazoles via Cu(II)-mediated oxidative [3+2]-annulation between nitroalkenes and azolium ylides was developed. The reaction proceeds in mild conditions with copper (II) trifluoroacetate/2,6-lutidine system as a promoter. The method is applicable to a broad range of nitroalkenes and azolium salts, providing target N-fused heterocycles in moderate to good yields. In the case of α-fluoronitroalkenes unique fluorinated derivatives were accessed via this methodology.

Published
2022
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6. Acylation of Nitronates: [3,3]-Sigmatropic Rearrangement of in Situ Generated N-Acyloxy,N-oxyenamines

Author

Aleksandr O. Kokuev, Ivan S. Golovanov, Andrey A. Tabolin, Sema L. Ioffe, Alexey Yu. Sukhorukov, Valentin S. Dorokhov, Yulia A. Antonova, and Yulia V. Nelyubina

Subjects
In situ, 010405 organic chemistry, Stereochemistry, Chemistry, Organic Chemistry, Regioselectivity, Total synthesis, Sigmatropic reaction, 010402 general chemistry, Cleavage (embryo), 01 natural sciences, 0104 chemical sciences, Umpolung, Acylation
Abstract

Acylation of nitronates affords α-acyloxyoxime derivatives via an umpolung functionalization of the α-position. This transformation involves generation of hitherto unknown N-acyloxy, N-oxyenamines and their fast [3,3]-sigmatropic rearrangement driven by the cleavage of the weak N-O bond. The reaction has a broad scope, and it is regioselective in the case of nitronates possessing nonsymmetrically substituted α-positions. Application to the formal total synthesis of clausenamide and cis-clausenamide is presented.

Published
2018
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8. Nucleophilic Halogenation of Cyclic Nitronates: A General Access to 3-Halo-1,2-Oxazines

Author

Roman S. Malykhin, Aleksandr O. Kokuev, Vladimir A. Tartakovsky, Alexey Yu. Sukhorukov, Andrey A. Tabolin, Valentin S. Dorokhov, Sema L. Ioffe, and Yulia V. Nelyubina

Subjects
chemistry.chemical_classification, chemistry, Nucleophile, 010405 organic chemistry, Organic Chemistry, Halogenation, Halide, Oxazines, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences
Abstract

In this article, comprehensive studies on the nucleophilic chlorination and bromination of readily available six-membered cyclic nitronates (1,2-oxazine-N-oxides) are reported. Under optimized conditions (POCl3 or (COBr)2 with Hunig’s base), 3-halo-substituted 1,2-oxazines, which are difficult to access by other routes, were obtained in good to high yields. The latter were shown to be convenient precursors to other 3-substituted 1,2-oxazine derivatives using Lewis/Bronsted acid-assisted substitution of the halide atom for C-, S-, and N-nucleophiles.

Published
2019

10. Radical Nitration-Debromination of α-Bromo-α-fluoroalkenes as a Stereoselective Route to Aromatic α-Fluoronitroalkenes-Functionalized Fluorinated Building Blocks for Organic Synthesis

Author

Roman A. Novikov, Andrey A. Tabolin, Valentine G. Nenajdenko, Sema L. Ioffe, Vasiliy M. Muzalevskiy, Yulia V. Nelyubina, and Vladimir A. Motornov

Subjects
chemistry.chemical_compound, chemistry, 010405 organic chemistry, Nitration, Organic Chemistry, Organic chemistry, Organic synthesis, Stereoselectivity, Sequence (biology), 010402 general chemistry, 01 natural sciences, 0104 chemical sciences
Abstract

A new highly efficient method for the synthesis of 2-fluoro-2-nitrostyrenes was described. Radical nitration of readily available 2-bromo-2-fluorostyrenes with Fe(NO3)3·9H2O resulted in the formation of the corresponding α-fluoro-nitroalkenes in isolated yields up to 92%. The reaction proceeded as a nitration-debromination sequence to highly stereoselectively give α-fluoro-nitroalkenes as Z-isomers only. The broad scope of this method was demonstrated. Prepared monofluorinated alkenes were shown to be versatile building blocks for the synthesis of various fluorinated products.

Published
2017

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