Regio- and stereoselective cycloaddition of nitrones to 1-vinyl-4,5-dihydro-1H-benzo[g]indole

Molchanov, A. P.; Sirotkina, Ekaterina V.; Efremova, Mariia M.; Kostikov, R. R.; Иванов, А. В.; Shcherbakova, V. S.

doi:10.1134/s1070428015050097

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…In this case the regioselectivity was determined by the type of charge control. Preferential formation of cisstereoisomer (the substituents at the C 3 and C 5 atoms) in the reactions of nitrones 5a-5d with N-vinylindole 1 was due to Z-configuration of nitrone and transperiplanar location in the transition state of substituent R 1 and the indolyl group, same as in the reaction with N-vinylpyrrole [19].…”

Section: Methodsmentioning

confidence: 92%

“…Cis-orientation of the substituents at C 3 and C 5 of the isoxozolidine ring of 6a-6d compounds was established by comparing chemical shifts and the constants of spin-spin interaction of the protons of isoxazolidine ring with the data previously obtained for the adducts of the same nitrones with substituted N-vinylpyrroles, namely, the carbamoyl group produced a deshielding effect, and the aromatic ring caused shielding [18,19].…”

Section: Methodsmentioning

confidence: 99%

“…By intramolecular cyclization of carbonyl ylides at the same bond indole alkaloids (aspidophytine, minovin, vindoline) were synthesized [14][15][16][17]. Previously we have studied the reaction of cycloaddition of N-vinylpyrroles with 1,3-dipoles: nitrones [18,19], nitrile oxides, and azomethine imines [20]. All reactions occur regioselectively involving the N-vinyl group and provide an efficient method for the synthesis of compounds containing ensembles of pyrroloisoxazolidine, pyrroloisoxasoline, or pyrazolopyrazolone fragments.…”

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Regio- and stereoselective (3 + 2)-cycloaddition of nitrile oxides and nitrones to N-vinylindole

et al. 2017

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1,3-Dipolar cycloaddition of nitrile oxides and nitrones to N-vinylindole proceeds regioselectively at the exocyclic multiple bond to form 5-indolyl-substituted isoxazolines and isoxazolidines in good yields.An indole fragment is a structural component of a wide range of natural and pharmacologically active compounds. In this context a search for new synthetic routes to compounds containing an indole fragment, particularly in combination with other heterocyclic groups, was considered in a number of reviews [1][2][3][4]. It is known that indole and its derivatives containing an alkyl substituent at the nitrogen atom enter into a reaction of the 1,3-dipolar cycloaddition with nitrile oxides [5-8], nitrile imines [9, 10], and azomethine ylides [11][12][13] at the bond C 2 -C 3 to form heterocyclic compounds containing oxazoline, pyrrole or pyrazoline fragments fused with the indole ring. By intramolecular cyclization of carbonyl ylides at the same bond indole alkaloids (aspidophytine, minovin, vindoline) were synthesized [14][15][16][17]. Previously we have studied the reaction of cycloaddition of N-vinylpyrroles with 1,3-dipoles: nitrones [18,19], nitrile oxides, and azomethine imines [20]. All reactions occur regioselectively involving the N-vinyl group and provide an efficient method for the synthesis of compounds containing ensembles of pyrroloisoxazolidine, pyrroloisoxasoline, or pyrazolopyrazolone fragments.In this work we investigated the regio-and stereoselective interaction of N-vinylindole 1 with 1,3-dipoles: nitrile oxides and nitrones. The reaction of N-vinylindole 1 with nitrile oxides 2a and 2b, which were generated in situ from chloro oximes 3a and 3b at treating with sodium hydrogen carbonate in toluene, leads to the formation of adducts at the N-vinyl group, 5-indolylisoxazolines 4a and 4b. The yield was 67 and 72%, respectively (Scheme 1). NMR spectra showed that no regioisomeric addition products were present in the reaction mixtures. The structure of the compounds was established proceeding from the spectral data. For example, in the 1 H NMR spectrum of compound 4a along with the aromatic proton signals there were three signals of the isoxazoline ring protons at 3.61 d.d (J 17.8, 4.3 Hz), 3.81 d.d (J 17.8, 9.9 Hz), and of the methine proton in the position 5 at 6.86 d.d (J 9.9, 4.3 Hz). In the 13 C NMR spectrum the corresponding signals of carbon atoms of isoxasoline cycle were located at 40.1 (CH 2 ), 86.3 (CH), and 155.4 (C= N) ppm. Scheme 1. 3a, 3b 4a, 4b 2a, 2b N Cl R OH R N O NaHCO 3 _ + N 1 O N N R R = 4-ClC 6 H 4 (a), COOEt (b).

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Section: Methodsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Regio- and stereoselective (3 + 2)-cycloaddition of nitrile oxides and nitrones to N-vinylindole

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“…For instance, in 2015, Efremova and coworkers [7] reported that the reaction of nitrile oxides and N-vinylpyrrole proceeds by normal 1,3-dipolar cycloaddition with high regioselectivity to give only 5-(1H-pyrrol-1-yl) isoxazoles. Moreover, Efremova et al [8] in 2016 studied the regioand stereoselective (3 + 2)-cycloaddition of nitrile oxides (A3) and nitrones (A2) to N-Vinylindole (A1) as shown in Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation of the regio-, enantio-, and stereo-selectivities of the (3 + 2) cycloaddition reactions of N-vinylindoles with nitrones and nitrile oxides

et al. 2021

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The 1,3-dipolar cycloadditions of nitrones and nitrile oxides to N-vinylindole afford isoxazolidines and 5-indolyl-substituted isoxazolines which are structural components of a wide range of natural and pharmaceutically active compounds. In these reactions, there are several regio-, enantio-, and stereo-chemical possibilities, leading to several potential pathways, and these pathways are studied with density functional theory calculations at the M06/6-311G(d,p) level of theory. The results show that the electron-withdrawing substituents on the dipolarophile accelerate the (3 + 2) cycloaddition reactions of nitrones with N-vinylindole by lowering the activation barriers of the reaction. The (3 + 2) cycloaddition of electron-withdrawing and electron-donating substituted nitrones with N-vinylindole proceeds with the preferential formation of cis-stereoisomers, and this is due to the Z-configuration of the nitrone and the trans-periplanar orientation of the substituents and the indolyl group on the transition state. The reactions of nitrile oxides with N-vinylindole proceed regioselectively at the exocyclic double bond in the indole to form 5-indolyl-substituted-isoxazolines. It has been established that the (3 + 2) cycloaddition of electron-donating and electron-withdrawing substituted nitrones and nitrile oxides to N-vinylindole is not enantioselective. The global electrophilicity indices (ω) and maximum electronic charge transfer (ΔN max ) computed for various nitrones and nitrile oxides considered in this work are consistent with energetic trends and experimental outcomes. The analysis of the electrophilic (P k + ) and nucleophilic (P k −) Parr functions at the reactive centers shows that the cycloaddition will happen in such a way as to unite the atoms with the highest molecular orbital coefficients because this would lead to the greatest stabilization, and this is in good agreement with the energetic trends and the experimental outcome.

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Cycloaddition of nitrones to 1,3-diarylpropenones and subsequent transformations of the resulting isoxazolidines

Sirotkina

Efremova

Старова

et al. 2020

Chem Heterocycl Comp

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Regio- and stereoselective cycloaddition of nitrones to 1-vinyl-4,5-dihydro-1H-benzo[g]indole

Cited by 9 publications

References 5 publications

Regio- and stereoselective (3 + 2)-cycloaddition of nitrile oxides and nitrones to N-vinylindole

Regio- and stereoselective (3 + 2)-cycloaddition of nitrile oxides and nitrones to N-vinylindole

Theoretical investigation of the regio-, enantio-, and stereo-selectivities of the (3 + 2) cycloaddition reactions of N-vinylindoles with nitrones and nitrile oxides

Cycloaddition of nitrones to 1,3-diarylpropenones and subsequent transformations of the resulting isoxazolidines

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