Research on 1-aza two-ring systems

Skvortsov, I. M.; Astakhova, L. N.; Evtushenko, I. Ya.; Cheslavskaya, E. V.; Kuz'min, S. N.; Voronin, S. P.

doi:10.1007/bf00475392

Cited by 3 publications

(9 citation statements)

References 17 publications

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“…An analogous substantial difference is observed for the position of the resonance signal of the C (8) atom in the 13 C NMR spectra of highly strained and unstrained or weakly strained pyrrolizidines; in the spectra of the former this signal lies in a significantly more downfield region (70.1-72.7 ppm) than in the spectra of the other bases [17,19,20,22,23,32]. We note that the position is as a rule unusually low in comparison with the position of the signals for the bridgehead carbon atoms in the spectra of quinolizidine and indolizidine (62.9-64.1 ppm), which also have trans-fusion of the rings [41][42][43].…”

Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 63%

“…Comparison of the physical characteristics in the pairs of isomers 11 and 19, 26 and 32, and 27 and 33 shows that, as in the cases examined above, the predominantly trans-fused bases also have lower boiling points, densities, and refractive indices than their isomers with predominantly cis-fused rings [30,32,33].…”

Section: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 88%

“…In aqueous solution the unstrained and weakly strained pyrrolizidines 1, 8, 9, 18, 19, and 22 have comparatively high basicity (pK a 10.88-11.94) [32,34,[44][45][46] and are apparently the strongest bases among saturated amines with tertiary nitrogen atoms [17,46]. This feature is due to the geometry of the cis-fused pyrrolizidines, which have the unshared electron pair of the nitrogen atom sterically accessible for hydration [7,17,45,46].…”

Section: Basicitymentioning

confidence: 99%

“…In [17,20,22,23,32,[37][38][39] it was shown that Boltzmann absorption also appears in the case of strained trans-fusion of two saturated five-membered rings with a bridgehead nitrogen atom. The region of application of the correlation has thus been extended.…”

Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 99%

“…Thus, in the IR spectra of the highly strained pyrrolizidines 10 and 11 [37][38][39], 26 [17], 27 [32], 36 [20,22], and 46 [23] in the region of 2650-2800 cm -1 there are 3-5 so-called Boltzmann bands of weak and medium intensity typical of trans-fused azabicycles with a bridgehead nitrogen atom [35].…”

Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 99%

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Cis-trans-conversion of the bicycle in pyrrolizidines: The effect of the preferred conformations on the properties of the bases and the thermodynamics of conformational transformation of the ring fusion type. (Review)

Skvortsov

2006

Chem Heterocycl Compd

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The cis-trans conversion in pyrrolizidines and the deciding effect of steric factors on their conformational equilibrium are discussed. Work on the synthesis and characteristics of sterically strained pyrrolizidines is analyzed and discussed. It is shown that such compounds (predominantly trans-fused) have a series of features in their properties that greatly distinguish them from unstrained pyrrolizidines. The first results from study of the thermodynamics of cis-trans conversion of the pyrrolizidine bicycle are summarized.

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Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 63%

Section: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 88%

Section: Basicitymentioning

confidence: 99%

Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 99%

Section: Infrared and 1 H And 13 C Nmr Spectramentioning

confidence: 99%

See 3 more Smart Citations

Cis-trans-conversion of the bicycle in pyrrolizidines: The effect of the preferred conformations on the properties of the bases and the thermodynamics of conformational transformation of the ring fusion type. (Review)

Skvortsov

2006

Chem Heterocycl Compd

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Investigations on 1-azabicycles. 26*. IR spectra of the simplest pyrrolizidine alcohols in the region of the stretching vibrations of the hydroxyl group and their connection with the stereochemistry of the compounds

Tarasov

Kolesnikov

Levin

et al. 2009

Chem Heterocycl Comp

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The IR spectra in the hydroxyl group stretching vibration region of the simplest hydroxyalkylpyrrolizidines have been examined. The spectra were taken in the form of pure liquids, dilute solutions in carbon tetrachloride, and for individual bases in the gas phase. It was shown that in dilute solutions ∆ν OH depends on the geometric parameters of the intramolecular hydrogen bond (IMHB) . The energy of the IMHB of 3-(2-hydroxyethyl)pyrrolizidine was measured in dilute solution and in the gas phase.A large number of studies has been devoted to the synthesis and structure of pyrrolizidine alcohols, especially those forming the basis of pyrrolizidine alkaloids. In spite of this, problems linked with hydrogen bonds in pyrrolizidine alcohols have obtained only limited exposure. The investigation of aminodiols, the alkaloids platinecine and retronecine, in which the hydroxyl groups are connected with hydrogen bonds, are part of the previous work in this region [2].Meanwhile, regularities of the link of the structure of compounds with the character of the absorption in the region of stretching vibrations of the OH group, found for the simplest pyrrolizidine alcohols, are of interest not only in themselves but may also prove to be useful when investigating more complex compounds of this series.

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Studies Towards Diastereoselective Additions of 2,2-Dimethyl-3,4-dihydro-2H-pyrrole N-Oxide to Chiral Acrylates and Crotonates

Nadkarni¹,

Baskaran²,

Sawant³

et al. 1998

J. Chem. Res.

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Research on 1-aza two-ring systems

Cited by 3 publications

References 17 publications

Cis-trans-conversion of the bicycle in pyrrolizidines: The effect of the preferred conformations on the properties of the bases and the thermodynamics of conformational transformation of the ring fusion type. (Review)

Cis-trans-conversion of the bicycle in pyrrolizidines: The effect of the preferred conformations on the properties of the bases and the thermodynamics of conformational transformation of the ring fusion type. (Review)

Investigations on 1-azabicycles. 26*. IR spectra of the simplest pyrrolizidine alcohols in the region of the stretching vibrations of the hydroxyl group and their connection with the stereochemistry of the compounds

Studies Towards Diastereoselective Additions of 2,2-Dimethyl-3,4-dihydro-2H-pyrrole N-Oxide to Chiral Acrylates and Crotonates

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