Research on 1-aza two-ring systems

Skvortsov, I. M.; Antipova, I. V.

doi:10.1007/bf00471198

Cited by 5 publications

(13 citation statements)

References 8 publications

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“…Comparison of the physical characteristics of the epimers 11 and 18 [33] shows that they do not conform to the conformational rule in all the main physical characteristics; the first has lower boiling point, density, and refractive index than the second. The analogous characteristics of the base 11 agree with the idea that transfusion is preferred for this compound in the liquid phase.…”

Section: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 92%

“…With increase in temperature the signal of the bridgehead C (8) atom is shifted downfield to the region where the signals of the C (8) atoms of the highly strained predominantly trans-fused compounds 10 (70.1 or 71.0 ppm) and 11 (72.7 ppm) lie [14,19].…”

Section: Detection Of Conformational Heterogeneity In Pyrrolizidines mentioning

confidence: 99%

“…The analogous characteristics of the base 11 agree with the idea that transfusion is preferred for this compound in the liquid phase. Its molecule in conformation A occupies a larger volume and has a smaller dipole moment [33] than in the cis-fused form B. In geometric respects the investigated pair of isomers is similar in the form of the bicycle to the pair of their carbocyclic analogs 2 and 3, for which the conformational rule is not obeyed [13].…”

Section: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 99%

“…However, there are strong angular strains in forms A [2,14,15,17]. In spite of this many pyrrolizidine derivatives of types 6 and 7 exist preferentially in the trans-fused conformations A [14,[17][18][19][20][21][22][23], demonstrating the considerable supremacy of the cis-fused forms B with respect to strain that determines the preference for the A forms.…”

mentioning

confidence: 99%

“…The pyrrolizidines were subdivided provisionally into unstrained and weakly and highly strained bases, according on the strength of the nonbonding interactions in the cis-fused forms B [14,15]. It should be understood that we are not discussing compounds in which the strain originates from interaction between sterically close substituents at the C (1) and C (7) atoms.…”

mentioning

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: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 92%

Section: Detection Of Conformational Heterogeneity In Pyrrolizidines mentioning

confidence: 99%

Section: Physical Constants and Gas-liquid Chromatographymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

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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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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Coupled Organolanthanide-Catalyzed C−N/C−C Bond Formation Processes. Efficient Regiospecific Assembly of Pyrrolizidine and Indolizidine Skeletons in a Single Catalytic Reaction

Marks

1996

J. Am. Chem. Soc.

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Research on 1-aza two-ring systems

Cited by 5 publications

References 8 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

Coupled Organolanthanide-Catalyzed C−N/C−C Bond Formation Processes. Efficient Regiospecific Assembly of Pyrrolizidine and Indolizidine Skeletons in a Single Catalytic Reaction

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