Effect of substituents and structural modification on conformational equilibrium in bis-quinolizidine system

Wysocka, Waleria; Brukwicki, Tadeusz; Włodarczak, Jacek

doi:10.1016/j.molstruc.2012.03.006

Cited by 3 publications

(2 citation statements)

References 88 publications

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“…All characterization data (IR, 1 H and 13 C NMR, optical rotation, and melting point) of synthetic baptifoline ( A ) and epibaptifoline ( B ) excellently matched the data published for the natural products, and, thus, prove their identity. The central bispidine core of both alkaloids A and B adopts the expected chair‐chair conformation, as evident from the small coupling constants ( J ≤ 2.6 Hz) between 17‐H exo and the bridgehead proton 7‐H (synclinal arrangement) …”

Section: Resultsmentioning

confidence: 97%

The Hydroxylated, Tetracyclic Bisquinolizidine Alkaloids Baptifoline and Epibaptifoline: Enantioselective Synthesis and Unambiguous Assignment of their Configuration at C‐13

2018

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The epimeric bisquinolizidines baptifoline and epibaptifoline are C‐13 hydroxylated derivatives of the well‐known lupine alkaloid anagyrine. We synthesized both compounds from 11‐allylcytisine and determined their uncertain configuration at the C‐13 stereocenter by NMR, chemical transformation, and X‐ray. The alcohol function was found to be in endo (α) position in baptifoline (configuration: 7R, 9R, 11R, 13R) and in exo (β) position in epibaptifoline (configuration: 7R, 9R, 11R, 13S).

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Section: Resultsmentioning

confidence: 97%

The Hydroxylated, Tetracyclic Bisquinolizidine Alkaloids Baptifoline and Epibaptifoline: Enantioselective Synthesis and Unambiguous Assignment of their Configuration at C‐13

2018

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“…Recent research on the hypoglycemic impact of certain quinolizidine alkaloids indicates that compounds with more labile structures may exhibit higher effectiveness. Additionally, the taste intensity of bis-quinolizidine compounds appears to be related to their conformational equilibrium state [24].…”

Section: Introductionmentioning

confidence: 99%

Quantitation of Lupinus spp. Quinolizidine Alkaloids by qNMR and Accelerated Debittering with a Resin-Based Protocol

Madelou,

Melliou,

Magiatis

2024

Molecules

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Quinolizidine alkaloids (QAs) are toxic secondary metabolites of the Lupinus species, the presence of which limits the expansion of lupin beans consumption, despite their high protein content. Evaluation of the level of alkaloids in edible Lupinus species is crucial from a food safety point of view. However, quantitation of QAs is complicated by the fact that not all important alkaloids used for quantitation are commercially available. In this context, we developed a method for the simultaneous quantitation of eight major lupin alkaloids using quantitative NMR spectroscopy (qNMR). Quantitation and analysis were performed in 15 different seed extracts of 11 Lupinus spp. some of which belonged to the same species, with different geographical origins and time of harvest, as well as in all aerial parts of L. pilosus. The mature seeds of L. pilosus were found to be a uniquely rich source of multiflorine. Additionally, we developed a protocol using adsorption or ionic resins for easy, fast, and efficient debittering of the lupine seeds. The protocol was applied to L. albus, leading to a decrease of the time required for alkaloids removal as well as water consumption and to a method for QA isolation from the debittering wastewater.

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Protonation-triggered conformational modulation of an N,N′-dialkylbispidine: first observation of the elusive boat–boat conformer

et al. 2013

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Modulation of the solution conformations of N,N'-bis(benzhydryl)bispidine has been achieved by protonation. Conformers have been characterized by NMR spectroscopy using nuclear Overhauser effects and residual dipolar couplings. In contrast to the preference for the chair-chair conformation for the free base and the monoprotonated species, the diprotonated bispidine is revealed to exist as a mixture of chair-boat and boat-boat conformers. While boat-boat conformers of bispidines have previously not been detected, they are here observed to constitute up to 70% of the bispidine population.

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Effect of substituents and structural modification on conformational equilibrium in bis-quinolizidine system

Cited by 3 publications

References 88 publications

The Hydroxylated, Tetracyclic Bisquinolizidine Alkaloids Baptifoline and Epibaptifoline: Enantioselective Synthesis and Unambiguous Assignment of their Configuration at C‐13

The Hydroxylated, Tetracyclic Bisquinolizidine Alkaloids Baptifoline and Epibaptifoline: Enantioselective Synthesis and Unambiguous Assignment of their Configuration at C‐13

Quantitation of Lupinus spp. Quinolizidine Alkaloids by qNMR and Accelerated Debittering with a Resin-Based Protocol

Protonation-triggered conformational modulation of an N,N′-dialkylbispidine: first observation of the elusive boat–boat conformer

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