Molecular and crystal structure of tetrahydroneosophoramine

Ибрагимов, Б. Т.; Talipov, S. A.; Tishchenko, G. N.; Kushmuradov, Yu. K.; Aripov, T. F.; Kuchkarov, S.

doi:10.1007/bf00574374

Cited by 10 publications

(6 citation statements)

References 1 publication

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“…44 Conversely, the cis-or cisoid isomer has indications of a larger conformational strain, showing a small N pyramidalization (sum of internal angles of 357.0º) and deviation of the lactamic fragment C14-C15-N16-C11 from linearity (τ = -16.5º), which results in a 12 H13 half-chair isomer (C12 and C13 on opposite sides of the average plane), with puckering coordinates (θ=37.2, φ=217.2) close to the positive (q3>0) envelope/half-chair pseudorotation pathway (θ=50.8°-54.7°). The gas-phase structural data are qualitatively similar to the solid phase (i.e., differences in torsion angles of 1-5º in Figure S3, SI) 23,24 and confirm that the origin of matrine isomerism is intrinsic to the molecule and cannot be attributed to crystal packing effects or intermolecular forces. Because of the relatively small potential barriers, neither the lactamic conformational rearrangements nor the plausible amine inversion isomerism 45 of matrine produce rigid stereocenters and cannot be referred as diastereoisomers.…”

Section: Resultssupporting

confidence: 58%

“…20,21 However, some specific issues and the absolute configuration of several derivatives are still debatable. Concerning matrine stereochemistry, reviews by Ibragimov et al 22 based on the independent crystal diffraction observation of two different species denoted (C/D) trans-matrine 23 and cis-matrine 24 suggested that the two nitrogen atoms (N1 and N16)…”

Section: Introductionmentioning

confidence: 99%

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Molecular Rotation Spectrum of Tetracyclic Quinolizidines: Observation of trans-Matrine and the Elusive cis-Matrine

et al. 2021

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We characterized the bis-quinolizidine tetracyclic alkaloid (5S, 6S, 7R, 11R)-matrine in a supersonic jet expansion, using chirped-pulsed broadband microwave spectroscopy. Previous crystal diffraction analyses suggested 16 diastereoisomers associated with matrine’s four carbon stereocenters but were inconclusive whether the lactamic nitrogen atom would additionally produce separated trans-/cis- diastereoisomers or if both species may interconvert through low potential barriers. Our experiment simultaneously detected trans- and cis-matrine through their rotational spectrum, confirming the possibility of conformational rearrangement in matrine alkaloids. The two matrine conformers mainly differ in the envelope or half-chair lactamic ring, as evidenced by the experimental rotational and nuclear quadrupole coupling parameters. Molecular orbital calculations with ab initio (MP2) and density functional methods (B3LYP-D3(BJ) and MN15) were tested against the experiment, additionally offering an estimation of the cis-/trans- barrier of 24.9–26.9 kJ mol–1. The experiment illustrates the structural potential of chirped-pulsed broadband microwave spectroscopy for high-resolution rotational studies of biomolecules in the range of 20–40 atoms.

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Section: Resultssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Molecular Rotation Spectrum of Tetracyclic Quinolizidines: Observation of trans-Matrine and the Elusive cis-Matrine

et al. 2021

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“…16 This arrangement theoretically results in 64 stereoisomers or 32 enantiomeric pairs for the matrine-type alkaloids, as originally proposed by Ibragimov and co-workers. 28 Thus far, nine stereoisomers in the matrine family have been reported (assignments of the C stereogenic centers are given in parentheses): trans-matrine (SSSR), 15,16 cis-matrine (RRRS), 29 allomatrine (SRSR), 30 sophoriridine (SRRS), 18 isomatrine (RRRR), 31 isosophoridine (SSRS), 32 tetrahydroneosophoramine (SRRR), 33 trans-neomatrine (SSRR), and cis-neomatrine (SSRR). 34 Some confusion exists about the chirality labeling of the matrine compounds, especially at C-7.…”

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confidence: 99%

IR and Vibrational Circular Dichroism Spectroscopy of Matrine- and Artemisinin-Type Herbal Products: Stereochemical Characterization and Solvent Effects

et al. 2016

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Five Chinese herbal medicines--matrine, oxymatrine, sophoridine, artemisinin, and dihydroartemisinin--were investigated using vibrational circular dichroism (VCD) experiments and density functional theory calculations to extract their stereochemical information. The three matrine-type alkaloids are available from the dry roots of Sophora flavescens and have long been used in various traditional Chinese herbal medicines to combat diseases such as cancer and cardiac arrhythmia. Artemisinin and the related dihydroartemisinin, discovered in 1979 by Professor Youyou Tu, a 2015 Nobel laureate in medicine, are effective drugs for the treatment of malaria. The VCD measurements were carried out in CDCl3 and DMSO-d6, two solvents with different dielectric constants and hydrogen-bonding characteristics. A "clusters-in-a-liquid" approach was used to model both explicit and implicit solvent effects. The studies show that effectively accounting for solvent effects is critical to using IR and VCD spectroscopy to provide unique spectroscopic features to differentiate the potential stereoisomers of these Chinese herbal medicines.

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“…A majority of the known biologically active constituents belong to the matrine family of alkaloids ( 4 , Figure A). , These tetracyclic natural products comprise an AB quinolizidine bicycle linked to a D ring piperidone through fusion of a C ring piperidine. Six natural diastereomeric forms are known, − of which ( cis , cis , anti )-matrine ( 2 ) is the most abundant, with ( trans , trans , anti )-allomatrine ( 3 ) and ( cis , cis , syn )-isomatrine ( 1 ) being 16 and 286 times less abundant, respectively . Matrine ( 2 ) has anticancer activity through proliferation inhibition and apoptosis induction of various cancer cell lines .…”

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confidence: 99%

Total Synthesis of Matrine Alkaloids

et al. 2022

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The total synthesis of three diastereomeric matrine natural products is reported. The 8-step synthesis commences with simple acyclic precursors, forms all 4 rings of the tetracyclic natural product framework, and forges 10 of the 20 covalent bonds of the target structure. A cross-conjugated triene is positioned at the core of an acyclic branched structure. This precursor collapses to the tetracyclic natural product framework through an orchestrated sequence of two separate intramolecular cycloadditions. A subsequent, late-stage hydrogenation is accompanied by strain-release redox epimerizations to deliver the three natural products. An unprecedented carba-analogue is prepared in the same way. Semisynthetic manipulations of matrine provide access to 10 additional natural products.

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Molecular and crystal structure of tetrahydroneosophoramine

Cited by 10 publications

References 1 publication

Molecular Rotation Spectrum of Tetracyclic Quinolizidines: Observation of trans-Matrine and the Elusive cis-Matrine

Molecular Rotation Spectrum of Tetracyclic Quinolizidines: Observation of trans-Matrine and the Elusive cis-Matrine

IR and Vibrational Circular Dichroism Spectroscopy of Matrine- and Artemisinin-Type Herbal Products: Stereochemical Characterization and Solvent Effects

Total Synthesis of Matrine Alkaloids

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