Dimeric tropane alkaloids

Literature information on dimeric alkaloids of the tropane series is generalized.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 447–455, July–August, 1991.     

Dimeric tropane alkaloids

Literature information on dimeric alkaloids of the tropane series is generalized.     

Dimeric indoline alkaloids of a new biphenyl type

A ¹³C NMR analysis of lochnericine and the new alkaloids peceyline, peceylanine and pelankine is presented and the structures of the indoline dimers described.     

Haplodimerine — A new type of dimeric quinoline alkaloids

A base, which has been called haplodimerine, has been isolated from the fruit of the plantHaplophyllum foliosum Vved. It has been established by x-ray structural analysis that haplodimerine includes fragments of the known alkaloids skimmianine and flindersine attached to one another through the double bonds of furan and dimethylpyran rings with the formation of a four-membered ring.     

Electron impact mass spectrometry of hemiterpenoid tricyclic quinoline alkaloids

The mass spectral behaviour of some quinoline-type alkaloids, 3,4-dihydro-2H,5H-pyrano[3,2-c]quinolin-5-ones, isomeric 3,4-dihydro-2H,5H-pyrano[2,3-b]quinolin-5-ones and 2H,5H-pyrano[3,2-c]quinolin-5-ones, was studied in detail with the aid of linked scans, exact mass measurements and collisional spectrometry. The occurrence of a partial isomerization of the differently annulated isomers to a common, open-chain structure is discussed.     

seco-limonoids and quinoline alkaloids from Raputia heptaphylla and their antileishmanial activity

A novel seco-limonoid, rel-(1S,5R,9S,7R,8S,9R,10S,11R,13S,14R,15R,17R)-11,19-dihydroxy-7-acetoxy-7-deoxoichangin (raputiolide) (1), and two novel quinolone alkaloids N-methyl-2-phenoxyquinolin-4(1H)-one (heptaphyllone A) (2) and 6-methylbenzofuro[2,3-b]quinolin-4(1H)-one (heptaphyllone B) (3), along with the known seco-limonoid ichangin (4), were isolated from Raputia heptaphylla PITTIER (Rutaceae) stem bark. Five known alkaloids, N-methyl-8-methoxyflindersine (5), skimmianine (6), kokusaginine (7), dictamnine (8) and flindersiamine (9), were also isolated from R. heptaphylla leaves. Their structures were established on the basis of full spectroscopic data interpretation supported by data from the pertinent literature. seco-Limonoid 1 configuration was determined by enhanced nuclear Overhauser effect spectroscopy (NOESY) experiments and density functional theory (DFT) molecular modeling. The antileishmanial effect of the isolated compounds was evaluated on Leishmania Viannia panamensis (promastigotes and amastigotes). Whereas alkaloids 2-3, 6-8 and limonoid 4 exhibited no significant parasitocide activity against internalized L. (V.) panamensis amastigotes, limonoid 1 and alkaloid 5 had leishmanicidal activity on intracellular amastigotes (EC??: 8.7 μg/ml) and promastigotes (EC(50): 14.3 μg/ml), respectively.     

Synthesis, structure and stereochemistry of quinoline alkaloids from Choisya ternata

A range of seventeen quinoline alkaloids, involving several types of oxidations during their biosynthetic pathways, have been isolated from leaves of Choisya ternata. In addition to the nine known quinoline alkaloids, eight new members of the furoquinoline family, derived mainly from prenylation at C-5 (including two novel hydroperoxides), have been identified. The absolute configurations and enantiopurity values of all chiral quinoline alkaloids have been determined. One of the isolated alkaloids, 7-isopentenyloxy-gamma-fagarine, has been used as a precursor for the chemical asymmetric synthesis of the enantiopure alkaloids: evoxine, anhydroevoxine and evodine. The possible roles of oxygenase and other oxygen-atom-transfer enzymes, in the biosynthetic pathways of the C. ternata alkaloids, have been discussed.     

Dimeric indole alkaloids of a new type a synthetic approach to the ervafoline series

A synthetic approach towards the dimeric ervafoline indole alkaloids has been achieved $\text{via}$ a route inspired from a biogenetic hypothesis.     

Structure elucidation and NMR assignments of two new pyrrolidinyl quinoline alkaloids from chestnut honey

The complete ¹H, ¹³C and ¹⁵N NMR spectral assignments of two new alkaloids isolated from chestnut honey and structurally related to kynurenic acid have been made using 1‐D and 2‐D NMR techniques, including COSY, HMQC and HMBC experiments. The new compounds have been identified as 3‐(2′‐pyrrolidinyl)‐kynurenic acid and its γ‐lactam derivative. Copyright © 2009 John Wiley & Sons, Ltd.     

Quinoline alkaloids—XXI: The C nmr spectra of hemiterpenoid quinoline alkaloids and related prenylquinolines

¹³C NMR spectra of twenty-five hemiterpenoid quinoline alkaloids and related prenylquinolines were determined; C-, O- and N-prenyl-quinolines and -quinolone derivatives, hydroxyisopropyldihydrofuroquinolones, hydroxydimethyldihydropyranoquinolones and furoquinolines are included. Chemical shifts were assigned by proton single-frequency and off-resonance decoupling and by comparison with model compounds.     

Megistoquinones I and II, two quinoline alkaloids with antibacterial activity from the bark of Sarcomelicope megistophylla

Two alkaloids, megistoquinone I (1) and megistoquinone II (2), were isolated from the bark of Sarcomelicope megistophylla. Their structures have been elucidated on the basis of MS and NMR data. Both belong to quinoline alkaloid series and should be considered as oxidation products of a furo[2,3-b]quinoline precursor. The two alkaloids showed antibacterial properties with minimum inhibitory concentration (MIC) ranging from 2.35 to 5.25 mg/ml for 1 and 0.73 to 1.23 mg/ml for 2.     

Efficient construction of cyclopenta[b]quinoline core of isoschizozygane alkaloids via intramolecular formal hetero-Diels-Alder reaction

[reaction: see text] Acid-catalyzed condensation of aromatic amines with delta,epsilon-unsaturated aldehydes, followed by intramolecular formal hetero Diels-Alder reaction, is described as a potential route to the cyclopenta[b]quinoline substructure of isoschizozygane alkaloids. Reactions are highly diastereoselective and produce adducts with up to four contiguous stereocenters.     

海洋二聚吡咯-咪唑类生物碱

近20年来,大量二聚吡咯-咪唑类生物碱从海绵中分离得到,并表现出良好的生理活性。而这些分离上的进展,为确定该类化合物结构提供新的信息,更促进了生源合成的研究发展。这类化合物因其结构新颖性、多样性以及良好的生理活性而成为合成化学家们关注的焦点。由于该类天然产物分子结构的复杂性、分子中的高氮数(N/C ≈ 1 ∶2)以及不确定的绝对构型,使得这类分子的合成十分具有挑战性。本文主要综述了海洋二聚吡咯-咪唑类生物碱的分离和合成进展。     

Dimeric proanthocyanidins ofCotoneaster oligantha

Summary 1. Five flavans have been isolated from the stems ofCotoneaster oligantha A. Pojark, and have been identified; two of them are (+)-catechin and (–)-epicatechin and three are stereoisomeric dimeric procyanidins.2. The proanthocyanidins have the structure of dimers of 3,4,5,7-tetrahydroxyflavan-3-ol with C₄-C₈ (or C₆) bonds between the flavan moieties and with the cis (2R:3R) configuration of the asymmetric centers (flavans 3 and 5) and trans (2R:3S:4S) configuration of the upper half and the cis configuration of the lower half of the molecule (flavan 4).S. M. Kirov Kazakh State University, Alma-Ata. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 204–212, March–April, 1978.     

Dimeric proanthocyanidins ofHibiscus cannabinus

Two dimeric proanthocyanidins have been isolated from the bark and roots of kenaf of variety Uzbekskii 1574. On the basis of chemical transformations and NMR and mass-spectral analyses it has been established that the proanthocyanidins have the structure of a dehydro dimer of 3,3′,4′,5,7-pentahydroxyflavan and that of 8-(3-galloyloxy-3′,4′,5,7-tetrahydroxyflavan-4-yl)-3,3′,4′,5,7-pentahydroxyflavan, respectively, with a C₄-C₈ (or C₆) bond between the flavan moieties.