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Ancistrocladinium A and B, the first N,C-coupled naphthyldihydroisoquinoline alkaloids, from a Congolese Ancistrocladus species

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  • Gerhard Bringmann
  • Inga Kajahn
  • Matthias Reichert
  • Sarah E.H. Pedersen
  • Johan H. Faber
  • Tanja Gulder
  • Reto Brun
  • Christensen, Søren Brøgger
  • Alicia Ponte-Sucre
  • Heidrun Moll
  • Günther Heubl
  • Virima Mudogo

(Chemical Equation Presented) The isolation and structural elucidation of three novel-type naphthylisoquinoline alkaloids, ancistrocladinium A and B (the latter along with its atropisomer), from a Congolese Ancistrocladus species collected in the habitat Yeteto is reported. Their structures, including all stereochemical features, were elucidated by spectroscopic, chemical, and chiroptical methods. Ancistrocladinium A and B are the first N,C-coupled naphthyldihydroisoquinoline alkaloids found in nature, i.e., with an iminium-aryl axis. Although ancistrocladinium A, which is N,8′-coupled, is configurationally stable at this axis, ancistrocladinum B and its rotational isomer are based on a hitherto unprecedented N,6′-coupling type, with a slow rotation about the hetero biaryl axis at room temperature; they thus occur as a 46:54 mixture of two configurationally semistable atropo-diastereomers. For the isomerization of (P)-ancistrocladinium B to its (M)-diastereomer and for the opposite direction, the Gibbs free energies of activation were determined to be ΔG1 = 105.8 kJ mol-1 and ΔG2 = 105.7 kJ mol-1, respectively. In addition, the compounds were shown to have promising antileishmanial activities.

OriginalsprogEngelsk
TidsskriftJournal of Organic Chemistry
Vol/bind71
Udgave nummer25
Sider (fra-til)9348-9356
Antal sider9
ISSN0022-3263
DOI
StatusUdgivet - 8 dec. 2006

ID: 232592889