Configurational analysis of tetracyclic dimeric pyrrole-imidazole alkaloids using a floating chirality approach

J Nat Prod. 2012 Feb 24;75(2):127-30. doi: 10.1021/np200514g. Epub 2012 Feb 14.

Abstract

The structure elucidation of the palau'amine congener tetrabromostyloguanidine (1), which used interproton distances from ROESY spectra as restraints in a computational approach, the so-called fc-rDG/DDD method, led to a revision of the relative configuration of palau'amine (2) and its congeners in 2007. The recent total synthesis of (±)-palau'amine (2) subsequently confirmed the computed structural revision of the relative configuration. In order to test a broader application range of the fc-rDG/DDD method, the present study investigated two additional dimeric pyrrole-imidazole alkaloids, axinellamine A (3) and 3,7-epi-massadine chloride (4). These calculations allowed the simultaneous assignment of the relative configuration for all eight stereogenic centers of compounds 3 and 4 without using any information from the reported configurations. In contrast to the palau'amine congeners, the fc-rDG/DDD method confirmed the relative configuration originally described for axinellamine A (3) and 3,7-epi-massadine chloride (4).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkaloids / chemical synthesis*
  • Alkaloids / chemistry*
  • Guanidines / chemical synthesis*
  • Guanidines / chemistry*
  • Imidazoles / chemical synthesis*
  • Imidazoles / chemistry
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Pyrroles / chemical synthesis*
  • Pyrroles / chemistry
  • Spiro Compounds / chemical synthesis*
  • Spiro Compounds / chemistry*
  • Stereoisomerism

Substances

  • Alkaloids
  • Guanidines
  • Imidazoles
  • Pyrroles
  • Spiro Compounds
  • axinellamine
  • palau'amine