Antineoplastic Agents. 36. Crystal and Molecular Structure of the Pseudoguaianolide Autumnolide

Robert B. Von Dreele, George Pettit, Gordon M. Cragg, Richard H. Ode

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16 Scopus citations


A crystal structure analysis of the pseudoguaianolide autumnolide (3) has revealed a conformation of the sevenmem bered ring that is markedly different from that found for the very similar bromohelenalin. The principal difference between the two conformations involves a drastic twist of 111.0° about C6-C7 and associated rotations about all contiguous bonds. As a consequence of this molecular conformation, there is an unusual OH-pπ interaction in autumnolide which is not found in the other pseudoguaianolides. The structure was solved by direct methods analysis of data from a crystal with space group P21 and a = 7.595 ± 0.004, b = 13.380 ± 0.009, c = 6.870 ± 0.006 Å, β = 92.87 ± 0.06°, Z = 2, and density ρcaicd = 1.336 g/cm3. An anisotropic full-matrix least-squares refinement converged to a conventional residual of R = 0.058 for 2086 reflections recorded with Mo Ka radiation on an automatic four-circle diffractometer.

Original languageEnglish (US)
Pages (from-to)5256-5259
Number of pages4
JournalJournal of the American Chemical Society
Issue number18
StatePublished - Sep 1 1975

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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