Conformational analysis of (+)-germacrene A by variable-temperature NMR and NOE spectroscopy

Juan A. Faraldos, Shuiqin Wu, Joe Chappell, Robert M. Coates

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

(+)-Germacrene A, an important intermediate in sesquiterpene biosynthesis, was isolated in pure form from a genetically engineered yeast and was characterized by chromatographic properties (TLC, GC), MS, optical rotation, UV, IR, 1H NMR, and 13C NMR data. Variable-temperature 500 MHz 1H NMR spectra in CDCl3 showed that this flexible cyclodecadiene ring exists as three NMR-distinguishable conformational isomers in a ratio of about 5:3:2 at or below ordinary probe temperature (25 °C). The conformer structures were assigned by 1H NMR data comparisons, NOE experiments, and vicinal couplings as follows: 1a (52%, UU), 1b (29% UD), and 1c (19%, DU).

Original languageEnglish
Pages (from-to)7733-7742
Number of pages10
JournalTetrahedron
Volume63
Issue number32
DOIs
StatePublished - Aug 6 2007

Bibliographical note

Funding Information:
We are very grateful to Dr. A. M. Adio for exchanges of information and for 1D and 2D NMR spectra of an impure sample of germacrene A isolated from S. Canadensis, 26 Dr. Vera Mainz of the School of Chemical Sciences NMR Facility at the UI for assistance with the VT and NOE NMR experiments, and Dr. Jerome Baudry in the School of Chemical Sciences' Computer Applications Facility at the UI for consultations and advice concerning the MM2 calculations. This work was supported by grants from the National Institutes of Health (GM 13956 to RMC and GM 054029 to JC), and from the Kentucky Agriculture Experiment Station (JC).

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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