Title page for ETD etd-052199-161956


Type of Document Master's Thesis
Author Lennox, William J
URN etd-052199-161956
Title Isolation, Characterization, and Molecular Modeling Studies on Diterpenes From Marine Organisms Withing the Eunicea Genus
Degree Master of Science
Department Chemistry
Advisory Committee
Advisor Name Title
Kingston, David G. I. Committee Chair
Calter, Michael A. Committee Member
Dorn, Harry C. Committee Member
Gandour, Richard D. Committee Member
Keywords
  • molecular modeling
  • diterpene
  • NMR
  • natural products
Date of Defense 1999-05-19
Availability restricted
Abstract
ISOLATION, CHARACTERIZATION, AND MOLECULAR

MODELING STUDIES ON DITERPENES FROM MARINE

ORGANISMS WITHIN THE EUNICEA GENUS

William J. Lennox

Mass spectrometry was used in conjunction with

numerous 1-D and 2-D NMR techniques to determine

the structures, devoid of stereochemistry, of five

different compounds isolated from the extracts of

Eunicea succinea, Eunicea tourneforti, and an

unidentified species isolated from the Eunicea

genus by Professor Meledath Govindan, of the

University of the Virgin Islands. Three of the

compounds were then identified as the known

compounds eunicin, 12,13-bisepieupalmerin,

and 7(S),8(S)-epoxy-1(S),11(R)-dolabella-3E,12(18)

-dien-13-one by comparison of their spectroscopic

data and optical rotations with those published in

the literature. Optical rotations could not be

measured accurately for the other two compounds

because of small sample sizes; therefore, another

method had to be found to elucidate the

stereochemistry of these two structures.

To solve this problem, molecular modeling

and NOESY were employed. Comparison of the NOESY

interactions to the thermodynamically available

conformations of several possible stereoisomers,

calculated by molecular modeling, proved to be a

useful technique. One of the remaining two

structures was identified as the known

stereoisomer euniolide. The stereochemistry of

the one remaining structure could not be assigned

because sample size was not large enough to

obtain a clean NOESY spectra. Finally, based on

published synthetic work by Corey and Kania,

the absolute stereochemistry of the dolabellane

was revised to 7(R),8(R)-epoxy-1(R),11(S)-

dolabella-3E,12(18)-dien-13-one.

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