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Pure Appl. Chem., Vol. 70, No. 11,
pp. 2134, 1998
Development of synergistic NMR and molecular
mechanics - Strategies for determining natural product stereochemistry*
Thomas R. Hoye,2 Seif-Eldin N. Ayyad,1
Andrew S. Judd,2 Dmitry O. Koltun,2 and Matthew
K. Renner2
1. Chemistry Department, Faculty of Science, Mansoura University,
New Dammiatta, Egypt
2. Department of Chemistry, University of Minnesota, Minneapolis,
MN 55455
E-mail: [email protected]
Abstract: Techniques that exploit straightforward aspects
of NMR spectroscopy combined with conformational analysis are being
developed in our laboratory. These studies are often driven by a
need for new methods for determination of stereochemistry in various
natural products. Both coupling constant-based and chemical shift-based
NMR methods are interpreted with the help of a thorough analysis
of families of conformations identified by appropriate molecular
mechanics treatments. This often results in solutions to structure
assignment problems that are not addressable by multi-dimensional
NMR approaches.
Selected examples of this strategy, such as those
outlined below, will be described:
-
a study of the relative configuration of two,
isomeric, 4-methylene-2-cyclohex-enones of constitution 1,
isolated from Ottelia alismoides found in the delta region
of the Nile River.
-
a general method for the assignment of absolute
configuration of b -chiral carboxylic acids (2).
-
a general method for the determination of absolute
configuration of substituted, cyclic amines (cf., 3).
* Invited lecture presented at the International
Conference on Bioversity and Bioresources: Conservation and
Utilization, 23-37 November 1997, Phuket, Thailand.
Page last modified 15 April 1999.
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