Characterization of stereochemistry and molecular conformation using solid-state NMR tensors.
A solid-state NMR technique is described for establishing stereochemistry using the natural product terrein as a model compound. This method involves comparison of experimental (13)C tensor principal values with ab initio computed values for all possible computer-generated stereoisomers. In terrein the relative stereochemistry is confirmed by NMR to be 2R*,3S with high statistical probability (>99.5%). The proposed approach also simultaneously verifies the molecular conformation of the two hydroxy groups in terrein established by X-ray data. It is sufficient to use only shift tensor values at carbons 2 and 3, the stereocenters, to characterize both the stereochemistry and molecular conformations. The solid-state NMR method appears to be especially useful for determining relative stereochemistry of compounds or their derivatives that are difficult to crystallize.
Harper
J K
JK
Department of Chemistry, University of Utah, Salt Lake City, 84112, USA.
Mulgrew
A E
AE
Li
J Y
JY
Barich
D H
DH
Strobel
G A
GA
Grant
D M
DM
D002247:Carbon Isotopes; D003517:Cyclopentanes / Q000737:chemistry*; D005658:Fungi / Q000737:chemistry; D008968:Molecular Conformation; D009183:Mycotoxins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
D002247:Carbon Isotopes; D003517:Cyclopentanes; D009183:Mycotoxins; C439087:terrein