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(1)H, (13)C NMR and X-ray crystallographic studies of highly polyhalogenated derivatives of costunolide lactone.

Corona D, Díaz E, Nava JL, Guzmán A, Barrios H, Fuentes A, Hernandez-Plata SA, Allard J, Jankowski CK

Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, C.U. Coyoacán, 04510 México D.F., Mexico.

The costunolide lactone, a sesquiterpene compound isolated from Zaluzania triiloba species, reacted with several dihalocarbene sources produced by trihaloform-NaOH under successive phase transfer reactions yielding mono-, bis- and tris-dihalocyclopropane adducts. The structures, as well as the configurational assignments of the different derivatives, were established by (1)H and (13)C NMR spectroscopy and assisted by X-ray crystallographic and molecular modelling studies. The specific shielding of protons in the neighbourhood of different halogens on the cyclopropane moieties was correlated to the pseudocontact interactions.

Published 31 October 2005 in Spectrochim Acta A Mol Biomol Spectrosc, 62(1): 604-13.
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