13C NMR studies of the friedelane series of triterpenoids and the conformation of the D and E rings in friedelan-7-one

Prakash, Om ; Roy, Raja ; Garg, H. S. ; Bhakuni, D. S. (1987) 13C NMR studies of the friedelane series of triterpenoids and the conformation of the D and E rings in friedelan-7-one Magnetic Resonance in Chemistry, 25 (1). 39 - 41. ISSN 0749-1581

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Official URL: http://www3.interscience.wiley.com/journal/1104596...

Related URL: http://dx.doi.org/10.1002/mrc.1260250110

Abstract

The 13C chemical shifts in the spectra of friedelan-7-one (1), methyl 3-oxofriedelan-25-oate (2), methyl friedelan-25-oate (3), 7-oxofriedelan-3-α-yl acetate (4), friedelan-3-one (5), 2-hydroxy-3, 4-seco-friedelan-3-oic acid (6), methyl 2-oxo-3,4-seco-friedelan-3-oate (7), methyl 2-hydroxy-3,4-seco-friedelan-3-oate (8) and 3,4-seco-friedelan-2,3-diol (9) have been fully assigned using two-dimensional heteronuclear correlation NMR spectroscopy, BB proton decoupled, DEPT and selective heteronuclear spin decoupling methods. These assignments and the observation of substantial NOEs between 26-methyl and 28-methyl and between 28-methyl and 30-methyl support the boat to boat conformations for the D and E rings in 1. Corrections and correlations are made of some earlier literature assignments of friedelanones.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons, Inc.
Keywords:13C NMR; Friedelanes; Triterpenoids; D/E Ring Conformation
ID Code:2352
Deposited On:07 Oct 2010 14:41
Last Modified:16 May 2011 12:51

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