Carbon-13 assignments and revision of the stereostructures of the Cadinanes 2-Hydroxy-8α-angeloyloxycalamenene and 2-Hydroxy-8α-hydroxycalamenene

The two known cadinanes 2-hydroxy-8α-hydroxycalamenene and 2-hydroxy-8α-angeloyloxycalamenene were isolated from a Louisiana population of Heterotheca subaxillaris. Their 13C NMR spectra were fully assigned by the application of HETCOR, COLOC, COSY, NOESY and DEPT experiments. It was shown on the basis of NOESY experiments that both cadinanes require revision at the stereogenic centre C-7

GC/MS evaluation of compounds in dry and conditioned Striga species seeds

We have analyzed the dichloromethane (CH2Cl2) extracts of seeds of dry and conditioned Striga hermonthica (Del.) Benth., S. aspera (Willd.) Benth., and S. gesnerioides (Willd.) Vatke by means of gas chromatography (GC) coupled to mass spectrometry (MS). Sixteen compounds were identified on the basis of their mass spectra and their retention indices. All Striga spp. extracts contained tetradecanoic acid, cis,cis-9,12-octadecadienoic acid, cis-9-octadecenoic acid, and sitosterol. Also, 2,6-dimethoxy-p-benzoquinone (2,6-DMBQ) and several long chain aldehydes and n-hydrocarbons were detected in some of the extracts. The nature of the chemical changes induced by seed conditioning is discussed

13CNMR assignments for methyls and quarternary carbons of the limonoid abacunone

The high field1H and13C resonances of obacunone were established by a series of I D and 2D NMR experiments. The13C-NMR signals of the five tertiary methyl groups and all quatenary carbons were unambiguously assigned. The results confirm the stereochemical assignments at all stereogenic centres