Two‐dimensional NMR spectra of sesquiterpenes. II—Noesy study of some sesquiterpene lactones with pseudoguaianolide, 3,4‐seco‐pseudoguaianolide and guaianolide skeletons

Abstract The application of phase‐sensitive 2D 1 H NOE NMR spectroscopy (PS NOESY) in the stereochemical assignment of sesquiterpene lactones such as 4‐oxo‐3,4‐ seco ‐ambrosan‐6,12‐olide‐3‐oic acid methyl ester, 4‐oxo‐6‐hydroxypseudoguai‐11(13)‐en‐8,12‐olide and 8‐angeloyloxy‐10‐acetoxyguai‐3‐en‐6‐,12‐olide is reported.