Simultaneous application of the nuclear Overhauser effect and an N.M.R. shift reagent. Conformation of costunolide and dihydrocostunolide in solution

Abstract

Conformations of the ten-membered ring sesquiterpene lactones costunolide (1) and dihydrocostunolide (2) in [²H]chloroform have been determined by intramolecular inter-nuclear Overhauser effect measurements in the presence of an n.m.r. lanthanide shift reagent, [²H₂₇]Eu(fod)₃; care must be taken in applying these techniques simultaneously.