DFT molecular modeling and NMR conformational analysis of a new longipinenetriolone diester

The structure and conformational behavior of the new natural compound (4R,5S,7S,8R,9S,10R,11R)-longipin-2-en-7,8,9-triol-1-one 7-angelate-9-isovalerate (1) isolated from Stevia eupatoria, were studied by molecular modeling and NMR spectroscopy. A Monte Carlo search followed by DFT calculations at the B3LYP/6-31G* level provided the theoretical conformations of the sesquiterpene framework, which were in full agreement with results derived from the 1H-1H coupling constant analysis.