CONFORMATIONAL-ANALYSIS OF CEMBRENENOL - APPLICATION OF H-1 AND C-13 NMR-SPECTROSCOPY AND OF COMPUTATIONAL METHODS

The solution structure of the cyclic diterpene cembrenenol was investigated. A strategy for conformational analysis is proposed which is based on computational methods and experiments to determine the structure-relevant NMR parameters. Computed and experimentally determined steady-state NOEs were compared in a first step, which served to sort out a few probable conformers. The detailed analysis of homo- and hetero-nuclear coupling information together with NOE data defining local geometries allowed, in a second step, the selection of the most probable conformation. The structure corresponds to the lowest energy structure proposed by computational methods alone. Its ring structure is in excellent agreement with the x-ray ring structure of the closely related cembrenene.