Abstract
The structure and absolute configuration of valeranone have been established as V from the following evidence. Valeranone (V) was converted into IX via VIII (R=O, X=H), and β-eudesmol (X ; R=CH2) into XVI via XV (X=H). VIII (R=O, X=H) was shown to be a diastereomer of XV (X=H), and IX the enantiomer of XVI, thus establishing the absolute configuration of the C-10 methyl as α and that of the C-7 isopropyl group as β. The absolute configuration of the C-5 methyl was confirmed to be α by observing a negative Cotton effect of XXI, the difference of the nuclear magnetic resonance signals of the C-5 methyl of V and XXIV, and the conversion of XXII into XXIII. The absolute stereochemistry was also supported by the nuclear magnetic resonance spectra of XXVI (R=H and Ac) which revealed that the C-4 hydroxyl of R-configuration was located in a 1, 3-diaxial relation to the C-10 methyl group.
