The 1H and 13C NMR chemical shift of ring C and D and of the
lactonic side-chain are almost identical to withametelin (7)
(Oshima et al., 1987), also isolated in this work. This comparison
is important since the absolute stereochemistry of compound 7
was indirectly determined by a X-ray crystallographic analysis
(Shingu et al., 1990). Thus, the relative configuration of the sidechain,
which was difficult to establish from NOESY data, could be
deduced to be the same as the compound 7. Furthermore,