and the -orientation of H-20. In addition, according
to the ROESY correlations of H-5/H-16, H-15/H-16, H-15/H-20,
and H-17/H-14b, the relative configuration of the C-15, C-16, and
C-17 stereogenic center was deduced as R*, S*, and R*, respectively.
Thus, the structure of alstoyunine C was elucidated as 3.