Synthesis of (+)-Omphadiol and (+)-Pyxidatol C

The synthesis of
(+)-omphadiol and (+)-pyxidatol C was achieved
through two independent strategies. For the synthesis of (+)-omphadiol,
dicyclopentadienone was used as the workbench on which the three contiguous
stereocenters of the cyclopentane could be introduced selectively.
These include a tertiary alcohol and a selective protonation of an
enolate. A ring-closing metathesis and a cyclopropanation concluded
the synthesis. For the synthesis of pyxidatol C, we used the epoxide
derived from (R)-linalool that was transformed to
cyclopentane 23. After chain extension, another ring-closing
metathesis followed by oxidation state changes and finally a cyclopropanation
led to (+)-pyxidatol C.