We report the first
total syntheses of (+)-isolaurenidificin (1) and (−)-bromlaurenidificin
(2), the
latest acetogenins of the 2,6-dioxabicyclo[3.3.0]octane class. The
synthesis features a completely stereoselective one-pot epimerization-ring
contraction to establish the cis configuration with respect to C10–H
and C12–H of the tetrahydrofuran ring. Six stereogenic centers
and an olefin geometry were constructed in a highly stereoselective
manner. Absolute configurations of the natural products were deduced
by the comparison of NMR data and specific rotations.