Asymmetric synthesis of bis-tetrahydrofuran cores in annonaceous acetogenins.

The bis-THF cores of annonaceous acetogenins were synthesized using (3R,4R)-1,5-hexadiene-3,4-diol (1) as the sole source of carbon atoms. The methylene acetal function was applied as a new linker/tether to facilitate the ring-closing metathesis.