Chemoenzymatic Synthesis of (+)-Asperpentyn and the Enantiomer of the Structure Assigned to Aspergillusol A

Total syntheses of (+)-asperpentyn
(1) and compound ent-2,
the enantiomer of the structure, 2, assigned to the natural
product aspergillusol A are reported.
Both reaction sequences employ the enzymatically derived and enantiomerically
pure cis-1,2-dihydrocatechol 4 as starting
material and use Sonogashira cross-coupling chemistry to install the
required enyne side-chain. The 1H and 13C NMR
spectroscopic data derived from compound ent-2 match those reported for aspergillusol A, thus suggesting
that the gross structure of this natural product has been assigned
correctly, although its absolute stereochemistry remains unclear.