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.