Novel synthesis of pleurospiroketals A and B and direct conversion of pleurospiroketal A into pleurospiroketals D, E, and F

Pleurospiroketals A–F, highly oxygenated sesquiterpenes isolated from edible mushrooms Pleurotus cornucopiae and P . citrinopileatus , share an unprecedented and characteristic benzannulated 5,5-spirocyclic ring system. We achieved a novel and concise synthesis of pleurospiroketals A and B from commercially available (–)-perillaldehyde via diastereoselective dihydroxylation, Stille cross-coupling, and intramolecular acetal formation triggered by dihydrofuran oxidation. In addition, we accomplished the direct conversion of pleurospiroketal A into pleurospiroketals D, E, and F by using Crabtree’s catalyst-mediated diastereoselective hydrogenation or olefin isomerization.