Effective, direct biomimetic synthesis of dibenzocyclooctene lignans by hypervalent iodine oxidation of phenolic dibenzylbutyrolactones

Readily available trans-2,3-dibenzylbutyrolactones are converted in high yields via 4-hydroxycyclohexa-2,6-dienones into dibenzocyclooctene lignans by treatment with phenyliodonium diacetate in aqueous methanol followed by trifluoroacetic acid.