Concise Route to Triquinanes from Pyran-2-ones

Treatment of ether-bridged cyclooctatrienes (formed via intramolecular [4 + 4]-photocycloaddition of pyran-2-ones bearing pendent furans, followed by thermal decarboxylation) with excess MeLi furnishes triquinane ring systems via an apparent sequence of β-elimination, 1,5-hydrogen shift, and transannular aldolization.