A New Protocol for Stereocontrolled Lactone Annulation

Article abstract of DOI:10.1021/jo00331a052

Through regiocontrolled alkylation of cyclopentanone enolates with methyl 4-bromo-3-methoxycrotonate, base-promoted cyclization, and ketalization, α,β-unsaturated esters having a diquinane molecular framework are produced.Controlled reduction of the carbalkoxy group, application of the Claisen rearrangement, and implementation of an intramolecular Michael addition-oxidation sequence completes a scheme which leads efficiently to tricyclic lactones having structural features common to a number of sesquiterpenoid natural products.