Palladium-catalyzed oxaspirocyclizations

Article abstract of DOI:10.1016/S0040-4020(01)80776-6

Palladium-catalyzed oxidation of 1-(3-hydroxyalkyl) and 1-(4- hydroxyalkyl)-1,3-cycloalkadienes results in a stereocontrolled oxaspirocyclization. The reaction proceed via a spirocyclic (π- allyl)palladium intermediate, which is attacked by an acetate or a chloride nucleophile leading to an overall 1,4-addition across the diene. The intermediate (π-allyl) palladium complex was independently prepared and characterized. The stereochemistry of the 1,4-addition can be controlled to give either cis or trans 1,4-addition across the double bonds. The oxaspirocyclization was applied to the total synthesis of theaspirone.