Palladium-Catalyzed alpha-Arylation of Cyclic Vinylogous Esters for the Synthesis of gamma-Arylcyclohexenones and Total Synthesis of Aromatic Podocarpane Diterpenoids

Abstract

Described is a method for the formal gamma-arylation of cyclohexenones allowing synthesis of a remote all-carbon quaternary center. The process involves the palladium-catalyzed alpha-arylation of a alpha-substituted cyclic vinylogous ester followed by the Stork-Danheiser transposition. The synthetic utility of this protocol is featured in the total syntheses of (+/-)-12-hydroxy-13-methylpodocarpa-8,11,13-trien-3-one, (+/-)-3 beta,12-dihydroxy-13-methylpodocarpane-8,11,13-triene, and (+/-)-O-methyl nimbinone.