Au-Catalyzed 1,3-Acyloxy Migration/Cyclization Cascade:A Direct Strategy toward the Synthesis of Functionalized Abietane-Type Diterpenes

A direct strategy toward the synthesis of functionalized abietane-type diterpenes and related polycyclic molecules was developed through an Au-catalyzed 1,3-acyloxy migration/cyclization/electrophilic aromatic substitution cascade.Unlike the known polyene-type cyclization strategies for the construction of abietane-type diterpene skeletons,propargylic ester groups were used for the cyclization process,which can readily lead to the key skeleton with C2 and C3 functionalization.As a demonstration of the potential application of this tandem reaction,a collective total synthesis of(±)-2-ketoferruginol,(±)-fleuryinol B,(±)-salviol,(±)-2β-acetoxyferruginol,and(±)-2β-acetoxysugiyl methyl ether was achieved.Among these molecules,(±)-fleuryinol B and(±)-2β-acetoxyferruginol were synthesized for the first time.