Stereoselective Access to Polyfunctionalized Nine-Membered Heterocycles by Sequential Gold and Palladium Catalysis.

We report herein a gold and palladium sequential catalysis system to access furan-fused nine-membered heterocycles in high efficiency and enantioselectivity. In this one-pot procedure, easily accessible enynamides undergo cyclization to generate azadienes in situ that participate in enantioselective formal [5+4] cycloaddition with vinyl ethylene carbonates. Conformation-controlled highly diastereoselective derivatizations of these medium-sized rings, coupled with oxidative furan cleavage, have enabled the access to diverse densely-functionalized nine-membered lactams.