Construction of Nine-Membered Heterocycles through Palladium-Catalyzed Formal 5+4 Cycloaddition

摘要

The first catalytic formal 5+4 cycloaddition to prepare nine-membered heterocycles is presented. Under palladium catalysis, the reaction of N-tosyl azadienes and substituted vinylethylene carbonates (VECs) proceeds smoothly to produce benzofuran-fused heterocycles in uniformly high efficiency. Highly diastereoselective functionalization of the nine-membered heterocycles through peripheral attack is also demonstrated.