Pd-catalyzed cascade cyclization of allenylethylene carbonates and indandiones: Synthesis of tetracyclic dihydrocyclopentaindenofuranone derivatives

A palladium-catalyzed cascade cyclization of allenylethylene carbonates with 1,3-indandiones was developed, providing biologically interesting tetracyclic dihydrocyclopentaindenofuranone derivatives having three contiguous quaternary carbon centers in moderate to high yields with excellent diastereoselectivities. In this reaction, the allene moiety was fully fused into the cyclopentene ring.