Synthesis of Tetracyclic-Fused Dihydroindeno[2,1-b]chromenes via Palladium-Catalyzed Alkyne Insertion and C–H Bond Activation

An unprecedented Pd-catalyzed cascade alkyne insertion/Heck/C–H activation reaction of o-iodophenyl alkenyl ethers and diarylacetylenes has been developed. Diversified tetracyclic-fused dihydroindeno[2,1-b]chromenes bearing a quaternary center were constructed in an efficient, straightforward, and atom-economic way with good to excellent yields. The protocol features high bonding efficiency, operational simplicity, broad substrate scope, and easy scale-up.