Double C−H Activation and Palladium Migration Enabling a Domino Synthesis of Polycyclic Heterocycles

Polycyclic quinolinones are recognized as important structural scaffolds; however, most existing synthetic methods from α-bromocarbonyl compounds proceed through an entirely radical process, whereas other distinctive reaction modes remain underdeveloped. In this work, a palladium-catalyzed domino synthesis of polycyclic quinolinone scaffolds from α-bromocarbonyl compounds has been developed. This method provides a straightforward approach to access a wide range of polycyclic quinolinone derivatives in high yields and is also applicable for the modification of various bioactive molecules and drugs. The palladium catalytic cycle in this transformation involves an intramolecular C−H/C−H coupling, proceeding through double C−H activation, 1,4-palladium migration, and alkene stereoisomerization. Preliminary mechanistic studies and DFT calculations have been performed to support the plausible reaction pathway.