Eight‐Membered Palladacycle Intermediate Enabled Synthesis of Cyclic Biarylphosphonates

Abstract Transition‐metal‐catalyzed coupling reactions that involve the direct functionalization of insert C−H bond represent one of the most efficient strategies for forming carbon‐carbon bonds. Herein, a palladium‐catalyzed intramolecular C−H bond arylation of triaryl phosphates is reported to access seven‐membered cyclic biarylphosphonate targets. The reaction is achieved via a unique eight‐membered palladacyclic intermediate and shows good functional group compatibility. Meanwhile, the product can be readily converted into other valuable phosphate compounds.