Palladium-catalyzed intramolecular reductive cross-coupling of Csp ²-Csp³ bond formation

A Pd-catalyzed efficient reductive cross-coupling reaction without metallic reductant to construct a Csp²-Csp³ bond has been reported. A Pd^IV complex was proposed to be a key intermediate, which subsequently went through double oxidative addition and double reductive elimination to produce the cross-coupling products by involving Pd ^0/II/IV in one transformation. The oxidative addition from Pd ^II to Pd^IV was partially demonstrated to be a radical process by self-oxidation of substrate without additional oxidants. Furthermore, the solvent was proved to be the reductant for this transformation through XPS analysis.