Recent Advances in Palladium-Catalyzed Bridging C–H Activation by Using Alkenes, Alkynes or Diazo Compounds as Bridging Reagents
Fulin Zhang, Luoting Xin, Saihu Liao, Xueliang Huang, Yinghua Yu
Abstract
Abstract Transition-metal-catalyzed direct inert C–H bond functionalization has attracted much attention over the past decades. However, because of the high strain energy of the suspected palladacycle generated via C–H bond palladation, direct functionalization of a C–H bond less than a three-bond distance from a catalyst center is highly challenging. In this short review, we summarize the advances on palladium-catalyzed bridging C–H activation, in which an inert proximal C–H bond palladation is promoted by the elementary step of migratory insertion of an alkene, an alkyne or a metal carbene intermediate. 1 Introduction 2 Palladium-Catalyzed Alkene Bridging C–H Activation 2.1 Intramolecular Reactions 2.2 Intermolecular Reactions 3 Palladium-Catalyzed Alkyne Bridging C–H Activation 3.1 Intermolecular Reactions 3.2 Intramolecular Reactions 4 Palladium-Catalyzed Carbene Bridging C–H Activation 5 Conclusion and Outlook