3.23 Carbon–Carbon σ-Bond Formation via C[sbnd]H Bond Functionalization

Abstract

Transition-metal-catalyzed CH functionalization has gained considerable interest and made noticeable progress during the past decades, because of its attractive advantages over traditional organic reactions relying on the transformation and conversion of functional groups. In this context, carbon–carbon σ-bond formation via CH activation has been a major focus of studies. In the presence of transition metals as catalysts, CH bonds can be transformed into CC bonds by reacting with a variety of reaction partners employed in traditional transition-metal-catalyzed cross-coupling reactions, including (pseudo)halides, organometallics, CC multiple bonds, and polar multiple bonds. Furthermore, dual CH activation has also gained much attention because it produces no chemical wastes other than hydrogen. A wide array of transition metals have been shown to be effective for CC bond formation via CH activation, which not only include palladium, rhodium, and ruthenium catalysts but also less expensive and toxic copper, iron, and nickel complexes.