Synthesis of C-glycosides enabled by palladium-catalyzed glycosylation reactions

C-Glycosides represent a privileged class of carbohydrates, which exhibit remarkable biological and pharmaceutical activities. Transition metal-catalyzed cross coupling reaction is a powerful tool for the efficient and rapid construction of C-C bonds. Among various transition-metal catalyzed methods, palladium-catalyzed C-glycosylation is an effective and reliable approach to synthesize C-glycosides, which involves the reaction of glycoyl donors and various reaction partners via C-C glycosidic bond formation under mild conditions with high regio/stero-selectivities. In this review, palladium-catalyzed C-glycosylation reactions are summarized and discussed in detail with the focus on the synthesis of C-aryl glycosides, C-alkyl glycosides, C-alkenyl glycosides, and other functionalized C-glycosides since 2020 to 2024. Some representative synthetic strategies and their transformation application along with reaction mechanisms are also highlighted.