Emerging Organometallic Methods for the Synthesis of C‐Branched (Hetero)aryl, Alkenyl, and Alkyl Glycosides: C−H Functionalization and Dual Photoredox Approaches

Abstract

Transition‐metal‐catalyzed C−H functionalization and photoredox nickel dual catalysis have emerged as innovative and powerful avenues for the synthesis of C‐branched glycosides. These two concepts have been recently established and provide efficient and mild methods for accessing a series of valuable complex C‐branched glycosides of great interest. Herein, recent developments in the synthesis of C‐branched aryl/alkenyl/alkyl glycosides through these two approaches are highlighted.

Diastereoselective Pd-Catalyzed Anomeric C(sp3)–H Activation: Synthesis of α-(Hetero)aryl C-Glycosides

“…The persistent need from drug discovery programs for elaborate complex C-aryl glycosides has led to pioneering developments in the C-H functionalization 17 which avoided the pre-activation of the aryl partners in the glycosylation reaction. In this context, several groups have reported efficient methods by using activation of C(sp 2 )-H bond of aromatic substrates with sugar partners (Scheme 1-b).…”

Iridium‐Catalyzed Hydroarylation via C−H Bond Activation

“…[15] Transition-metal-catalyzed C-glycosylations in-volving CÀ H activation are of great interest to achieve atomeconomical synthesis of such useful compounds. [16] In this respect, we focused on glycals, which represent sugar derivatives having a cyclic vinyl ether moiety, and we expected that the hydroarylation of glycals might become an efficient way to the C-glycosyl arenes.…”

Directed Nickel‐Catalyzed pseudo‐Anomeric C−H Alkynylation of Glycals as an Approach towards C‐Glycoconjugate Synthesis

“…The introduction of alkyne moieties was unsuccessful in these conditions. In the literature, C−H functionalization of sugars are very limited [12] . This reactivity, applied on glycals in the absence of a directing group, led almost exclusively to the functionalization of the position 2 with perfluoroalkylated, alkene‐type or borylated functionalities only (Scheme 1).…”