Synthesis of <i>C</i>‐Oligosaccharides through Versatile C(sp³)−H Glycosylation of Glycosides

Abstract

Abstract C‐ oligosaccharides are pharmacologically relevant because they are more hydrolysis‐resistant than O ‐oligosaccharides. Despite indisputable advances, C ‐oligosaccharides continue to be underdeveloped, likely due to a lack of efficient and selective strategies for the assembly of the interglycosidic C−C linkages. In contrast, we, herein, report a versatile and robust strategy for the synthesis of structurally complex C ‐oligosaccharides via catalyzed C(sp 3 )−H activations. Thus, a wealth of complex interglycosidic (2→1)‐ and (1→1)‐ C ‐oligosaccharides becomes readily available by palladium‐catalyzed C(sp 3 )−H glycoside glycosylation. The isolation of key palladacycle intermediates and experiments with isotopically‐labeled compounds identified a trans‐ stereoselectivity for the C(sp 3 )−H glycosylation. The glycoside C(sp 3 )−H activation manifold was likewise exploited for the diversification of furanoses, pyranoses and disaccharides.