Directed Nickel?Catalyzed <i>pseudo</i> ?Anomeric C?H Alkynylation of Glycals as an Approach towards <i>C</i> ?Glycoconjugate Synthesis

The synthesis of complex C-glycoconjugates is presented here using a key directed nickel-catalyzed C?H alkynylation step. Thanks to bidentate amidoquinoline-type directing group, the insertion diverse alkynyl moieties onto pseudo-anomeric position glycal substrates was performed on ten examples in moderate good yields. These platforms were used as starting click reaction with azides form original C-glycoconjugates. By this route, C-glycosylated amino acid, C-linked disaccharide and biotin derivative synthesized. Preliminary conditions remove group are also proposed.