Expedient Assembly of Multiantennary <i>N</i>-Glycans from Common <i>N</i>-Glycan Cores with Orthogonal Protection for the Profiling of Glycan-Binding Proteins

Complex-type <i>N</i>-glycans are structurally diverse molecules, responsible for many biological processes, yet the specific sequences of <i>N</i>-glycans involved in biological recognition remain largely unknown. Despite the recent development of many efficient chemoenzymatic approaches, it is still lacking a general approach to produce structurally diverse complex-type <i>N</i>-glycans. Here, we designed two common precursors equipped with orthogonal protecting groups for antennary differentiation and selective glycan elongation. The <i>N</i>-acetyllactosamine (LacNAc) repeat modules were synthesized separately based on iterative Au(I) promoted glycosylation and programmable one-pot strategy and were incorporated into the <i>N</i>-glycan core structure in a site-specific manner. The final removal of benzyl groups was cleanly achieved using pressurized flow chemistry. A total of 51 <i>N</i>-glycans were assembled and presented as an array to study the binding specificity toward a panel of influenza hemagglutinins and other lectins. The established method allows a rapid and previously infeasible synthesis of asymmetric bi- and triantennary <i>N</i>-glycans, especially with the LacNAc repeats residing at a specific arm, bringing in new opportunities to study carbohydrate-receptor interactions.