Halogen Bonding‐Mediated Glycosylation of 2,3‐Unsaturated Glycosyl Acetates via NCSCH ₂ Cl/KI

Abstract Non‐covalent interaction‐driven synthetic strategies have revolutionized carbohydrate chemistry. Halogen bonding donors are expected to significantly improve the efficiency and selectivity of carbohydrate synthesis by precisely modulating weak intermolecular interactions. In this study, we described a thiocyanato‐enhanced neutral monodentate halogen bonding donor demonstrating high efficacy in converting 2,3‐unsaturated glycosyl acetates to 2,3‐unsaturated glycosides. This donor, with cost‐efficiency and operational robustness, exhibited great potential for industrial applications. Density functional theory calculations confirmed that the iodine‐oxygen bond lengths and angles in the donor‐substrate complex align with characteristic halogen bonding parameters. Mechanistic studies further elucidated the impact of donor structural architecture and stoichiometric ratios on glycosylation efficiency. This halogen bonding donor offers a new option for constructing biologically active carbohydrate molecules.