Tris(pentafluorophenyl)borane Catalyzed Stereoselective Synthesis of β- <i>O</i> -Aryl Glycosides from Armed and Disarmed Glycosylimidate Donors

Herein, we report a stereoselective protocol for the synthesis of β<i>-O</i>-aryl glycosides from both armed and disarmed glycosylimidates with weakly nucleophilic phenolic acceptors using tris(pentafluorophenyl)borane [B(C₆F₅)₃, BCF] as a catalyst. Under mild reaction conditions, BCF not only activates armed and disarmed glycosylimidate donors but also increases the nucleophilic character of challenging phenolic acceptors to afford the desired <i>O</i>-aryl glycosides in good yield with high β<i>-</i>anomeric selectivity, while completely suppressing the formation of <i>C</i>-aryl glycosides, a common competitive side product under strong Lewis acidic conditions. The method tolerates a broad substrate scope, enabling the transformation of diverse glycosyl donors and acceptors into the corresponding glycosides without the need for additional additives. Furthermore, the catalytic system was successfully scaled up to the gram level and applied to downstream synthetic derivatizations.