Insertion of Glycosylidene Carbenes into Phenolic O–H Bonds for the Synthesis of <i>O</i>-Aryl Glycosides

We present a new strategy for the synthesis of <i>O</i>-aryl glycosides through the formal insertion of glycosylidene carbenes into the O-H bond of phenols. The key glycosylidene carbene intermediates were generated <i>in situ</i> by copper-catalyzed oxidation of bench-stable glycosylidene diaziridine precursors. This method enables the glycosylation of a variety of phenols with good yields, excellent diastereoselectivity, and chemoselectivity, providing a highly practical method for the late-stage glycosylation of complex natural products and bioactive agents.