Stereoselective Synthesis of β-Glycosyl Esters via TBHP-Mediated Oxidative Coupling of Aldehydes and Cyclic Enol Ethers

A TBHP-mediated, metal-free strategy has been developed for the direct one-step synthesis of glycosyl esters from readily available glycals and aldehydes. This protocol proceeds under mild conditions and enables the highly stereoselective formation of β-glycosyl esters in excellent yields. It features a broad substrate scope, good functional group tolerance, and compatibility with structurally complex molecules. Furthermore, the method delivers high yields even on a gram scale, underscoring its practical utility in synthetic applications. Mechanistic investigations and control experiments indicate that the reaction proceeds through a free radical pathway involving the initial generation of peracids. These peracids react with glycals to produce a glycal epoxide intermediate, which subsequently undergoes nucleophilic attack by the acids released from peracids, affording the desired β-glycosyl esters.