Aldehyde‐Mediated Open‐Air Stereoselective β‐Glycosylation of Glycals: An Expeditious Route towards Glycosyl‐Ester Synthesis

Abstract The study introduces a method for achieving a selective synthesis of β‐glycosyl esters through the reaction of glycals with carboxylic acids. This process is characterized by stereoselectivity, operating under mild reaction conditions and in an open‐air environment mediated by an aldehyde. Detailed investigations and control experiments indicate the significance of benzaldehyde in conjunction with atmospheric air in facilitating this transformation. The method's versatility is evident in its broad substrate scope, accommodating various carboxylic acid derivatives with electron‐releasing and electron‐neutral functional groups. The practical applicability of the protocol is demonstrated by successfully esterifying different drugs, including indomethacin, tolmetin, and stearic acid, resulting in the production of novel compounds with excellent yields. Mechanistic studies, supported by controlled experiments, highlight the formation of glycal epoxide as an intermediate in the reactions.