Rhodium(II)/Chiral Phosphoric Acid‐Cocatalyzed Enantioselective O–H Bond Insertion of α‐Diazo Esters

A rhodium(II)/chiral phosphoric acid system has been developed for the asymmetric catalytic insertion of α‐diazo esters into the O–H bond of carboxylic acids to generate an array of synthetically useful α‐hydroxy ester derivatives in good ee (up to 95% ee). Furthermore, the substrate scope could be successfully extended to a range of phenols and alcohols with high yield (up to 92%) and excellent enantioselectivity (up to 97%) under mild reaction conditions. Additionally, a density functional theory (DFT) study was performed to elucidate the reaction mechanism. magnified image