Evidence of rearrangement of 3-acyl derivatives of ascorbic acid to 2-acyl derivatives has been found for carbon and phosphorus acyl groups. The observations are consistent with intramolecular rearrangement through a cyclic intermediate in which the acyl group is bonded to both the 2- and 3-oxygen atoms of ascorbic acid. A rate of rearrangement has been measured for the 3-diphenylphosphinate ester. Calculated results indicate an increase in negative atomic charge at O-2 in the 3-acyl esters but a decrease in the charge of O-3 in the 2-acyl esters.