Abstract
Half-esters are very important synthetic building blocks. They are commonly prepared by monohydrolysis of symmetric diesters. However, successful distinction of the two identical ester groups has been a challenging task. Enzyme reactions do not provide any basis for prediction of the reactivities. Classical saponification reactions typically produce a slurry mixture of the starting diester, dicarboxylic acid and a small amount of the half-ester, and the separation is very difficult. However, earlier, we reported a highly efficient and practical selective monohydrolysis of symmetric diesters with the use of THE and aqueous NaOH or KOH at 0°c. The reaction mixtures are quite clean, and therefore even when the yields are less than quantitative, the isolation and purification of the resultant half-esters is straightforward. The procedure is simple, and reaction conditions are mild and environmentally friendly, and therefore synthetic versatility of this selective monohydrolysis is anticipated. This review article describes the current progress and the scope of this selective monohydrolysis reaction.
