A Reagent for Selective Deprotection of Alkyl Acetates

The use of magnesium methoxide for selective deprotection of alkyl esters is described. By adjusting the equivalents of the magnesium methoxide reagent, it is possible to selectively cleave primary acetate in the presence of secondary and tertiary acetate and to cleave secondary acetate in the presence of tertiary acetate. A high selectivity can also be obtained for the same primary acetates if the β-positions of the acetates render a different steric bulkiness. This mild reagent has been successfully applied to the selective deprotection of many natural-occurring molecules including hydroxycitronnellol diacetate, trans -sobrerol diacetate, betulin diacetate, and baccatin III.