An efficient method for selective acetylation of alcoholic hydroxyl groups.

Abstract

Acetylation of the C-6 hydroxyl group in oridonin (1), which is difficult by the use of acetic anhydride in pyridine, was investigated using acetic anhydride in the presence of some Lewis acids. A reagent system of acetic anhydride in the presence of a catalytic amount of boron trifluoride etherate was shown to be effective for this purpose. This reagent system was shown to be useful for selective acetylation of the alcoholic group (s) in compounds which have both alcoholic and phenolic hydroxyl groups.