Oxidation of carbohydrates with chromium trioxide in acetic acid. IV. Conversion of cyclic methylene acetals into cyclic carbonates

Abstract

Addition of acetic anhydride to the reagent, chromium trioxide in acetic acid, changes the outcome of the oxidation of cyclic methylene acetals, giving cyclic carbonates in addition to formyl ketones. Five-membered acetals (acetylated 3,4-O-methylene-D-mannitol and-L-iditol) give good yields of the carbonates, which are readily isolated as diisopropylidene derivatives. Six-and seven-membered acetals (acetylated 2,4-O-methylene-D-glucitol and 2,5-O-methylene-D-mannitol) give poor yields of carbonates, which are unstable under the acid conditions used for deacetylation: the carbonate group migrates or is removed.