Ring scission of cyclic acetals. Part III. Reaction of acetyl trifluoroacetate with 1,3:2,5:4,6-tri-O-methylene-D-mannitol

Abstract

The ring fission reaction of 1,3:2,5:4,6-tri-O-methylene-D-mannitol has been studied with the acetylating reagent formed from the 1 : 1 molar mixture of trifluoroacetic anhydride and acetic acid. Among a variety of acetals which have been identified are an O-acetoxymethyl-O-acetyl-1,3:2,5-di-O-methylene-, a di-O-acetoxymethyl-di-O-acetyl-2,5-O-methylene-, an O-acetyl-1,3:2,5-di-O-methylene-, 1,6-di-O-acetyl-2,5-O-methylene-, 1,6-di-O-acetyl-2,5-O-methylene-3,4-O-oxydimethylene-, and 1-O-acetyl-3-O-alkoxymethyl-2,5:4,6-di-O-methylene-compounds. Mechanisms put forward to interpret the formation of these products are based on a ring-opening reaction with the formation of an O-acetyl and an O-trifluoroacetoxymethyl reaction intermediate.