Chemical Modification of Maltotriose

Hot acetylation of maltotriose with acetic anhydride and sodium acetate led to the formation of an anomerically unsubstituted maltotriose decaacetate (2.8% yield) in amorphous form in addition to the principal product, β-maltotriose hendecaacetate (80% yield). The structure of the decaacetate was elucidated by chemical reactions and n.m.r. spectroscopy. α-Maltotriose hendecaacetate and deca-O-acetyl-α-maltotriosyl chloride were prepared to facilitate the structural assignment. From measurement of the optical rotation, it was assumed that the decaacetate is a mixture of both anomers in a constant proportion. The decaacetate was also obtained either by treatment of the β-hendecaacetate with hydrogen bromide in acetic acid followed by warm aqueous sodium acetate or by the reaction of the β-hendecaacetate with piperidine in tetrahydrofuran.