Characterization of alkaline-degradation products of some 3,4-di- and 3,4,6-tri-methyl ethers of hexoses by G.L.C.-mass spectrometry of O-trimethylsilyl derivatives

Abstract

G.l.c.-mass spectrometry has been used to provide information on the O-trimethylsilyl derivatives of the products of alkaline degradation of 3,4-di- and 3,4,6-tri- O-methyl- D-glucose, and 3,4,6-tri- O-methyl- D-galactose. During reaction with sodium hydroxide-sodium borohydride mixtures, reduction occurs more rapidly than β-elimination and the only detectable products were the corresponding alditols and the epimeric 3-deoxyalditols. Extended reaction with sodium hydroxide alone, followed by treatment with sodium borohydride, gives mixtures of aldonic acids including the epimeric 3-deoxy-4- O-methylaldonic acids (metasaccharinic acids), 3-deoxyaldonic acids (with loss of the 4- O-methyl substituent), and 3,4-dideoxy-aldonic acids. Possible reaction-pathways are discussed.