Furanose derivatives of 3-deoxy-D-manno-oct-2-ulosonic acid

Abstract

Acylation of methyl 3-deoxy-D-manno-oct-2-ulosonate leads essentially to furanose derivatives, whereas acetylation of the free acid or of its ammonium salt gives pyranose derivatives. Upon treatment with HBr in acetic acid, the pentabenzoate of methyl 3-deoxy-D-manno-oct-2-ulofuranosonate yielded a crystalline 2-bromo-derivative which, when treated with MeOH–Ag₂CO₃ was transformed into a single methyl furanoside of undetermined anomeric configuration. Reaction of methyl 3-deoxy-D-manno-oct-2-ulosonate with MeOH in the presence of an acidic catalyst gives a mixture of pyranoside(s) and furanosides separable by g.l.c.; they can be identifed by the characteristic fragments at m/e 217 for the furanosides and m/e 158 for the pyranoside(s).