CONFORMATIONAL ANALYSIS OF SOME METHYL 2,3-ANHYDROGLYCOPYRANOSIDES AND 3,4-ANHYDROGLYCOPYRANOSIDES

Proton magnetic resonance spectroscopy is used to define the conformation of a series of methyl 2,3- and 3,4-anhydroglycopyranosides. The compounds examined are shown to have conformations in solution similar to the half-chair conformation of cyclohexene, and evidence is obtained to explain the results of previous experiments on the base-catalysed equilibration between the 2,3- and 3,4-anhydro-compounds.