Base-catalyzed Degradations of Carbohydrates. X. Degradation by β-Elimination of Methylated Degraded Leiocarpan A

Abstract

Treatment of methylated degraded leiocarpan A with l,5-diazabicyclo[5.4.0]undec-5-ene and acetic anhydride, followed by mild acid hydrolysis and de-O-acetylation, furnishes 3,4,6-tri-O-methyl-D-mannose and 3,4-di-O-methyl-6-O-(2,3,4-tri-O-methyl-β-D-xylopyranosyl)-D-mannose. The characterization of the methylated disaccharide provides evidence for the site of attachment and anomeric configuration of the D-xylopyranose end groups in the parent polysaccharide.