Synthesis of the Hexasaccharide Fragment of Landomycin A:  Application of Glycosyl Tetrazoles and Phosphites in the Synthesis of a Deoxyoligosaccharide

Abstract

The synthesis of the hexasaccharide fragment of the antitumor antibiotic landomycin A ( 1 ) (aka. NSC 639187) is described. The stereocontrolled introduction of key glycoside linkages relies on the combined application of glycosyl tetrazoles and phosphites to establish α and β glycosidic linkages, respectively. Spectral comparison of landomycin A octaacetate ( 2 ) and hexasaccharide pentaacetate ( 3 ) serves to corroborate the assigned structure of 1 within the oligosaccharide domain.