Communication: Blocked Disaccharide Analogs Bearing an Oxyimino Interglycosidic Bridge

Abstract

Oligosaccharide units in which a ONH group replaces the usual oxy bridge have been encountered in nature, for ex. in the antitumor antibiotic calicheamicin γ^1,2 and the biological importance of this peculiar interglycosidic junction has been emphasized.³ The N-O bond is very different from the bonds habitually found in carbohydrate chemistry, owing, in particular, to its weakness and the presence of lone-pairs on its two hetero atoms. These characteristics considerably affect the conformational properties of molecules like calicheamicin. As we have developed,⁴ in the CHARMm force field,⁵ parameters pertaining to this bond, we needed models of disaccharides of this type to fit computed results in with experimental data. These O-N-disaccharide derivatives were easily obtained from the O-aminosugar derivative 1.⁶