Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

Diglycose derivatives, consisting of two monosaccharides linked at non-anomeric positions by a bridging nitrogen atom, have been synthesised. Conversion of one of the precursor monosaccharide coupling components into an unsaturated derivative enhances its electrophilicity at the allylic position, facilitating coupling reactions. Mitsunobu coupling between nosylamides and 2,3-unsaturated-4-alcohols gave the 4-amino-pseudodisaccharides with inversion of configuration as single regio- and diastereoisomers. A palladium-catalysed coupling between an amine and a 2,3-unsaturated 4-trichloroacetimidate gave a 2-amino-pseudodisaccharide as the major product, along with other minor products. Derivatisation of the C=C double bond in pseudodisaccharides allowed the formation of Man(N4–6)Glc and Man(N4–6)Man diglycosides. The amine-linked diglycosides were found to show weak glycosidase inhibitory activity.