A concise synthesis of sugar isoxazole conjugates

A synthesis of novel 3,5-disubstituted isoxazole–carbohydrate conjugates is described. The title compounds are obtained from 3-deoxy-3-C-nitromethyl derivatives of 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose via nitrile oxide intermediates. The developed approach provides the first examples of isoxazolyl sugars where the azole fragment is attached to C(3) of the carbohydrate through a C–C bond. Isoxazoles can be valuable linkers in glycoconjugate chemistry and this is demonstrated by the synthesis of a glycocluster containing five carbohydrate residues attached to a central glucose platform.