Improved stereoselective synthesis of both methyl α- and β-glycosides corresponding to the amino sugar component of the E Ring of calicheamicin γ1I and esperamicin A1
monosaccharide component (α and β-anomer) of the E Ring of calicheamicin γ1I and esperamicin A1 has been synthetized by an efficient and improved stereoselective procedure starting from methyl 2-deoxy-α- and β-D-ribopyranoside. The synthetic procedure makes use, in each case, of a cyclic sulphate and of the regioselectiveringopening of an intermediate activated aziridine.