Total synthesis of 3-O-demethylsporaricin A

The novel, semisynthetic pseudodisaccharide antibiotic, 3-O-demethylsporaricin A, was synthesized via 3-O-demethylsporaricin B obtained by glycosidation of its aminocyclitol part. The aminocyclitol part was synthesized as D,L-form from D,L-(1,2,3/4,5,6)-1,4-bis(benzyloxy-carbonylamino)-5,6-O-isopropyl idene-2,3,5,6-cyclohexanetetraol via three key steps, namely, deoxygenation, inversion of a hydroxyl group, and N-methylation. The physical and biological properties of synthetic 3-O-demethylsporaricin A and an authentic sample derived from sporaricin B were identical.