Ring-closing double reductive amination route to aza-heteroannulated sugars

1,4-Dicarbonyl derivatives of glycosides are produced by ozonolysis or Wacker oxidation. A stable ozonide is isolated and a carbonyl group reduced whilst maintaining the ozonide functionality. The 1,4-dicarbonyl compounds are converted to various N-substituted pyrrolidines by diastereoselective double reductive amination. The resulting aza-heteroannulated sugars showed no significant inhibition of any glycosidase.