SYNTHESIS OF 6′-SUBSTITUTED MALTOSES

Derivatives of maltose substituted at position 6′ have been prepared by the replacement of a 6′-O-p-toluenesulfonate ester by various reagents. Tritylation of 1,6-anhydro-β-maltose followed by acetylation and detritylation yielded 2,3,2′,3′,4′-penta-O-acetyl-1,6-anhydro-β-maltose, which gave the 6′-O-p-toluenesulfonate in good yield. Replacement of the sulfonate ester with iodide led to a derivative from which 6′-deoxy-maltose was prepared by reduction, acetolysis, and deacetylation. 6′-Deoxy-6′-mercapto-maltose was prepared by replacement of the sulfonate with thiolacetate followed by acetolysis and deacetylation. 6′-Amino-6′-deoxy-maltose was prepared in low yield by azide replacement of the sulfonate, deacetylation, reduction, and mild acid hydrolysis.Attempts to prepare 6-substituted derivatives from benzyl 4′,6'-O-benzylidene-β-maltoside were unsuccessful. The possible explanations for the unreactivity of position 6 are discussed.