SYNTHESES AND CONFORMATIONS OF 3-ACETAMIDO-3-DEOXY-5-THIO-D-XYLOSE AND 4-ACETAMIDO-4-DEOXY-5-THIO-L-LYXOSE AND SOME DERIVATIVES THEREOF

In reactions with azide ions, methyl 5-thio-3-O-p-toluenesulphonyl-alpha-D-xylopyranoside gave methyl 3-azido-3-deoxy-5-thio-alpha-D-xylopyranoside, methyl 4-O-acetyl-2,3-anhydro-5-thio-alpha-D-ribofuranoside (7) afforded a mixture of methyl 4-O-acetyl-3-azido-3-deoxy-5-thio-alpha-D-xylopyranoside and the 2-azido-2-deoxy-D-arabino analogue, and methyl 2-O-acetyl-3,4-anhydro-5-thio-alpha-D-ribopyranoside (8) afforded, after acetylation, methyl 2,4-di-O-acetyl-3-azido-3-deoxy-5-thio-alpha-D-xylopyranoside and methyl 2,3-di-O-acetyl-4-azido-4-deoxy-5-thio-beta-L-lyxopyranoside. Treatment of 7 and 8 with methanolic ammonia gave methyl 3-amino-3-deoxy-5-thio-alpha-D-Xylopyranoside and the 4-amino-3-deoxy-L-lyxo analogue, respectively, characterised as the tetra-acetates 14 and 19, respectively. Acetolysis of 14 and 19 followed by O-deacetylation gave 3-acetamido-3-deoxy-5-thio-D-xylose and 4-acetamido-4-deoxy-5-thio-L-lyxose, respectively.