Anhydrohexopyranose and 1,6-Anhydrohexofuranose Analogs

The methylsulfonium salt of l,6-anhydro-l(6)-thio-/3-D-glucopyra-nose (240) is apparently an intermediate in the solvolysis of methyl l-thio-6-O-p-tolylsulfonyl-/3-D-glucopyranoside, which involves methyl migration, and results in 6-S-methyl-6-thio-D-glucose.779 

A distant, sulfur analog of l,6-anhydro-2,3,4-trideoxy-j3-D-glt/cero-hexopyranose (26) is (lR,5R)-6,8-dioxa-3-thiabicyclo[3.2.1]octane (241), which was prepared by periodic acid oxidation of levoglucosan (6), followed by reduction of the resulting dialdehyde 100 to diol 242, and by p-toluenesulfonylation to 243, and replacement of the two sulfonic ester groups of 243 with sodium hydrogensulfide.731 

The preparation7793-779 and hydrogenolysis779d of racemic 3,6,8-tri-oxabicyclo[3.2.1]octane and its methyl derivatives have also been described. 

In acid solutions, such anhydrides, like the corresponding amino hexoses, are dehydrated to give derivatives of pyridine. The imino 

Even 6,1-lactones of hexuronic acids,785,786 for example, 2,3,4-tri-O-acetyl-jS-D-glucopyranurono-6,1-lactone785 (254) and the corresponding 2,3,4-tri-0-(2,2,2-trichloroethoxycarbonyl) ester,787 may be considered to be 1,6-anhydrohexose analogs however, they behave as ordinary lactones. 

---