Anhydrohexofuranose derivatives

Both the alio and manno epoxides (9) or (7), or their debenzyliden-ated analogs, undergo oxidation with methyl sulfoxide and boron trifluoride,104 but, unlike 5,6-anhydrohexofuranose derivatives (see p. 163), they do not yield a simple a-hydroxy carbonyl compound, as would be expected by analogy with simple oxiranes instead, the rearranged diulose (46) is obtained in low yield, possibly by elimination of methanol from the intermediate (47). 

Anhydrohexofuranose derivatives of the following configurations have been described gluco 78,332 manno,333 ido 79,335,337 allo,33S and galacto.153... 

Another example of a cis-fused, five-membered ring-system occurs in 3,6-anhydrohexofuranose derivatives, and 3,6-anhydro-l,2-0-isopropylidene-5-O-p-tolylsulfonyl-a-D-glucofuranose (27) contains an endo-sulfonyloxy group which can readily be displaced by sodium azide in N,N-dimethylformamide, and by hydrazine314 or sodium benzoate in 2V,2V-dimethylformamide,315 to give L-idose derivatives. 

Some analogs of 1,6-anhydrohexofuranoses have also been described. Derivatives 257 and 258 of l,6-anhydro-l(6)-thio-/3-D-gluco-furanose were respectively prepared from 255 and 256 by the action of acids.788,788 Similarly, l,6-anhydro-2,3-di-0-methyl-l(6),4-dithio-/3-D-glucofuranose (259) was obtained from the corresponding methyl glycopyranos ide. 789... 

A simple relationship exists between the structure and the optical rotation of 1,6-anhydrohexofuranoses,119,121,791 as shown in Scheme 15. [M]d values can be calculated for the 1,6-anhydrohexofuranoses121 and, presumably, also for their amino, fluoro, and deoxy derivatives by using the partial molar rotational contribution of the hydroxyl groups and of the fundamental skeleton. O.r.d. measurements in the 200-nm region seem also to be potentially valid for structural estimation.797... 

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