Phosphorus-Substituted Sugar Rings

Phosphorus can be substituted for oxygen in sugar rings (phosphanyl sugars), and a number of different compounds have been prepared. Typical procedures for synthesising pyranose and furanose derivatives are illustrated in schemes (6.853, 6.854), respectively. Current methods of synthesis frequently led to mixtures of isomers. Phosphanyl sugars are not found naturally (Figure 6.20). 

The thioacetate nucleophile can displace sulfonyl esters to produce acetyl thioesters from which the acetyl group can be removed to form thio sugars. The substitution of amino, sulfhydryl, or ethyl phosphite groups at C-5 of either pentoses or hexoses results in the substitution of nitrogen, sulfur, and phosphorus atoms, respectively, for the oxygen atom in the pyranose ring. 

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