24-membered phosphate ring structures

In the structure of the cyclophosphate, four tetrahedra share vertices to form a closed ring motif The four-membered phosphate rings are arranged in layers parallel to the (010) face (Fig. 23). Uranium is in eightfold coordination as isolated square antiprisms that are also arranged in layers parallel to (010). The UOs polyhedra share vertices with the phosphate tetrahedra to form a framework structure. 

Fructose differs from glucose only at C-1 and C-2. When free, fructose occurs in the more stable pyranose ring form, but when combined, as in sucrose or its phosphate esters, it assumes the five-membered furanose ring structure. 

As already shown in Sect. 4.4, ribose-2,4-diphosphate is obtained in a base-catalysed condensation of glycolaldehyde phosphate in the presence of formaldehyde (Muller et al., 1990). The phosphate group in the 4 position of the sugar prevents the formation of a 5-membered furanose ring, but a 6-membered pyranose structure can be formed. 

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