Heptuloses properties

The taste properties of various other ketoses, including 2-pentuloses, 2-hexuloses, and 2-octuloses, have also been studied (see Table XV) to determine the significance of the 2-hydroxyl-2-hydroxymethyl arrangement of 2-ketopyranoses. Some of these, for example, a-D-tagatose (25), -d-g/uco-2-heptulose (26), a-D-mnMno-2-heptulose (27), a-D-fa/o-2-heptulose (28), a-D-a/tro-2-heptulose (29), and D-g/ycero-a-D-g/ co-2-octulose (30),... 

An outstanding property of most heptuloses is the ease with which they form anhydrides (2,7-anhydroheptulopyranoses) under acidic conditions. The methods used for identifying these products are similar to those... 

D-Erythrose 4-phosphate has been synthesized and shown to condense with dihydroxyacetone phosphate in the presence of aldolase to give a heptulose diphosphate with properties similar to the one described above 229 ), The synthetic tetrose phosphate is optically inactive, and is decomposed by acid at a rate similar to glyceraldehyde 3-phosphate. 

An investigation of the structure of threitol, which includes n.nLr. studies, is referred to in Charter 22 (section 3.9). The (/2)-stereocheniistry at C-5 of the 7-deoxy-4-heptulose 2, obtained in an enzyme-catalysed aldol condensation (see Chapter 2) has been ascertained by extensive n.nu . experiments, especially n.O.e. studies." The stmaural properties of the alkali metal salts of D-gluconic acid in the crystalline state and in solution have been examined by F.t.i.r. and "C-n.mjr. spectroscopy."... 

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