Fructofuranose

There are millions of organic compounds many consist of highly intricate molecules, so their names can be very complicated. You could, for example, find yourself asking for ct-D-glucopyranosyl(l—>2)-(3-D-fructofuranose when all you wanted was sucrose (sugar). However, for most of this text, we will need to know only a few simple organic compounds, and this section will introduce some of them. Chapters 18 and 19 present a more complete introduction to the nomenclature of organic compounds. 

Thus the trans relationship between the hydroxymethyl group and the C-l hydroxy group in a-D-glucopyranose, and the cis relationship between the methyl group and the C-l hydroxy group in P-L-fucopyranose, are clearly shown. Note that representation of ketoses may require a different modification of the Fischer projection, as shown in the fructofuranose example above. Here C-2 is rotated about the bond with C-3 to accommodate the long bond to C-2 from the oxygen at C-5. 

If a sugar is esterified with two or more phosphate groups, the compound is termed bisphosphate, trisphosphate etc. (e.g. fructofuranose 1,6-bisphosphate). The term diphosphate denotes an ester with diphosphoric acid, e.g. adenosine S -diphosphate. 

D-Fructofuranose 1,6-bisphosphate (often shortened to fructose 1,6-bisphosphate) or 1,6-di-O-phosphonato-D-fructofuranose or 1,6-bisphospho-D-fructofuranose... 

In 1933, Schlubach and Knoop32 isolated a di-D-fructose dianhydride from Jerusalem artichoke and tentatively identified it as difructose anhydride I [a-D-Fru/-1,2 2,1 - 3-D-Fn / (5)]. Alliuminoside ( -D-fructofuranose- -D-fructofura-nose 2,6 6,2 -dianhydride) was isolated from tubers of Allium sewertzowi by Strepkov33 in 1958. Uchiyama34 has demonstrated the enzymic formation of a-D-Fru/-1,2 2,3 -(3-D-Fru/ [di-D-fructose anhydride III (6)] from inulin by a homogenate of the roots of Lycoris radiata Herbert. 

Thermal activation of sucrose and inulin in the presence of citric acid,93 and sucrose in the presence of acetic94 acid, yields caramels containing, among other products, di-D-fructose dianhydrides and glycosylated difructose dianhydrides, as described in Section V.6). Similarly, the thermal treatment of 6-0-ot-D-glu-copyranosyl-D-fructofuranose (palatinose) in the presence of citric acid87 has been shown to produce appreciable proportions of glucosylated di-D-fructose dianhydrides. 

P-D-fructofuranose a-D-glucopyranose 1,2 2,1 -dianhydride a-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructopyranose a-D-glucopyranose 1,1 2.2 -dianhydride P-D-fructofuranose a-D-glucopyranose 2,1 3,2 -dianhydride P-D-fructopyranose a-D-sorbopyranose 1,2 2,1 -dianhydride P-D-fructopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di-a-L-sorbofuranose 1,2 2,3 -dianhydride a-l-sorbofuranose a-L-sorbopyranose 2,1 3,2 -dianhydride di-a-L-sorbopyranose 1,2 2,1 -dianhydride a-D-sorbopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbopyranose p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose a-L-sorbopyranose l,2 2,l -dianhydride P-L-sorbofuranose a-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose P-L-sorbofuranose l,2 2,l -dianhydride... 

O-a-D-Galactopyranosyl-a-D-fructofuranose 4-O-a-D-galactopyranosyl-p-D-fructopyranose 1,2 2,1 -dianhydride (31) 3-O-a-D-Glucopyranosyl-QL-D-fructofuranose 3-O-a-D-glucopyranosyl-p-D-fructopyranose 1,2 2,1 -dianhydride (32)... 

Deoxy-6-iodo-a-D-fructofuranose p-D-fructopyranose 1,2 2,1 -dianhydride (49) 6-Chloro-6-deoxy-a-D-fructofuranose p-D-fructopyranose 1,2 2,1 -dianhydride (50) 6-5-Heptyl-6-thio-tt-D-fructofuranose p-D-fructopyranose 1,2 2,l -dianhydride (51) 6-Azido-6-deoxy-a-D-ffuctofuranose P-D-fructopyranose 1,2 2,l -dianhydride (52) 6-Anuno-6-deoxy-a-D-fructofuranose p-D-fructopyranose 1,2 2,l -dianhydride (53) 6-Acetamido-6-deoxy-a-D-fructofuranose p-D-fructopyranose 1,2 2,l -dianhydride (54)... 

Anhydro-a-D-fructofuranose 6-deoxy-6-iodo-p-D-fructofuranose 1,2 2,l -dianhydride (63)... 

Deoxy-6-iodo-p-D-fructofuranose 6-deoxy-6-iodo-p-D-fructofuranose 1,2 2,3 -dianhydride (69) 6-Chloro-6-deoxy-P-D-fructofuranose 6-chloro-6-deoxy-p-D-ffuctofuranose 1,2 2,3 -dianhydride" (70)... 

By application of first-order, kinetic equations, B. Anderson and Degn claimed that an equilibrated (25°) aqueous solution of D-fructose contains 31.56% of jS-D-fructofuranose and 68.44% of -D-fructopyranose. N.m.r. studies, however, showed that, at equilibrium, a solution of D-fructose contains /3-D-fructopyranose, -D-fructofuranose, a-D-fructofuranose, and a trace of a-D-fructopyranose the distribution of these isomers was shown by gas-liquid chromatography to be 76,19.5, and 4%, respectively. Based on Anderson and Degn s result, Shallenberger reasoned that, as 0.68 X 1.8 = 1.22 (which approximates the reported sweetness of mutarotated D-fructose ), the furanose form(s) must possess very little sweetness. 

As has already been discussed, eclipsed, and anti, vicinal hydroxyl groups are not expected to elicit the sweet taste. Thus, Shallenberger suggested that jS-D-fructofuranose would be expected to have very little sweetness. The taste of this sugar has yet to be confirmed, but, significantly, Lindley and coworkers found that 5-thio-)8-D-fructofuranose is practically devoid of sweet taste. However, methyl )3-D-glucofuranoside (40) and some of the... 

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