Synthesis fructose dianhydrides

The raw materials from which di-D-fructose dianhydrides can be obtained in appreciable yield are readily available from comparatively inexpensive agricultural feedstocks. Thus, these compounds are attractive as chiral-starting materials for chemical synthesis. Their stability to acid and heat, and their relative rigidity, because of the conformational constraints covered here, are also features that might be exploited during syntheses.119 A series of variously substituted di-D-fructose dianhydrides has been prepared,119 starting from 6,6 -dideoxy-6,6 -di-halosucroses. The properties of these and other derivatives of di-D-fructose dianhydrides are summarized in Tables XIV-XX. Two of these derivatives, 48 and 56, exhibit thermotropic liquid-crystal properties.119... 

Paper ionophoresis, sugars, Maurice Stacey s work, 17 Pectic acid, 350, 352,414 Pectin, 348, 350-353 Pectinic acid, 353 Pentulose, synthesis, 281 D-cryt/iro-Pentulose 5-phosphate, 289 Peptidoglycans, 167-168 Per-O-acetylated di-D-fructose dianhydride derivatives... 

J. Defaye and J. M. G. Fernandez, Difructose dianhydrides as synthetic intermediates, Synthesis of 3,6-anhydro-keto-D-fructose, Tetrahedron Asymmetry, 5 (1994) 2241-2250. 

Scheme 2 Synthesis of ot-D-fructofuranose P-D-fructopyranose l,2 2,l -dianhydride (9) and a-D-fructofuranose P-D-fmctofuranose l,2 2,l -dianhydride (10) from o-fructose, sucrose and D-fmc-tose oligosaccharides by the action of pyridinium poly(hydrogenfluOTide) complex...

Scheme 5 Synthesis of D-fructose-D-glucose mixed dianhydrides from trehalulose by the action of HF-reagents...

The 0-3-0-3 distance is notably shorter in the p-D-fructofuranose p-o-fructo-pyranose l,2 2,l -dianhydride 13 than in the other three DFAs in this subset (Fig. 3). Its synthesis was accomplished by linking two o-fructopyranose moieties having different protecting group patterns with the o-xylylene bridge (40, Scheme 13). In one of those o-fructose residues pyranose furanose interconver-sion became possible after activation with TfOH ( 41). The higher reactivity of the five-membered ring towards spirocyclization led to the p,p-isomer with total selectivity in 41% yield [54]. 

The use of phenyl p-o-glucopyranoside as internal standard and authentic samples of DFAs obtained by synthesis allowed determination of the corresponding response factors for quantitative analysis. The relative abundance of DFA diaster-eomers in a D-fructose caramel obtained by heating a concentrated solution of sucrose in the presence of 10% citric acid was found to correspond to a kinetic distribution, the ot-D-fructofuranose p-o-fructofuranose l,2 2,l -dianhydride 10 being the major component in the mixture (Fig. 4). 

I. Defaye, A. Gadelle, and C. Pedersen, Acetal and ester protecting-groups in the hydr, anden fluoride-catalysed synthesis of D-fructose and L-sorbose difuranose dianhydrides, Carbohydr. Res., 174 (1988) 323-329. 

The chemisry of the hexulosyl bromide 20 has beat studied and a facile synthesis of the azidogalactosyl bromide 21 by way of D-galactal triacetate has been outlined. The conversion of 6-bromo-6-deoxyaldonolactones into 3,6-anhydro-aldonic acids is covered in Chapter 16 and the conversion of difructose dianhydride by way of deoxyhalo derivatives into 3,6-anhydro-keto-D-fructose is mentioned... 

Treatment of l-0-(a-D-glucopyranosyl)-D-fructose with hydrogen fluoride in pyridine has afforded a l,T 2,2 dianhydride mixture with the fructose moiety in either the pyranose or furanose fonn. Some novel 1,6-anhydro-lactose derivatives for the synthesis of oligosaccharides containing N-acetyl-lactosamine residues are mentioned in Chapter 4, and a 3,6-anhydroglucofuranose derivative resulting from an unusual molecular rearrangement of a xanthate is described in Chapter 7. 

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