Fructose triacetate

In 1952, Wolfrom and Hilton demonstrated that L-sorbose was also capable of forming dimeric dianhydrides,22 and they postulated sorbofuranosyl and pyra-nosyl cationic intermediates. In 1955, Boggs and Smith23 postulated a fructofu-ranosyl cationic intermediate in the formation of per-O-acetyl ot-D-Fru/-1,2 2,l -p-D-Fru/[di-D-fructose anhydride I (5)] from inulin triacetate. They indicated that three adjacent P-2,l -linked fructofuranosyl units would be required for formation of the dianhydride. 

Ohle118 obtained 1-methyl-D-fructose by methylating 2,3 4,5-diiso-propylidene-D-fructopyranose and then hydrolyzing the resulting crystalline 1-methyl derivative. Brigl and Widmaier m have prepared 1-methyl-D-fructose from dibenzylidene-D-fructose. An alternative method is described by Brauns and Frush142 who hydrolyzed crystalline 1-methyl-D-fructosyl fluoride 3,4,5-triacetate, obtained by methylation with methyl iodide-silver oxide of crystalline D-fructosyl fluoride 3,4,5-triacetate, which results from the action of anhydrous hydrogen fluoride on D-fructose 1,3,4,5-tetraacetate. 

Although Pacsu regarded these substances as (3)-monoacetyl-/3-methylfructoside 2,6) with orthoester structure and its triacetate (IXb), their true structure has not yet been rigidly determined. The alternate structures of 3,4,5-triacetyl-n-fructose methyl 1,2-orthoacetate (IXa) and D-fructose methyl 1,2-orthoacetate are still to be considered. 

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... 

Di-O-methyl-D-glucose and thence the corresponding dimethyl-D-fruc-tose was produced from l,2-0-isopropylidene-6-0-triphenylmethyl-a-D-glucofuranose and purified by way of its a-1,2,6-triacetate, catalytic treatment of which, with sodium methoxide, gave the 6-acetate. Reaction with a stronger solution of this reagent afforded the fructose dimethyl ether. 1,6-Anhydro-... 

The structure of the second di-O-isopropyl idene-D-fructose has been defined (181). It is known that carbon 1 in this isomer is open since, on oxidation with alkaline permanganate, an acid was obtained, without acetone removal, which on acid hydrolysis yielded 1-C-carboxy-D-arabinose (2-keto-D-gluconic acid) (182). Acid hydrolysis yielded a mono-O-isopropylidene-D-fructose characterized as a crystalline triacetate. Deacetylation of this nonreducing compound yielded a product consuming one mole of periodate per mole of substance. Only two possible nonreducing mono-O-isopropyli-dene derivatives are compatible with this analysis 1,2-0-isopropylidene-D-fructofuranose and 2,3-0-isopropylidene-D-fructopyranose. The former is eliminated by the formation of a carboxyl group at carbon 1. Since hydrolysis by aqueous acid will not shift the position of an attached isopropylidene group, the structure of this mono-O-isopropylidene-D-fructose is therefore established as 2,3-0-isopropylidene-D-fructopyranose and the second diiso-propylidene derivative is established as 2,3 4,5-di-0-isopropylidene-D-fructose (II). 

The phenylphosphinyl D-fructopyranose 4-ether (1) has been prepared from D-fructose, and the analogue (2) of L-fucose has also been reported The same group has also prepared the "P in the ring" glucose derivatives (3) and (4), as well as 2,4-dideoxy-4-methoxyphosphinyl-D-ery Aro-pentofuranose triacetate/... 

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