Of penta-O-acetyl-D-glucose

Controlled oxidation of penta-O-acetyl-D-glucose diethyldithioacetal gave the mono-sulphoxide (28) which, on treatment with sodium methoxide in methanol gave, after acetylation, the 2,5-anhydro-D-mannose derivative (29) which was converted into the diethyl acetal (30). Attempted nucleophilic displacements applied to the a-L-fucopyranoside triflate (31) and its -anomer with a variety of nucleophiles... 

Wolfrom and Shilling have observed that water is an extremely poor catalyst for these reactions. Thus, it was necessary to heat an 80% solution of D-fructose at 113° for 16 hours in order to produce a 0.1% yield of n-glucose (isolated as 1,2,3,4,6-penta-O-acetyl-D-glucose). This conversion may have been aided by a slight oxonium-ion catalysis, since, although the initial pH of the reaction mixture was 6.9, the final pH was 2.7. 

Elimination of acetic acid occurs readily from phenylhydrazones of acetylated aldoses. For example, the reaction between 2,3,4,5,6-penta-O-acetyl-aZde%do-D-glucose and phenylhydrazine gives the unsaturated phenylhydrazone, 3,4,5,6-tetra-O-acetyl-l, 2-dideoxy-l -phenylazo-n-ara-6mo-hex-l-enitol (137), which may also be prepared by acetylation of the acyclic phenylhydrazones of n-glucose and D-mannose, or by condensation of 2,3,4,5,6-penta-0-acetyl-aZdeA /do-D-mannose with phenylhydrazine. 2,3,4,5,6-Penta-O-acetyl-D-glucose phenylhydrazone (138) has been... 

In the area of long-chain alkyl glycosides, 2,3,4,5,6-penta-O-acetyl-D-glucose treated with trimethylsilylated alcohols in the presence of trimethylsilyl triflate has been used to give the dialkylacetals following base catalysed deacetylation. Mild acid hydrolysis then gives the... 

There have been few investigations of the reactions of polyhydroxy compounds with alkali metal alkoxides in nonaqueous media at room temperature.. Percival" reported the preparation of D-glucose-NaOEt and D-glucose NaOMe by treating d-glucose with sodium ethoxide, and penta-O-acetyl-D-glucopyranose with sodium methoxide, respectively. The adducts were dried under vacuum at 60° for 24 hours, a treatment which would make the presence of any significant proportion of alcohol of solvation unlikely. Any traces of moisture in the preparative medium preclude the formation of an aJkoxide adduct. 

The similarity of the products obtained by ammonolysis, either of acylated nitriles, or of acylated aldehydo monosaccharides having one carbon atom less than the corresponding nitriles, was verified12 by ammonolysis of 2,3,4,5,6-penta-O-acetyl-aWehydo-D-glucose (20), which afforded the same N-acetyl-a-D-glucofuranosylamine (15) as that obtained from the peracetylated heptononitrile 14. 

The introduction of the phosphonate grouping into a sugar molecule (see Section III, 3 p. 260) has been further investigated by Paulsen and coworkers.97 Thus, the phosphonate phosphorane 120a was shown to react with 2,3,4,5,6-penta-O-acetyl-a/dehydo-D-glucose, 2,3 4,5-di-0- isopropylidene - aldehydo - D - arabinose, and 2,4-0-ethylidene-a/dehi/do-D-erythrose, leading to the unsaturated phos-phonates 229, 230a, and 231, respectively, in moderate yields. 

Because of the unusual properties of acyclic forms, certain authors prefer to underline this situation. Compound 4.16 would be called 2,3,4,5,6-penta-O-acetyl-aldehydo-D-gluco-he ose or, more briefly, aWe/iyt/o-D-glucose-pentaacetate. 

Scheme 7. Formation of the same penta-O-acetyl semicarbazone from D-glucose, semi-carbazone, and penta-O-acetyl-aZde/jydo-D-glucose...

K. Bock and C. Pedersen, Conversion of penta-0-acetyl-1,2-O-isopropylidene-aWe/iyJo-D-glucose into tri-0-acetyl-2,3-dideoxy-aWe/iyJo-D-eryt/iro-hex-2-enose, Acta Chem. Scand, B28 (1974) 853-856. 

The corresponding benzothiazolines arise by the condensation of o-aminothiophenol with aldoses. D-Glucose or D-galactose yield, under various conditions, 2-(o-gluco- or D-galacto-)pentahydroxypentylbenzo-thiazoline e.g. 20). Acetylation with acetic anhydride in pyridine yields penta-O-acetyl derivatives, whereas more drastic acylation produces hexa-OA -acetates e.g. 21). These derivatives are also accessible directly from the appropriate acetylated aldohexoses. ... 

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