Sugar lactones

SCHEME 50. Sugar-balls obtained by direct ring-opening of sugar lactones by PAMAM-ending polyamines.387... 

Add with mixing, a 300-fold molar excess of a sugar lactone derivative, such as o-b-D-galactopyranosyl-( 1 -> 4)-D-glucono-l,5-lactone (2.6 gm) dissolved in 3 ml of DMSO. 

Formyl C-glycosides, prepared in three steps via the thiazole-based formy-lation of sugar lactones are readily condensed with hydroxylamine to give the corresponding oximes. The latter are the precursors of glycosyl nitrile oxides via the N-bromosuccinimide method (41). 

Fig. 35 Unsaturated sugar lactones obtained from monosaccharides.

Finally, when L-sorbose (81) was treated with hydrogen cyanide, a branched-chain, sugar lactone was formed which was characterized by converting it into a diacetal.127 An X-ray structure determination of this material revealed it to be 2,21 5,6-di-0-isopropylidene-[2-C-(hy-droxymethyl)-L-gulono-l,4-lactone] (82). However, all subsequent efforts to prepare 82 resulted in the formation of 2,3 5,6-di-0-isopropyli-dene-2-C-(hydroxymethyl)-L-gulono-l,4-lactone (83). 

The 7-0-silyl and 2,7-di-O-silyl derivatives (55 and 18% yields, respectively) were obtained on treatment of D-glycero-D-gulo-heplono-1,4-lactone with 1.1 eq. of rm-butylchlorodiphenylsilane (20). Sugar lactone derivatives selectively substituted with different protecting groups, which were em-... 

Ethynyl compounds react with sugar lactones to give acetylenic lactols (16,63). Reaction of 2,3-O-isopropylidene-D-ribonolactone (16a) with lithium acetylenic derivatives gave l-(2-substituted ethynyl)-2,3-0-isopropyli-dene-D-ribofuranoses. Similarly, treatment of 2,3 5,6-di-O-isopropylidene-L-gulono-1,4-lactone (9b) with various lithium acetylenic reagents gave... 

Aldonamides are readily prepared by reaction of lactones with liquid ammonia (86,99,100), with ammonium hydroxide (101,102), or by bubbling ammonia gas into alcoholic solutions of the sugar lactones (103-104). Aldonamides of the tetronic adds are stable in aqueous solution (105), but penton- or hexon-amides are hydrolyzed, as shown by the change of the optical rotation of the amide solutions (106). The hydrolysis is catalyzed by acids and bases, and the product was the ammonium salt of the aldonic acid. 

Aromatic polyamines react with sugar lactones to give heterocyclic compounds having an attached open-chain polyhydroxyalkyl substituent. Thus, treatment of aldonolactones with o-phenylenediamine afforded (117) 2-polyhydroxyalkylimidazoles (100). 

Sugar lactones react readily with hydrazine to give crystalline derivatives useful for isolation and identification (127). Thus, addition of hydrazine to a reaction mixture containing an aldonolactone facilitates isolation of the product. The lactone may be regenerated from the hydrazide by treatment with nitrous acid (128). The phenylhydrazides obtained on treatment of aldonolactones with phenylhydrazine are also useful for characterization (129,130). 

Aldonolactones are commercially available at low cost, when compared to most of the common monosaccharides. They are typically synthesized by selective anomeric oxidation of unprotected aldoses with bromine [6]. Usually the thermodynamically more stable five-membered lactone (y-lactone) predominates over the six-membered form, with the exception of o-gluconolactone, which crystallizes as the 1,5-pyranolactone (5-lactone) [7] (Scheme 1). Another method for the preparation of sugar lactones is the dehydrogenation of unprotected or partially... 

Fleet GWJ (1993) Sugar lactones as useful starting materials. In Krohn K, Kirst HA, Maas H (eds) Antibiotics and antiviral compounds chemical synthesis and modifications. VCH Verlagsgesellschaf, Weinheim, pp 333-342 Isbell HS (1963) Meth Carbohydr Chem 2 13-15... 

Scheme 2 Copolymerization of a sugar-lactone with L-lactide...

Trade Names. Sugar lactone (Treatt), Fenugreek lactone (Vioryl). 5-Ethyl-3-hydroxy-4-methyl-2(5)-furanone [698-10-2], abhexone... 

Scheme 8 Radicals from unsaturated sugar lactones.22...

Only syntheses which involve the formation of new glycosidic linkages will be considered in this article. This restriction excludes many interesting examples of copolymerization in which only one of the monomers is a carbohydrate (or carbohydrate derivative), the polymerization of carbohydrate derivatives which contain a polymerizable group4 (such as acrylate), and the polymerization of sugar lactones.1 Many of these topics have already been discussed in reviews.1-8 Also outside the scope of this article is the chemical modification of naturally occurring polysaccharides thus, we have excluded the industrially important process of dextrini-zation,10 except as it may pertain to acid condensation processes. The radiation-catalyzed polymerization and modification of carbohydrate poly-... 

TBR widely used for all sorts of hydrotreatments in petro and commodity chemicals, it is now adopted in finer chemicals. Intermediates hydrogenation includes quinones, sugars, lactones, functional aromatics, etc... Despite continuous operation, small size TBR can be adapted to batch-wise synthesis by multiple recycling of L product. Example trifluoracetic acid hydrogenation [28]. 

HI hi acetic acid allows the reduction of jS-peracetates of the higher sugar N-acetylneuraminic acid to the corresponding anomeric deoxy compounds.277 At room temperature this method gave exclusively the a-anomer, whereas at —20 °C a 4 1 a [i ratio resulted. This may be explained by thermodynamic and kinetic protonation of ester enolates generated in situ from anomeric iodide in a manner reminiscent of previous reductions of 2-iodo sugar lactones.278... 

Reaction with sugar lactones. The reaction of sugar lactones with 1 provides a preparative route to higher sugars.1 Example ... 

J. Rabiczko and M. Chmielewski, New route to bicyclic pyrazolidinones and hydroxypyrrolidinones from a,/i-unsaturated sugar lactones, J. Org. Chem., 64 (1999) 1347-1351. 

T. Okuda, S. Harigaya, and A. Kayomoyo, Studies on optical rotatory dispersion of five-member sugar-lactones configuration and signal of an optical rotatory dispersion curve, Chem. Pharm. Bull. (Tokio), 12 (1964) 504-506. 

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