Anhydro monosaccharides

Trivial names for anhydro monosaccharides, though established by usage, are not recommended because of possible confusion with polysaccharide names based on the use of the termination -an . 

This type of polysaccharide may be prepared from anhydro disaccharides. Polymerization reactivity of anhydro disaccharide derivatives, however, is lower than that of the corresponding anhydro monosaccharide derivatives. In order to obtain comb-shaped polysaccharides of moderate molecular weight, highly reactive disaccharide anhydrides are required. Hence we gave attention to a dideoxygenated anhydro-ring structure. 

An intramolecular ether (commonly called an intramolecular anhydride), formally arising by elimination of water from two hydroxy groups of a single molecule of a monosaccharide (aldose or ketose) or monosaccharide derivative, is named by attaching the (detachable) prefix anhydro- preceded by a pair of locants identifying the two hydroxy groups involved. 

The compounds usually known as monosaccharide anhydrides or glycose anhydrides (earlier glycosans ), formation of which involves the anomeric hydroxy group, are named by the same procedure. In these cases the order of preference of ring size designators is pyranose > furanose > septanose. However, three- or four-membered rings should normally be cited as anhydro if there is a choice. 

Similarly, anhydro derivatives of monosaccharides and disaccharides readily react with 359 to give the respective carba-di- and -tri-saccharide. 

Fourteen DFAs and some oligomers were identified in caramel obtained by thermal treatment of inufin. - Monosaccharides (glucose, fructose), dehydration products (1,6-anhydro-p-D-glucopyranose, 1,6-anhydro-p-D-glucofuranose), disaccharides (gentiobiose and isomaltose), and oligosaccharides were also found in glucose and sucrose caramel. ... 

Dermatan sulfate, also termed chondroitin sulfate B, a related glycosaminoglycan constituent of connective tissue, was known to be composed of galactosamine and a uronic acid, originally believed to be glucuronic acid but then claimed to be iduronic acid based largely on color reactions and paper chromatography. However, the d or L-enantiomer status of the latter monosaccharide was not clear. Jeanloz and Stoffyn unequivocally characterized the monosaccharide as L-iduronic acid by consecutive desulfation, reduction, and hydrolysis of the polysaccharide, followed by isolation of the crystalline 2,3,4-tri-0-acetyl-l,6-anhydro-/ -L-idopyranose, which was shown to be identical to an authentic specimen synthesized from 1,2-0-isopropylidene-/ -L-idofuranose.34... 

Tables V-LVII detail H and F shift and coupling information, and Tables LVIII to LXXI incorporate the C-n.m.r. data. The data within this compilation are arranged according to the following outline hexoses prior to pentoses, followed by anhydro sugars, sugar acids and lactones, amino sugars (and their synthetic, A -containing precursors), mono-, di-, and tri-deoxy sugars, branched derivatives, ketoses, polyfluorinated monosaccharides, and, finally, difluorinated amino sugars. Within this compilation, and even within each table, pyranoid derivatives are listed prior to their furanoid counterparts, hexoses prior to pentoses, functionalized prior to deoxy compounds the arrangement within each sub-table is made alphabetically.

C-N.m.r. Data for Difluorinated Monosaccharides, Including Anhydro and Unsaturated Derivatives... 

C-6,209,214 anhydro sugars,branched monosaccharides, fluori-nated amino sugars,difluorinated monosaccharides, and fluorinated monosaccharide phosphates,and phosphonates have been described. Further progress has been achieved in the synthesis and n.m.r.-spectral analysis of fluorinated avermectin Bu, tylono-lide, and neuraminic acid derivatives. " ... 

Monomers are all 1,6-anhydroaldohexose derivatives. Parent monosaccharides are indicated by the conventional abbreviations, and maltose by Mai. Other symbols Ac, 3-O-acetyl An, 1,6-anhydro Bzl, benzyl Bbl, p-bromobenzyl Cro, 3-0-(2-butenyl) Ip, 3,4-O-isopropylidene and Xy, p-methylbenzyl (p-xylyl). 6 10 mole-% PF . 

The first of these methods involves the reaction of triphenyl phosphite methiodide with methyl 3-0-methyl-2-0-p-tolylsulfonyl-a-D-glucopyrano-side, hydrogenation of the resulting 4,6-diiodo derivative, and hydrolysis,186 as adapted to monosaccharides by Kochetkov and coworkers.1,0 In another approach,281 ethyl 2,3-anhydro-4,6-dideoxy-D-nbo-hexopyranoside, obtained from desosamine, was treated with sodium methoxide, to give a mixture of 2- and 3-methyl ethers. After fractionation and separation of side products,288 the 3-methyl ether was hydrolyzed, to give crystalline chalcose. McNally and Overend800 have described another synthesis, starting from methyl 4-deoxy-D-xj/Zo-hexoside.107... 

Spirocyclic derivatives 118 of pyranoses were prepared in moderate yields by tethering the succinimide on C-6 of the protected monosaccharide skeleton [24c]. The photochemical behavior of 1,6-anhydro sugars 119 [78e], 121 [78f), and 123 [78e] that bear the succinimide moiety in 2-, 3-, and... 

SCHEME 1. Action of a-(l 4)-glucan lyase on floridean starch (the monosaccharide derivatives, which are split from the nonreducing ends of the polysaccharide chains probably in the form of 2-hydroxyglucal, are tautomerized to the more stable 1,5-anhydro-D-fructose, 5). 

One trf the most popular methods of synthesizing anhydro derivative of monosaccharide containing a-oxide rings is the alkaline saponification sugar tosylates (5). We have studied the possibility of... 

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