Monosaccharide derivatives

With 2,3-[isopropylidenebis(oxy)]propanal the facial selectivity of the allylstannane generated from tin(II) chloride, the disodium salt of diethyl 2,3-dihydroxybutanoatc, and 3-bromo-1-propene (see preceding section) is overwhelmed by the facial selectivity of the substrate97. Some selectivity was observed in coupling monosaccharide derived allylstannanes with monosaccharide aldehydes99. 

This section relates to the introduction of a double or triple bond between two contiguous carbon atoms of the backbone chain of a monosaccharide derivative. A double bond between a carbon atom of the backbone chain and an atom outside that chain, or a double or triple bond between two carbon atoms outside the backbone chain, will be treated according to the normal rules of organic nomenclature [13,14],... 

Note 1. The term glycal is a non-preferred, trivial name for cyclic enol ether derivatives of sugars having a double bond between carbon atoms 1 and 2 of the ring. It should not be used or modified as a class name for monosaccharide derivatives having a double bond in any other position. 

Monosaccharide derivatives having a triple bond or cumulative double bonds in the backbone chain are named by the methods of 2-Carb-17.2, with the infix n-yn for a triple bond and infixes such as ij-dien for cumulative double bonds. 

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 first observations on the stereochemical dependence of spin-lattice relaxation-rates of carbohydrate molecules, beginning in " 1972, provided a general survey of the nonselective relaxation-rates of the anomeric protons of monosaccharide derivatives, oligosaccharides, and some polysaccharides. 

The most well known and most widely used compounds mentioned in the chapter are the doubly protected monosaccharide derivatives (cf. Schemes 16-18 and 27-29), which serve as building blocks for the regio- and stereospecific synthesis of a host of more complex carbohydrates. A number of newly discovered alkaloids contain fused 5 6 6-triheterocyclic systems these compounds may come from not only traditional (plant) sources, for example, compounds 96, 292-294, 446, and 447, but also insects (compounds 531-533), marine animals of various kinds, for example, sponges (compounds 58 R = H or OH) and ascidians (compound 289), and amphibians (compound 535). Although the majority of these alkaloids are known to be toxic in sufficient quantity, any possible therapeutic applications have apparently not yet been disclosed. 

By treatment of chitin with alkali the acetyl groups can be removed and a polyglucosamine formed. This compound, chitosan, appears to be broken down with nitrous acid even under mild conditions, the sole product being a monosaccharide derivative. 

Scheme 25. Monosaccharide derivatives containing protecting groups whose cleavage can be achieved by Montmorillonite K-10 in aqueous methanol.

Scheme 31. Monosaccharide derivatives obtained by oxidation at secondary hydroxyl groups using PCC in the presence of 3A or 4A MS.

Reaction of nitromethane and monosaccharide-derived dialdehydes is a useful tool that has been broadly used for the preparation of nitro and amino sugars, and carbocycles.30 Dialdehydes can easily be obtained by oxidative cleavage of conveniently protected monosaccharides with sodium periodate. Their subsequent Henry reaction with a nitroalkene, commonly nitromethane, usually gives isomeric mixtures that require the isolation of the major isomer.31 Thus, treatment of the D-ribose derivative 27 with sodium periodate gave dialdehyde 28, which was subjected to a Henry reaction with nitromethane, to afford nitrosugar 29 as an epimeric mixture (Scheme 11).32... 

In such cases, it is practical to apply the following considerations. The analysis usually provides data that can be expressed as numbers of moles of each monosaccharide derivative per mole of sample. The expression [NS] - [DS] - 2 [TS] - 3 [TeS] (where NS = nonsubsti-tuted (terminal), DS = disubstituted (branched), TS = trisubstituted, and TeS = tetrasubstituted sugars) should theoretically give a value of unity. If values far below unity are encountered, several sources of analytical error must be considered. Undermethylation must be considered, as well as erroneously low values for terminal sugars caused by the volatility of their methylated derivatives. Nonglycosidic substituents, such as sulfate,56 phosphate, and acetal groups must also be considered.48... 

Van Boom and co-workers published an expeditious route to chiral oxepines with monosaccharide derivatives as precursors. The synthesis was accomplished by treatment of 210 with alkoxyallenes 8 under Rutjes s optimized reaction conditions (Scheme 8.50) [121]. 

B. Reaction of LiAIH4 with Monosaccharides and Diols 1. Monosaccharide Derivatives... 

In 1966 Landor and co-workers reported the preparation of chiral derivatives of LAH by its reaction with monosaccharide derivatives (46,61). These studies have been reviewed by Inch (62). Landor and co-workers planned to construct... 

Dimethylthiocarbamates are known to undergo photochemical cleavage, leading, in the case of monosaccharide derivatives, to deoxy sugars and to free alcohols (see Scheme 12). ... 

Vicinal proton-carbon coupling constants in a series of conformationally rigid monosaccharide derivatives showed a satisfactory dependence of upon the torsion angles (2). The... 

Chemical Class Sulfamate-substituted monosaccharide derivative... 

The structures of two (p-bromophenyl)hydrazones have been determined from projection data. The first was that of D-ribose,112 in which the D-ribose is acyclic, in a sickle18 conformation, and C-l, C-2, C-3, and C-4 are coplanar. Rotation of C-5 out of this plane relieves the 0-2, 0-4 interaction that would be present in the extended conformation and brings 0-5 close to 0-2, so that an intramolecular hydrogen-bond can be formed this is the first (and, thus far, the only) case of an intramolecular hydrogen bond in a crystal of a monosaccharide derivative. The hydroxyl groups on C-2, C-3, and C-4 form three intermolecular hydrogen-bonds. 

Considerable effort has heen directed towards the synthesis of monosaccharide derivatives, and, in particular, C-glycosyl compounds, from Diels-Alder adducts offuran. Just and his group investigated the reaction of furan with a number of dienophiles, and described many interesting transformations of the adducts obtained from... 

A fundamentally different approach to the total synthesis of monosaccharide derivatives from 417, based on the telomerization principle, was elaborated by Kunieda and coworkers.278,277 These authors... 

For simple, linear polymers such as amylose, the positions of the glycosidic bonds are determined by treating the intact polysaccharide with methyl iodide in a strongly basic medium to convert all free hydroxyls to acid-stable methyl ethers, then hydrolyzing the methylated polysaccharide in acid. The only free hydroxyls present in the monosaccharide derivatives so produced are those that were involved in glycosidic bonds. To de-... 

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