Carbohydrates derivatives and

Multifunctional carbohydrate derivatives have been used widely as chiral synthons [240], and they have more recently found application as chiral auxiliaries [241], In this chapter, examples of carbohydrates in which an alcohol functional group is the point of attachment to the reagent wall be presented. Alkylations of ester etiolates of the D-allofiiranose derivative 1.47 or of the diacetoneghicose 

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Trivial Names for Carbohydrates and Derivatives with their Systematic Equivalents and Symbols (non-limiting list)... 

Vinke, H., 1991, Oxidation of Carbohydrates and Derivatives using Carbon Supported Noble Metal Catalysts , Ph.D. Thesis, TU Delft, The Netherlands. 

Aldolases catalyze asymmetric aldol reactions via either Schiff base formation (type I aldolase) or activation by Zn2+ (type II aldolase) (Figure 1.16). The most common natural donors of aldoalses are dihydroxyacetone phosphate (DHAP), pyruvate/phosphoenolpyruvate (PEP), acetaldehyde and glycine (Figure 1.17) [71], When acetaldehyde is used as the donor, 2-deoxyribose-5-phosphate aldolases (DERAs) are able to catalyze a sequential aldol reaction to form 2,4-didexoyhexoses [72,73]. Aldolases have been used to synthesize a variety of carbohydrates and derivatives, such as azasugars, cyclitols and densely functionalized chiral linear or cyclic molecules [74,75]. 

Synthesis of Carbohydrates and Derivatives from 7-Oxanorbornenes ( Naked Sugars )... 

In summary, for aU of the above-mentioned applications, the synthesis of carbohydrates and derivatives thereof is necessary to foster the field of glyco-engineering. Many procedures have been established to produce synthetic (neo)glycoconjugates by chemical or enzymatic methods and these are summarized in excellent reviews [12, 27, 28]. 

Glycosides are formed by higher plants from a variety of externally applied substances, regardless of whether or not the substance is toxic or growth active. The herbicidal chemicals have been discussed in other Sections, and this Section will deal with glycoside formation of some other compounds, and with some carbohydrates and derivatives that have shown growth activity. 

The use of nonpolar chemically bonded stationary phases with a polar mobile phase is referred to as reverse-phase HPLC. This technique separates sample components according to hydrophobicity. It is widely used for the separation of all types of biomolecules, including peptides, nucleotides, carbohydrates, and derivatives of amino acids. Typical solvent systems are water-methanol, water-acetonitrile, and water-tetrahydrofiiran mixtures. Figure 3.15 shows the results of protein separation on a silica-based reverse-phase column. 

The fundamental work of Lemieux and coworkers21 introduced the successful application of H-n.m.r. spectroscopy to structural problems in the carbohydrate field. Since then, numerous studies have been devoted to the (partial) determination of primary structures of carbohydrates and derivatives thereof, as well as to the elucidation of their conformation in solution, by means of H-n.m.r. spectroscopy. An exhaustive discussion of all these contributions is beyond the scope of this article. For comprehensive reviews, see Refs. 22-28. 

DHAP (A) is used in nature as a C3-methylene component for the efficient and stereoselective formation of carbohydrates (Scheme 1). In this pathway DHAP reacts with D-glyceraldehyde-3-phosphate (1) via an enzyme-catalyzed aldol reaction to form 2. After dephosphonyla-tion the aldol adduct 3 is then transformed to various carbohydrates and derivatives (Calvin 1962). 

Typical organic components in representative, mature biomass species are shown in Table 3.9 along with the corresponding ash contents. With few exceptions, the order of abundance of the major organic components in whole-plant samples of terrestrial biomass is celluloses, hemicelluloses, lignins, and proteins. Aquatic biomass does not appear to follow this trend. The cellulosic components are often much lower in concentration than the hemicelluloses as illustrated by the data for water hyacinth. Other carbohydrates and derivatives are dominant in species such as giant brown kelp to almost complete exclusion of the celluloses. The hemicelluloses and lignins have not been found in this species. 

Hen and turkey egg-white lysozyme, thaumatin. carbohydrates and derivatives, alcohols, amino acids and... 

For many purposes, these oxidants are interchangeable however, the fact that periodate functions best in water, and lead tetraacetate in organic solvents, makes glycol-cleavage oxidation possible with all types of carbohydrates and derivatives. For favorable examples, the behavior of the two reagents toward a given compound is sufficiently different to provide complementary information. 

Some Carbohydrates and Derivatives that Have Been Examined by GLC... 

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