Sugars structure diversity

The study of the structure of the sugars in solution can be approached chemically if the chemistry used is as sensitive to sugar structure as sugars are diverse in their structure. The boric acid-sugar reaction could serve this purpose if some of the fundamental aspects of this reaction were understood. Priority should probably be given to (1) the determination of the structure of the borate-sugar complex, (2) the evaluation of the stability constants for these complexes, and (3) the determination of the mechanism of the reaction. 

The saccharides represent a structurally diverse group of compounds, which are often derivatised with a variety of functional groups. The chemical modification of saccharides often involves the installation of a functional group that at an appropriate time can be converted into another functionality. In this chapter, synthetic methodologies for the preparation of halogenated, unsaturated and deoxygenated sugar derivatives will be discussed and furthermore methods for the introduction of amino, sulfate and phosphate moieties will be covered. 

Bitter taste is elicited by structurally diverse compounds, including phenols, ions, amino acids and peptides, alkaloids, acylated sugars, glycosides, nitrogenous compounds, and thiocarbamates. Taste receptor cells are primarily associated with papillae on the tongue. The signal transduction mechanisms by which taste perception occurs are well not understood, but are the focus of intensive research as reviewed recently (6). 

These compounds illustrate the structural diversity of carbohydrates. Glucose is the most common simple sugar, whereas cellulose, which comprises wood, piant stems, and grass, is the most common carbohydrate in the piant world. Doxorubicin, an anticancer drug that has a carbohydrate ring as part of its structure, has been used in the treatment of ieukemia, Hodgkin s disease, and cancers of the breast, biadder, and ovaries. 2 -Deoxyadenosine 5 -monophosphate is one of the four nucieotides that form DNA. 

There are many instances in which the introduction of amines with specific substitution patterns is desired. With the abundance of structurally diverse commercially available amines from which to choose, the use of these compounds as nucleophiles is extremely valuable. While the example illustrated in Scheme 6.29 focuses on the hydrazine displacement of a secondary tosylate from a furanose sugar derivative [56], this type of reaction is easily achieved with most primary and secondary amines. Where the introduction of direct NH2 groups is desired, the best methods rely on the reduction of azides or nitro groups, or the hydrolysis (hydrazinolysis) of imides [32]. 

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