Synthesis carbohydrates, overview

For an overview of topical methods in carbohydrate chemistry, readers are referred to Khan, S. H. O Neill, R. A. Modem Methods in Carbohydrate Synthesis, Harwood Academic Publishers Amsterdam, 1996. 

The purpose of this chapter is to provide an overview of the application of monosaccharides for the synthesis of novel compounds, and in particular we have focused on bioactive compounds that target protein-protein or peptide-protein interactions. We have not reviewed extensively the application of monosaccharides as scaffolds that modulate carbohydrate-protein interactions (glycomimetics or inhibitors of glycoprocessing enzymes) as these are considered elsewhere. Also it has not been possible to detail all of the work of those groups who have contributed to this area. The review is divided into two main sections synthesis and application of monosaccharides that are SAAs and synthesis and application of monosaccharides that are not SAAs. The structures and applications of the monosaccharide building blocks are considered as are the synthesis and properties of target compounds. 

Paulsen, H. Twenty five years of carbohydrate chemistry an overview of oligosaccharide synthesis. Frontiers in Natural Product Research 1996, 1, 1-19. 

The use of isolated enzymes to form or cleave P-O bonds is an important application of biocatalysts. Restriction endonucleases, (deoxy)ribonucleases, DNA/ RNA-ligases, DNA-RNA-polymerases, reverse transcriptases etc. are central to modern molecular biology(1). Enzyme catalyzed phosphoryl transfer reactions have also found important applications in synthetic organic chemistry. In particular, the development of convenient cofactor regeneration systems has made possible the practical scale synthesis of carbohydrates, nucleoside phosphates, nucleoside phosphate sugars and other natural products and their analogs. This chapter gives an overview of this field of research. 

In this brief overview, we ve seen that oxygen and carbohydrates are produced during photosynthesis, whereas they are consumed during aerobic oxidation. In both processes, the flow of electrons creates a electrochemical gradient, or proton-motive force, that can power ATP synthesis. As we examine these two processes at the molecular level, focusing first on aerobic oxidation and then on photosynthesis, the striking parallels between them will become evident. 

In this article we provide a broad overview of the application of radical methods in carbohydrate chemistry, including typical examples classified by the type of bond formed. The factors controlling the stereoselectivity of inter- and intramolecular C-C bond formation are now well understood and have been exploited in the synthesis of C-glycosides [2]. Intramolecular C C bond formation using carbohydrate-based chiral templates also provides a powerful route to branched-chain sugars [3] and carbocycles [4]. Finally, we include synthetically useful processes involving key carbon-heteroatom and C-H bond formation. 

Hanessian, S. Glycoside synthesis based on the remote activation concept an overview. In Preparative Carbohydrate Chemistry. Hanessian, S. (ed.) Marcel Dekker New York, 1997, pp. 381-388. 

Starch is the major carbohydrate reserve in higher plants and has been a material of choice since the early days of human technology. Recently starch gained new importance as a raw material in the production of plastics, in particular, for the synthesis of monomers to produce polymers such as polydactic acid) and, after chemical modification (e.g. esterification) and thermomechanical processing, to produce thermoplastic starch. This chapter gives a general overview of the most recent research on the development of materials from starch, focusing on thermoplastic starch and the perspectives for future development in this field. A brief review on reactive extrusion of thermoplastic starch is also provided. 

Herein an overview of the most relevant approaches for the synthesis of un-natiual heterocycles of biological and industrial potential from carbohydrates is presented the natiual heterocycles have been previously reviewed [6]. This review is hmited to heterocycles with one or more of their carbon skeletons derived from carbohydrate precursors—those formed by cycloaddition reactions are not included. Also, carbohydrates with strained ring systems, oxiranes, aziridines, and thiiranes have aheady been reviewed and are not included herein [20]. The synthetic approaches for the reviewed heterocycles are divided according to the size of the heterocychc rings and the number of hetero atoms in the ring. The bicyclic ring systems are included under the smaller ring of their skeleton. 

The interaction of artificial metal ions/complexes with peptides/proteins [11], nucleic acids/DNA [12,13], enzymes [14], steroids [15] and carbohydrates [16] forms a bridge between natural and artificial macromolecular metal complexes. Biometal-organie chemistry concentrates on such complexes [17]. The reason for the increasing interest in this field lies in medical applications of metal complexes (cancer, photodynamic therapy of cancer, immunoassays, fluorescence markers, enantioselective catalysis, template orientated synthesis of peptides, etc.). Figure 2-4 presents an overview of metals in medicine [18]. Some examples are given below. 

Evidently, enzyme catalysis is thus most attractive for the synthesis and modification of biologically relevant classes of organic compounds that are typically complex, multifunctional, and vater soluble. Typical examples are those structurally related to amino acids [16, 17] or carbohydrates [18-24], vhich are difficult to prepare and handle by conventional methods of chemical synthesis. Because of the multitude of factors that might be critical to the success of an enzymatic conversion, and because of the empirical nature of their development, it is mandatory in the design of new biocatalytic processes to become familiar vith the scope and limitations of synthetically useful enzymes, both as a source of inspiration and for reference. Thus, this overview attempts to outline the current status of development for the most important aldolase biocatalysts and their preparative potential for asymmet-... 

Chapter 13, by Narayanaswamy and coworkers, provides a general overview of the potential applications of ring expansion and rearrangement reactions in the synthesis of highly valuable, septanoses as bioactive, carbohydrate-based ligands with multiple biomedical applications. 

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