Carbohydrates heterocyclics

Functional Groups aldehydes ketones alcohols alkyl groups and rings carboxylic and phosphoric acids and esters amines carboxylic acids amides carbohydrate heterocyclic bases phosphate esters... 

The term half-space concisely represents the region in space, either above or below a flat molecular moiety. Stereotopic or paired half-spaces are separated by a surface that may or may not be planar. The alternative term molecular face is more descriptive of a given molecular structure. Two stereotopic molecular faces are separated by a surface that is assumed to coincide with the plane of a finite, flat molecular framework. We use molecular face, in preference to half-space, as it is intimately linked to the term facioselectivity. Ring systems in carbohydrates, heterocyclic bases, steroids, porphyrins (see refs. 129(a), 129(b) above) are also said to have molecular faces, albeit in a generalized sense. 

This book is designed to be suitable for students and researchers. It is highly recommended as a reference book and for teaching the fascinating topics related to carbohydrates, heterocycles and organic synthesis. In addition to its importance in academia, it is also an excellent source for information about the variety of methods used in the synthesis of heterocycles important to industry. 

THIO-CLICK AND DOMINO APPROACH TO CARBOHYDRATE HETEROCYCLES... 

Mahrwald and coworkers [14] reported a new synthetic approach to carbohydrate heterocycles via three-component reactions starting from unprotected maltose, L-proline, and ethyl isocyanoacetate. The process is catalyzed by N,N-diisopropylethylamine (Huning s base) and produces glycopeptide mimetic as functionalized lactone, which was isolated in a 36% yield as syn/anti mixture 83/17. The methodology is depicted in Scheme 6.10. 

SCHEME 6.10 Mahrwald s synthesis of carbohydrate heterocycles starting from maltose, L-proline, and ethyl isocyanoacetate. 

Witczak, Z. J. Thio-click and domino reaction tandem approach to carbohydrate heterocycles, abstracts of 248th ACS National Meeting, August 12-17, 2014, San Francisco, CA, Abstract CARB-23. 

Nucleic acids are acidic substances present m the nuclei of cells and were known long before anyone suspected they were the primary substances involved m the storage transmission and processing of genetic information There are two kinds of nucleic acids ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) Both are complicated biopolymers based on three structural units a carbohydrate a phosphate ester linkage between carbohydrates and a heterocyclic aromatic compound The heterocyclic aro matic compounds are referred to as purine and pyrimidine bases We 11 begin with them and follow the structural thread... 

Pyranose form (Section 25 7) Six membered ring ansing via cyclic hemiacetal formation between the carbonyl group and a hydroxyl group of a carbohydrate Pyrimidine (Section 28 1) The heterocyclic aromatic com pound... 

Application of NMR spectroscopy to heterocyclic chemistry has developed very rapidly during the past 15 years, and the technique is now used almost as routinely as H NMR spectroscopy. There are four main areas of application of interest to the heterocyclic chemist (i) elucidation of structure, where the method can be particularly valuable for complex natural products such as alkaloids and carbohydrate antibiotics (ii) stereochemical studies, especially conformational analysis of saturated heterocyclic systems (iii) the correlation of various theoretical aspects of structure and electronic distribution with chemical shifts, coupling constants and other NMR derived parameters and (iv) the unravelling of biosynthetic pathways to natural products, where, in contrast to related studies with " C-labelled precursors, stepwise degradation of the secondary metabolite is usually unnecessary. 

Many classes of natural product possess heterocyclic components (e.g. alkaloids, carbohydrates). However, their structures are often complex, and although structure-based names derived by using the principles outlined in the foregoing sections can be devised, such names tend to be impossibly cumbersome. Furthermore, the properties of complex natural product structures are often closely bound up with their stereochemistry, and for a molecule containing a number of asymmetric elements the specification of a particular stereoisomer by using the fundamental descriptors (R/S, EjZ) is a job few chemists relish. 

Asymmetric syntheses of heterocycles using carbohydrates as chiral auxiliaries 97T14823. 

Carbohydrate mimetics including heterocyclic fragments and a new strategy for tackling the problem of biological recognition with participation of carbohydrates 99AG(E)2300. 

Because sugars are involved in most of the mechanisms established for the synthesis of these heterocycles, the development of carbohydrate chemistry has been most helpful in these researches—especially for the preparation of specifically labeled molecules. Conversely, the contribution of these efforts to carbohydrate chemistry and biochemistry has shown the involvement in biosynthesis of 1 -deoxy-D-f/rreo-pentulose—scarcely before recognized and considered a rare sugar—and of fully functionalized pentuloses of still unknown configuration (or their phosphates). Finally, evidence has been found in prokaryotes for a most extraordinary transformation of 5-amino-l-(P-D-ribofuranosyl)imidazole 5 -phos-phate into a pyrimidine. Surely, this transformation should be explained in terms... 

This series in heterocychc chemistry is being introduced to collectively make available critically and comprehensively reviewed hterature scattered in various journals as papers and review articles. All sorts of heterocyclic compounds originating from synthesis, natural products, marine products, insects, etc. will be covered. Several heterocyclic compounds play a significant role in maintaining life. Blood constituents hemoglobin and purines, as well as pyrimidines, are constituents of nucleic acid (DNA and RNA). Several amino acids, carbohydrates, vitamins, alkaloids, antibiotics, etc. are also heterocyclic compounds that are essential for life. Heterocyclic compounds are widely used in clinical practice as drugs, but all applications of heterocyclic medicines can not be discussed in detail. In addition to such applications, heterocyclic compounds also find several applications in the plastics industry, in photography as sensitizers and developers, and the in dye industry as dyes, etc. 

Comprehensive Organic Chemistry , Pergamon, Elmsford, NY, 1979, is a six-volume treatise on the synthesis and reactions of organic compounds. The first three volumes cover the various functional groups, vol. 4, heterocyclic compounds, and vol. 5, biological compounds such as proteins, carbohydrates, and lipids. Probably the most useful volume is vol. 6, which contains formula, subject, and author indexes, as well as indexes of reactions and... 

BIOORGANIC MEDICINAL CHEMISTRY BIOORGANIC MEDICINAL CHEMISTRY LETTERS CARBOHYDRATE RESEARCH HETEROCYCLES (distributed by Elsevier) TETRAHEDRON TETRAHEDRON ASYMMETRY TETRAHEDRON LETTERS... 

The results obtained by Garcia Gonzalez and his coworkers attracted interest abroad, and it was a source of great satisfaction for him to receive, in 1953, an invitation from Professor M. L. Wolfrom to write the first of his articles in this Series. A further international recognition as a carbohydrate chemist ensued in 1965, when he was invited to serve as a member of the Editorial Advisory Board of the new international journal Carbohydrate Research. In 1975, he was asked to contribute with a lecture, subsequently published, on Synthesis of Polyhydroxyalkyl Heterocycles, to a Symposium on New Synthetic Methods for Carbohydrates organized by the American Chemical Society to commemorate the 100th anniversary of the Society (New York, 1976). 

Arya DP (2006) Diazo and Diazonium DNA Cleavage Agents Studies on Model Systems and Natural Product Mechanisms of Action. 2 129-152 El Ashry ESH, El KUany Y, Nahas NM (2007) Manipulation of Carbohydrate Carbon Atoms for the Synthesis of Heterocycles. 7 1-30 El Ashry ESH, see El Nemr A (2007) 7 249-285... 

Ferndndez-Bolanos JG, Lopez 6 (2007) Heterocycles from Carbohydrate Isothiocyanates. 7 67-100... 

The preparation of nucleosides by reaction between carbohydrates and heterocyclic bases is fundamental to the study of the important biological activity... 

Aqueous aza-Diels-Alder reactions of chiral aldehydes, prepared from carbohydrates and with benzylamine hydrochloride and cyclopentadiene, were promoted by lanthanide triflates (Eq. 12.65).137 The nitrogen-containing heterocyclic products were further transformed into aza sugars, which are potential inhibitors against glycoprocessing enzymes. 

Nitroalkenes with Chiral Auxiliaries The use of carbohydrates as chiral auxiliary in Diels-Alder reactions for the stereoselective preparation of carbocyclic and heterocyclic chiral rings is well documented.48 For example, D-manno-nitroalkene reacts with 2,3-dimethyl-1,3-butadiene to give a 65 35 mixture of adducts, as shown in Eq. 8.29. The configurations at C-4 and C-5 have been determined to be (4R,5R) and (45,55), respectively. Hydrolysis of the product followed by degradative oxidation of the sugar side chains leads to enantiomerically... 

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