Carbohydrate Chemistry provides review coverage of all publications relevant to the chemistry of monosaccharides and oligosaccharides in a given year. The amount of research in this field appearing in the organic chemical literature is increasing because of the enhanced importance of the subject, especially in areas of medicinal chemistry and biology. In no part of the field is this more apparent than in the synthesis of oligosaccharides required by scientists working in glycobiology. Clycomedicinal chemistry and its reliance on carbohydrate synthesis is now very well established, for example, by the preparation of specific carbohydrate- based antigens, especially cancer-specific oligosaccharides and glycoconjugates. Coverage of topics such as nucleosides, amino-sugars, alditols and cyclitols also covers much research of relevance to biological and medicinal chemistry. Each volume of the series brings together references to all published work in given areas of the subject and serves as a comprehensive database for the active research chemist Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.
Carbohydrate Chemistry Volume 22
Monosaccharides, Disaccharides, and Specific Oligosaccharides
By R. J. FerrierThe Royal Society of Chemistry
Copyright © 1990 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-0-85186-212-5Contents
Chapter 1 Introduction and General Aspects, 1,
Chapter 2 Free Sugars, 3,
Chapter 3 Glycosides and Disaccharides, 15,
Chapter 4 Oligosaccharides, 46,
Chapter 5 Ethers and Anhydro-sugars, 56,
Chapter 6 Acetal, 65,
Chapter 7 Esters, 71,
Chapter 8 Halogeno-sugars, 86,
Chapter 9 Amino-sugars, 91,
Chapter 10 Miscellaneous Nitrogen Derivatives, 108,
Chapter 11 Thio-and Seleno-sugars, 120,
Chapter 12 Deoxy-sugars, 126,
Chapter 13 Unsaturated Derivatives, 136,
Chapter 14 Branched-chain Sugars, 145,
Chapter 15 Aldosuloses, Dialdoses, and Diuloses, 156,
Chapter 16 Sugar Acids and Lactones, 159,
Chapter 17 Inorganic Derivatives, 170,
Chapter 18 Alditols and Cyclitols, 177,
Chapter 19 Antibiotics, 192,
Chapter 20 Nucleosides, 205,
Chapter 21 N.M.R. Spectroscopy and Conformational Features, 228,
Chapter 22 Other Physical Methods, 237,
Chapter 23 Separatory and Analytical Methods, 248,
Chapter 24 Synthesis of Enantiomerically Pure Noncarbohydrate Compounds, 258,
Author Index, 271,
CHAPTER 1
Introduction and General Aspects
The field continues to develop on all fronts, and improvements in synthetic methodology are giving access to substantially more complex products. Nowhere is this move apparent than in oligosaccharide and C-glycoside synthesis and in the use of synthetic procedures which are dependent on carbohydrate-derived carbanions and particularly free radicals. The increasing interest shown by "non-carbohydrate chemists" in carbohydrate chemistry is welcomed; their contributions have enlivened the field appreciably as is best illustrated by their descriptions of novel approaches to glycoside synthesis and, of course, many syntheses of enantiomerically pure non-carbohydrates from sugars.
El Khadem has published a book "Carbohydrate Chemistry: Monosaccharides and their Oligomers", and reviews of general interest have appeared on the chemistry and biochemistry of the sweetness of sugars and on the use of immobilised enzymes in preparative carbohydrate chemistry.
Volume 45 of Advances in Carbohydrate Chemistry and Biochemistry (1987) contains articles on circular dichroism n.m.r. (proton relaxation rate data in structural analysis) and mass spectrometry (FAB methodology). The volume also contains tributes to the lives and work of Professors B. Helferich and F. C. Gonzalez.
The succeeding volume of the series contains reviews on H.p.l.c. of carbohydrates, n.m.r. of fluorinated monosaccharides," the use of photosensitive protecting groups in carbohydrate synthesis'' and high-temperature transformations of monosaccharides in aqueous solution.
Appreciations of the lives and work of Professor K. Onedera and V. Deulofeu are also included in this volume.
CHAPTER 2
Free Sugars
1 Theoretical Aspects
Recent progress in the physical chemistry of small carbohydrate compounds has been reviewed. There is accumulating evidence that solvation plays an important part in determining the solution equilibria and conformational properties of sugars. The standard geometries of both anomers of the eight hexopyranoses in the 4C1 conformation have been calculated and are given in the form of orthogonal co-ordinates. The geometries found for pyranose rings corresponded to the averaged ring structures determined from X-ray diffraction analyses of 161 compounds (see B. Sheldrick and D. Akrigg, Acta Crystallogr., 1980, 836. 1615). A revised CHARMM molecular mechanics potential-energy function has been developed for use in the dynamical simulation of simple carbohydrates in aqueous solution. Application to the molecular dynamics simulation of the motions of α-D-glucopyranose in vacuo in both the 4C1 and 1C4 conformation produced a D-glucose molecule less flexible then had previously been determined. CNDO Force constants for both anomers of D-glucopyranose have been evaluated, and an ab initio investigation of the electronic structure of the α-D-glucose molecule by use of the Hartree-Fock-Roothan method has been carried out. The effective charges agreed with those derived from semi-empirical calculations.
The hydrophobic indices, i.e, the ratios of hydrophobic to hydrophilic surface areas, of seven monosaccharides have been determined. They were found to correlate well with the partition coefficients of the polystyrene-water system for monosaccharides. The concept of hydrophobic indices is important in the consideration of the hydrophobic interactions of flat molecules in aqueous solution. In an effort to establish quantitative structure-activity relationships for carbohydrates, an experimental data-matrix containing the Rf values of sixteen monosaccharides in thirteen solvent systems was subjected to principal component analysis (PCA). Four PC's (t1-t4) were found to explain 97.8% of the variance, and the first of these (t1), which described 90% of the variance, was tentatively interpreted as a hydrophobicity scale. Ab initio Calculations have shown that D-ribose is energetically stabilised relative to its L-enantiomer by parity-violating weak interaction (see Vol. 20, p. 2, ref. 4). The possible significance of these findings with regard to evolution has been pointed out.
2 Synthesis
A review on the synthesis of complex carbohydrates by a combination of chemical and enzymic methods has been published. A new strategy for the predictable creation of new chiral centres and its application to the synthesis of sugars and macrocycles is presented in a review on the use of double asymmetric induction in the aldol condensation, the Diels Alder cycloaddition, epoxidation and hydrogenation. Two approaches to the construction of appropriately functionalised six-carbon chains are outlined in a review on the dg novo synthesis of carbohydrates from achiral precursors: (i), hetero-Diels Alder reaction with inverse electron demand of functionalised 1-oxa-1, 3-dienes with dienophiles such as enol ethers followed by diastereoselective addition to the new double bond and (ii), Sharpless oxidation of racemic or meso-divinyl glycols, with concomitant kinetic resolution.
Sugars with four, six, and eight carbon atoms were formed from glycolaldehyde in an aqueous suspension of sodium montmorilIonite at 40°C, hexoses being the main products (see Vol. 20, p. 3, ref. 8). The conversion efficiency was 90% and an aldol-type mechanism has been suggested for the reaction. Aldoses are smoothly decarbonylated by chlorotris(triphenyl)rhodium in N-methylpyrrolidin-2-one at 130°C to give the next lower alditols. D-Glucose for example gives D-arabinose and 2-deoxv-D-erYthro-pentose gives 1-deoxyerythritol in 90% yield. Ketoses undergo more complex dehydration-decarbonylation reactions; thus furfuraldehyde was formed in 79% yield from fructose. Experiments with [1-13C]-labelled substrate showed that C-1 was lost during the reaction.
2.1 Pentoses. – On reaction with aqueous Pb(OH)2 3,4-Q-isopropylidene-L-arabinose rearranged to 2-deoxy-L-ribono-1, 4-lactone which was reduced to 2-deoxy-L-erythro-pentofuranose by sodium borohydride. 2,4-Q-Benzylidene-L-xylose has been prepared in high yield by periodate oxidation of 2,4-O-benzylidene-D-glucitol. Iron(III)trifluoroacetate proved to be an efficient catalyst in...
