Monosaccharides chemical shifts

Hricovini, M., Malkina, O. L., Bizik, F., Nagy, L. T., Malkin, V. G., 1997, Calculation of NMR Chemical Shifts and Spin-Spin Coupling Constants in the Monosaccharide Methyl [1 ]) xylopyTniiosidc Using a Density Functional Theory Approach , J. Phys. Chem. A, 101, 9756. 

Identification of constitutive monosaccharides two-dimensional homonuclear NMR techniques such as DQF-COSY and TOCSY are used to assign chemical-shift values for all C-bonded protons in each individual monosaccharide (96). One-dimensional NMR spectra provide useful information about the chemical shifts and scalar couplings of such well-resolved signals as methyl groups for 6-deoxy monosaccharides (fucose, quinovose, and rhamnose) at 6 1.1-1.3 ppm. 

Fig. 1 also may be used to note some general characteristics of C spectra of carbohydrate polymers ( -11) Chemical shifts of anomeric carbons (C-l), in the region of 100-110 p.p.m., are typically well separated from other signals. As compared with C-l of the related monosaccharides (12-15)j the anomeric carbon is strongly deshielded (commonly by 7-10 p.p.m.) through glycoside formation (9)> i.e., by the change from 0-H to an 0-C bond. 

Rotamers Top — chemical shift values of major rotamer. The parts in bold indicate the monosaccharide involved. 

Table 5.17. 13C Chemical Shifts (c>c in ppm) of Selected Monosaccharide Derivatives. 

Introduction to 2-D NMR experiments The purpose of the standard 1-D H NMR experiment is to achieve structure-related information about sample protons (i.e., chemical shifts, spin-spin couplings, and integration data) describing the relative number of protons. Applied to anthocyanins, this information may help to identify the aglycone (anthocyanidin), number of monosaccharides present, and anomeric configuration of the monosaccharides. However, for most anthocyanins, the information gained by a standard 1 -D H NMR experiment is insufficient for complete structure elucidation. In recent years, various 2-D NMR experiments have evolved as the most powerful tools for complete structure elucidation of anthocyanins. 

Chemical shifts (8) are given in p.p.m. downfield from sodium 4,4-dimethyl-4-silapentane-l-sulfonate the values in parentheses are coupling constants (Jia) in Hz. The numbering of the monosaccharide units in the reference compounds corresponds to that in the asialoglycan-Asn (see fundamental structure in Table II). Values from a convolution-difference spectrum. 

Influence of oe-(2— 3)-linked and -(2— 6)-linked, Terminal N-Acetylneuraminic Acid Residues on the Chemical Shift of Anomeric and N-Acetyl Protons of Other Monosaccharide Residues Present in a Dianteunary Clycari 4 1 ... 

H NMR Chemical Shifts for Monosaccharide Residues from the Carbohydrate-Protein Linkage-Region of Proteoglycans... 

The application of 13C-n.m.r. spectroscopy to carbohydrates has already been reviewed many times,4-11 and has been discussed in two monographs.I2-13 In each of those reviews, limited numbers of chemical-shift data for carbohydrates were given. As, for identification purposes, it is useful to have convenient access to an extensive list of chemical-shift data, the main purpose of the present article is to provide an almost complete collection of 13C-n.m.r. chemical-shifts of monosaccharides, their methyl glycosides, and acetates see Tables I-V. In addition, examples of shift data for as many different types of monosaccharide derivative as possible will be given see Tables VI-XXI. Nucleosides and nucleotides are not included, but data on compounds of these types have been reported, for example in Refs. 8, 12, and 14. 

The most important, practical application of 13C-n.m.r. spectroscopy is probably the simple characterization and identification of organic compounds. Because of the simplicity of proton-decoupled carbon spectra, and the sensitivity of carbon-13 chemical-shifts towards structural changes, carbon spectra are extremely well suited for this purpose (see, for example, Ref. 84), and it is for this reason that the emphasis of the present article has been placed on presenting chemical-shift data of monosaccharides and their derivatives. Such data are also important for structural studies of oligo- and poly-saccharides,3 and for the investigation of such mixtures as those arising from mutarotation85-87 (see Section 11,4) or from other reactions.34... 

Carbon-13 chemical-shifts have been used to study the interaction of monosaccharides with such complexing agents as borates124,125 and calcium ions.126,127 Paramagnetic complexing-agents are mentioned in Section III,5. 

Experience has indicated that the chemical shifts of the monosaccharides are similar to those of the monosaccharide residues within the polysaccharide, except for substituent effects.37,38 These effects, caused by the attachment of any substituent to a sugar moiety, cause an increase in the chemical shift of the carbon atom directly involved in the linkage this increase is usually accompanied by a decrease of smaller magnitude (or, sometimes, an increase) in the chemical shifts... 

H Chemical Shifts" of Structural-reporter Groups of Constituent Monosaccharides, and of Amino Acid Protons for Glyco-asparagines... 

H Chemical Shifts of Structural- reporter Croups of Constituent Monosaccharides for Asialo-agalacto Di-, and Asialo Di-, Tri-, Tri -, and Tetra-antennary Oligosaccharides (Compounds 6, 7, and 10-12)... 

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