Conformational studies on pertrimethylsilyl derivatives of some mono- and disaccharides by 220 MHz PMR spectroscopy

Streefkerk, Dirk G.; Bie, M. J. A. De; Vliegenthart, Johannes F.G.

doi:10.1016/0040-4020(73)80026-2

Cited by 70 publications

(22 citation statements)

References 30 publications

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“…With different parametrizations of the Karplus equation the following ratios were obtained gg:gt:tg=60:40:0 (Gerlt and Youngblood, 1980), gg:gt:tg=71:34:-5 (Streefkerk et al, 1973) and gg:gt:tg=63:52:-15 (Haasnoot et al, 1980). The gg:gt:tg ratio calculated according to Gerlt and Youngblood is closest to the theoretical data obtained above from the MMC simulations.…”

Section: Discussionsupporting

confidence: 58%

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Conformational analysis of ?-d-Fuc-(1?4)-?-d-GlcNAc-OMe. One-dimensional transient NOE experiments and metropolis Monte Carlo simulations

1993

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One-dimensional transient NOE build-up curves were measured for the synthetic disaccharide alpha-D-Fuc-(1-->4)-beta-D-GlcNAc 1 utilizing Gaussian shaped pulses. Simulated build-up curves from Metropolis Monte Carlo simulations were compared to the experimental data. Disaccharide 1 is structurally related to methyl beta-D-maltoside in that it also contains an alpha-(1-->4) linkage, and it has the same configuration of groups around the glycosidic linkage. Analysis of NOEs in methyl beta-D-maltoside is restricted to those observed upon selective excitation of H1' because of severe spectral overlap. The situation is different in 1 where 1H-NMR signals are well separated. Several interglycosidic NOEs were observed. The corresponding build-up curves allowed an accurate determination of the conformational preferences at the glycosidic linkage in 1. Comparison of experimental and theoretical NOE build-up curves showed clearly that rigid minimum-energy models cannot account for the experimental data. The best fit of experimental NOE build-up curves was obtained with theoretical curves from a 2 x 10(6) step Metropolis Monte Carlo simulation with the temperature parameter set at 1000 K. Finally, it was observed that only the interglycosidic NOE H5'/H6-pro-S significantly depends upon varying conformation distributions at the alpha-(1-->4)-glycosidic linkage, induced by choosing different temperature parameters for the Metropolis Monte Carlo simulations.

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Section: Discussionsupporting

confidence: 58%

“…Experimental vicinal homonuclear coupling constants J5.6 were used to calculate the populations of gt, gg and tg rotamers in 1 using the Karplus equation as parametrized by Haasnoot et al (1980), by Streefkerk et al (1973) and by Gerlt and Youngblood (1980).…”

Section: Introductionmentioning

confidence: 99%

Conformational analysis of ?-d-Fuc-(1?4)-?-d-GlcNAc-OMe. One-dimensional transient NOE experiments and metropolis Monte Carlo simulations

1993

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“…The structural elucidation of the reaction products proceeded as follows: a series of simulations was carried out for various and characteristic 3 J(HH) coupling constant values in pyranose rings (Table 1), 43,44) using two high J(HH) values (7.9, 10.4 Hz; aa/aa), two small J(HH) values (3.4, 0.9 Hz; ae/ae), and high and small J(HH) values (10.4, 3.4 Hz; aa/ae). * To whom correspondence should be addressed.…”

Section: Resultsmentioning

confidence: 99%

“…Accurate knowledge of these coupling constants is not necessary to achieve computed simulations since these couplings are relatively constant throughout the hexopyranose series. 43,44) Profiles were recorded for the polarization delay tϭ0.0357 s value, which is maximum for tϭ1/4 2 J(CH). Superposition of all INEPT polarization curves displays characteristic D values, allowing spectral editing capability (Fig.…”

Section: Resultsmentioning

confidence: 99%

Structural Analysis of Partially Acetylated Glycosides by Refocused-Decoupled Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) Experiments: A Qualitative and Quantitative Method

Pouységu

Jeso

Lartigue³

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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Selective acetylation-deacetylation methodologies are very commonly used in carbohydrate chemistry to generate a suitable protective-group strategy for hydroxyl functions. 1,2) Their effectiveness in the preparation of partially acetylated monosaccharides has received particular attention, owing to their great potential usefulness as precursors in the synthesis of oligosaccharides, 3) in the preparation of O-substituted derivatives, 4) as chiral building blocks in organic synthesis, 5) and as reference model compounds for the analysis of polysaccharides. 6) Many enzymatic and chemical methods have been reported for the preparation of partially acetylated derivatives. As a rule, chemical transformations have the disadvantage that multiple synthetic steps are generally needed, with usually modest overall yields. [7][8][9][10][11][12][13][14] In contrast to chemical techniques, enzymic catalysis is conceivably a one-stage process in regioselective acylation [15][16][17][18][19][20][21] and deacylation [22][23][24][25] as well as in chemoselective deprotection. 26,27) Since the advent of enzymatic methods, numerous investigations have focused on the enzymatically catalyzed regioselective hydrolysis of peracetylated mono-and disaccharide model compounds to account for the nature and behaviour of both the enzyme and the substrate. [28][29][30][31] However, whatever the chosen strategy the question arises concerning the location of acetyl groups, which proved to be labile under basic conditions and prone to intramolecular migrations mainly during the purification steps. 32,33) Subsequent careful separation of the reaction products is needed to assign the deacetylated generated compounds unambiguously. Apart from some solvent change techniques 34) and selective deuteriation methods, 35,36) assignment of acetyl groups is inferred from diagnostic variations in 13 C chemical shifts of the ring carbon atoms with substituent effects. These empirical and experimental methods have given rise to a flood of 13 C-NMR data in carbohydrate chemistry. 37,38) Obviously, the plurality of these factors makes the measurements time-consuming. From a practical point of view, it appears attractive to avoid the isolation and purification steps and also to preclude the prerequisite tedious steps of assigning 1 H-or 13 C-NMR resonances by the usual combination of 1 H-1 H homonuclear and 1 H-13 C heteronuclear 2D correlation experiments.To solve such restrictive analytical problems, we recently applied the refocused-decoupled insensitive nuclei enhanced by polarization transfer (INEPT) pulse sequence to the structural analysis of acetylated carbohydrate model compounds. 39) By taking advantage of computed graphic representations of the refocused INEPT analytical relation, 40) we demonstrated that individual resonances can be assigned unambiguously to their specific positions in the pyranose ring, thanks to the exploitation of certain characteristic refocusing delay times D, closely linked to the spatial proton environment around the different ...

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“…The energies of the free molecules should be compared with gas-phase data, but as these are not available it will be most proper to compare them with data from solutions. From NMR studies of a-D-glucose in acetone a ratio of 77:23 for gg:gt conformations was found (Streefkerk, de Bie & Vliegenthart, 1973), corresponding to an energy difference of 3.3 kJ mol -~ at room temperature, obviously much smaller than the calculated HE free __g of 13.0 kJ mol-k…”

Section: Conformation Of the Hydroxymethyl Groupmentioning

confidence: 99%

Influence of hydrogen bonds on molecular conformation. Molecular-mechanics calculations on α-D-glucose

Kroon-Batenburg¹,

Kanters²

1983

Acta Crystallogr Sect B

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To study the effect of the crystal environment on the molecular conformation of saccharides a model is developed in which the surroundings of a single molecule are represented by a limited number of water molecules. This model is tested on the molecular conformation of a-D-glucose in two different crystal modifications, that of a-D-glucose and of a-D-glucose monohydrate. The molecular-mechanics force field MM2 is used to cover intramolecular interactions and a previously described hydrogen-bond potential for intermolecular hydrogen-bond interactions. The results are most pronounced for the conformation of hydroxyl groups; r.m.s, deviations of 16.4 and 17.2 ° for the isolated molecules diminish to 4.8 and 6.7 ° for the water-surrounded model of a-D-glucose and ~t-Oglucose monohydrate respectively. Energetical considerations are given for the conformation of the hydroxymethyl group.

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Conformational studies on pertrimethylsilyl derivatives of some mono- and disaccharides by 220 MHz PMR spectroscopy

Cited by 70 publications

References 30 publications

Conformational analysis of ?-d-Fuc-(1?4)-?-d-GlcNAc-OMe. One-dimensional transient NOE experiments and metropolis Monte Carlo simulations

Conformational analysis of ?-d-Fuc-(1?4)-?-d-GlcNAc-OMe. One-dimensional transient NOE experiments and metropolis Monte Carlo simulations

Structural Analysis of Partially Acetylated Glycosides by Refocused-Decoupled Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) Experiments: A Qualitative and Quantitative Method

Influence of hydrogen bonds on molecular conformation. Molecular-mechanics calculations on α-D-glucose

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