Conformational analysis. XVII. 2-Alkoxy- and 2-alkylthiotetrahydropyrans and 2-alkoxy-1,3-dioxanes. Anomeric effect

Eliel, Ernest L.; Giza, Chester A.

doi:10.1021/jo01274a015

Cited by 164 publications

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“…l(c) clearly describe for each of the two glucopyranosyl-O(1) groups the A1 conformer (de Hoog, et al, 1969;Eliel, 1969), which is favored by the anomeric effect and which has often been found (Eliel & Giza, 1968) in crystalline pyranosides. Specifically, the torsion angles 74.8 and 61.7 ° describe gauche or +syn-clinal (Klyne & Prelog, 1960) conformations, and the angles -165 and -177 ° describe trans or anti-periplanar conformations.…”

Section: Discussionmentioning

confidence: 99%

The crystal structure of α,α-trehalose dihydrate from three independent X-ray determinations

Brown¹,

Rohrer²,

Berking³

et al. 1972

Acta Crystallogr B Struct Crystallogr Cryst Chem

148

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The structure of the dihydrate of the nonreducing disaccharide a,a-trehalose (a-D-glucopyranosyl a-D-glucopyranoside) has been determined independently by direct methods in three different laboratories. There are four units C~2H22Ol~.2H20 in an orthorhombic cell (P212a2a) with a= 12"230 (2), Comparison of coordinates suggests that their standard errors may have been underestimated by a factor of ~2. The a,a-trehalose molecule has approximate C2 symmetry, but there are some significant structural differences between the two chemically equivalent halves. The angles at the ring oxygen atoms are 114-0 and 114-2°; the angle at the glycosidic oxygen is 115.8 °. The two rings have Cl conformations; the conformations about the linking C-O bonds are stabilized by the conformational 6anomeric effect' and also by a complex system of hydrogen bonds involving all of the hydroxyl groups, both water molecules, and one ring oxygen. By hydrogen bonding each glucopyranosy] moiety is linked to the other in the same molecule indirectly through two different water molecules. The helical arrangement of hydrogen bonds about the screw axes parallel to e suggests the possibility of observing ferroelectric behavior.

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Section: Discussionmentioning

confidence: 99%

The crystal structure of α,α-trehalose dihydrate from three independent X-ray determinations

Brown¹,

Rohrer²,

Berking³

et al. 1972

Acta Crystallogr B Struct Crystallogr Cryst Chem

148

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“…31,32 The relative stability of the anomers is a function of the electrostatic environment; in vapor phase and nonpolar solvents, α-glucose is preferred, with the population shifting toward β-glucose as the polarity of the solvent increases. 31,33 As noted above, β-glucose is preferred in aqueous solution. Because the glucose−water interaction has been wellstudied, with only a sampling of the relevant literature cited here, this work only reports properties of neat glucose to the extent that it allows us to contrast our results with inorganic salt using consistent methodology.…”

Section: ■ Introductionmentioning

confidence: 92%

Sodium Ion Interactions with Aqueous Glucose: Insights from Quantum Mechanics, Molecular Dynamics, and Experiment

Mayes

Tian

Nolte³

et al. 2013

J. Phys. Chem. B

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In the last several decades, significant efforts have been conducted to understand the fundamental reactivity of glucose derived from plant biomass in various chemical environments for conversion to renewable fuels and chemicals. For reactions of glucose in water, it is known that inorganic salts naturally present in biomass alter the product distribution in various deconstruction processes. However, the molecular-level interactions of alkali metal ions and glucose are unknown. These interactions are of physiological interest as well, for example, as they relate to cation-glucose cotransport. Here, we employ quantum mechanics (QM) to understand the interaction of a prevalent alkali metal, sodium, with glucose from a structural and thermodynamic perspective. The effect on B-glucose is subtle: a sodium ion perturbs bond lengths and atomic partial charges less than rotating a hydroxymethyl group. In contrast, the presence of a sodium ion significantly perturbs the partial charges of Î±-glucose anomeric and ring oxygens. Molecular dynamics (MD) simulations provide dynamic sampling in explicit water, and both the QM and the MD results show that sodium ions associate at many positions with respect to glucose with reasonably equivalent propensity. This promiscuous binding nature of Na + suggests that computational studies of glucose reactions in the presence of inorganic salts need to ensure thorough sampling of the cation positions, in addition to sampling glucose rotamers. The effect of NaCl on the relative populations of the anomers is experimentally quantified with light polarimetry. These results support the computational findings that Na + interacts similarly with a-and B-glucose. ABSTRACT: In the last several decades, significant efforts have been conducted to understand the fundamental reactivity of glucose derived from plant biomass in various chemical environments for conversion to renewable fuels and chemicals. For reactions of glucose in water, it is known that inorganic salts naturally present in biomass alter the product distribution in various deconstruction processes. However, the molecular-level interactions of alkali metal ions and glucose are unknown. These interactions are of physiological interest as well, for example, as they relate to cation-glucose cotransport. Here, we employ quantum mechanics (QM) to understand the interaction of a prevalent alkali metal, sodium, with glucose from a structural and thermodynamic perspective. The effect on β-glucose is subtle: a sodium ion perturbs bond lengths and atomic partial charges less than rotating a hydroxymethyl group. In contrast, the presence of a sodium ion significantly perturbs the partial charges of α-glucose anomeric and ring oxygens. Molecular dynamics (MD) simulations provide dynamic sampling in explicit water, and both the QM and the MD results show that sodium ions associate at many positions with respect to glucose with reasonably equivalent propensity. This promiscuous binding nature of Na + suggests that computational studies of g...

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“…51t is well known that the anomeric effect decreases with increasing polarity of the solvent (27,(33)(34)(35)(36) conformational equilibria studied by 'H nrnr were highly biased (axial preference of 98-99%) and were estimated by an approximate method of analysis so that the small influence of the substituent on the phenyl ring could not be detected.…”

Section: -Aryloxytetrahydropyransmentioning

confidence: 99%

The conformational behaviour of 2-aryloxytetrahydropyrans and 2-acetoxytetrahydropyran, and barrier to ring inversion

Ouedraogo¹,

Lessard²

1991

Can. J. Chem.

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CHFCl? solvents show that the axial preference increases with electron withdrawal in the aryloxy group: from 79% (AGoE +A = -0.4 kcal mol-I) (4-OCH,) to 90% (AGoE+A = -0.7 kcal mol-I) (4-NO2) in CF2Br2. The axial preference (anomeric effect) is smaller in the more polar CHFC12 solvent, as expected, and the substituent effect is smaller also: change in AGoE+A from -0.3 (4-OCH,) to -0.5 (4-NO2) kcal mol-I. However, the axial preference of 2-acetoxytetrahydropyran is shown to be smaller than that of 2-phenoxytetrahydropyran in CF2Br2 solvent although the acetoxy group is expected to be more electronegative than the phenoxy group. Furthermore, the polarity of the solvent has no effect on the conformational equilibrium of 2-acetoxytetrahydropyran. The results are interpreted in terms of both orbital and electrostatic interactions. The ring-inversion barrier of 2-alkoxy and 2-aryloxytetrahydropyrans, determined by the temperature-coalescence method, is lower than that of tetrahydropyran by about 1.5 kcal rnol-I .Key words: 2-substituted tetrahydropyrans, conformational analysis, anomeric effect, ring inversion.ADAMA OUEDRAOGO et JEAN LESSARD. Can. J. Chem. 69.474 (1991).Les donntes de la resonance magnktique nuclCaire du I3C a 156 K, dans les solvants CF2Br2 et CHFCl,, montrent que la prCfCrence axiale d'une serie de tetrahydropyranes portant, en position 2, un groupement phCnoxy substitut a la position par0 croit avec le pouvoir Clectroattracteur du substituant : de 79% (AGOE-,~ = -0.4 kcal mol-') pour un groupement 0CH3 a 90% (AGoE +A = -0.7 kcal mol-I) pour un groupement nitro dans CF2Br2. La prCfCrence axiale (l'effet anomere) est moindre dans CHFCl?, solvant plus polaire, tel qu'attendu, et l'effet de substituant est tgalement plus faible : variation de AGoE + A de -0.3 (OCH,) a -0.5 (NO2) kcal mol-I. Toutefois, dans CF2Br,, la proportion de conformere axial est moins ClevCe pour le 2-acCtoxytCtrahydropyrane que pour le 2-phtnoxytetrahydropyrane m&me si le groupement acCtoxy est plus Clectrontgatif que le groupement phCnoxy. De plus, la polarit6 du solvant n'a pas d'influence sur l'tquilibre conformationnel du 2-acCtoxytttrahydropyrane. Les rCsultats sont interprttCs en termes d'interactions orbitalaires et Clectrostatiques. La dktermination de la barriere d'inversion de cycle d'alcoxy-et d'aryloxytCtrahydropyranes par la mCthode de coalescence de tempkrature montre que la barritre est plus faible que celle du tttrahydropyrane d'environ 1,5 kcal par mole.Mots elks : tCtrahydropyranes substituts en position 2, analyse conformationnelle, effet anomere, inversion de cycle.

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Conformational analysis. XVII. 2-Alkoxy- and 2-alkylthiotetrahydropyrans and 2-alkoxy-1,3-dioxanes. Anomeric effect

Cited by 164 publications

References 0 publications

The crystal structure of α,α-trehalose dihydrate from three independent X-ray determinations

The crystal structure of α,α-trehalose dihydrate from three independent X-ray determinations

Sodium Ion Interactions with Aqueous Glucose: Insights from Quantum Mechanics, Molecular Dynamics, and Experiment

The conformational behaviour of 2-aryloxytetrahydropyrans and 2-acetoxytetrahydropyran, and barrier to ring inversion

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