On the magnitudes and origins of the “anomeric effects”, “exo-anomeric effects”, “reverse anomeric effects”, and CX and CY bond -lengths in XCH2YH molecules

Wolfe, Saul; Myung-Hwan, Whangbo; Mitchell, David J.

doi:10.1016/s0008-6215(00)85747-x

Cited by 163 publications

(21 citation statements)

References 57 publications

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“…The latter connection may be of particular interest to experimentalists, because qualitative molecular orbital arguments that deal with the structures of reactive intermediates such as 2-4 and the reactive intermediates of the present work are well developed (41), and are becoming more common as the concepts of charge transfer and stabilizing orbital interactions become more familiar. For personal use only.…”

Section: Discussionmentioning

confidence: 94%

Stereoelectronic effects and the kinetic acidities of diastereotopic hydrogens

Wolfe¹,

Stolow²,

LaJohn³

1984

Can. J. Chem.

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A general qualitative treatment is proposed which accounts for the relative reactivities of diastereotopic hydrogens adjacent to a heteroatom in proton transfer, hydride transfer, and hydrogen atom transfer reactions. This treatment focuses on the structures of the reactive intermediates formed in such reactions, which can be predicted or understood in terms of qualitative molecular orbital arguments, and on the manner in which these intermediates will undergo readdition of H+, H-, or H.. The procedure has been tested, for the specific case of proton transfer reactions, by a direct computational approach to the energy differences between diastereomeric transition states of reactions HO-+ CH3X + H20 + -CH,X (X = sulfide, sulfoxide, sulfone, sulfonium). The computations support the qualitative treatment, and are in all cases in near quantitative agreement with the extensive experimental data concerning the diastereotopic selectivities exhibited in these systems. SAUL WOLFE, ALBERT STOLOW et LAWRENCE A. LAJOHN. Can. J. Chem. 62, 1470(1984. On propose une mCthode qualitative gCntrale qui tient compte des rtactivitts relatives des hydrogknes diastCrCotopiques adjacents i un hCtCroatome lors de rCactions de transfert de protons, d'hydrures ou d'atomes d'hydrogkne. Cette mtthode met l'accent 21 la fois sur la structure des intermidiaires rkactifs formCs au cours de telles rCactions, qui peuvent Ctre prtvus ou compris en termes d'arguments qualitatifs d'orbitales moltculaires, et sur la fa~on dont ces intermtdiaires peuvent subir une nouvelle addition de H' , H-ou He. On a vtrifit cette rnCthode, dans le cas spkcifique de rkactions de transfert de proton, par une technique de calculs directs des diffkrences d'Cnergie entre les Ctats de transition diastCrCoisornkres des reactions: HO-+ CH3X + H20 + -CH2X (X = sulfure, sulfoxyde, sulfone, sulfonium). Les calculs sont en accord avec I'approche qualitative et, dans tous les cas, ils sont aussi en accord quasi-quantitatif avec les donntes exp6rimentales extensives relatives aux sClectivitCs diastCrtotopiques observtes dans ces systkmes.[Traduit par le journal]

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Section: Discussionmentioning

confidence: 94%

Stereoelectronic effects and the kinetic acidities of diastereotopic hydrogens

Wolfe¹,

Stolow²,

LaJohn³

1984

Can. J. Chem.

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“…2,123,125,126 As the name implies, the exoanomeric effect has the same basis as the anomeric effect (also known as the endoanomeric effect). These effects have both been reviewed in detail 45,123,124 and are thought to originate from a favorable overlap of an oxygen lone electron pair (n p ) into the antibonding ( σ *) orbital of the adjacent C—O bond. A favorable n p → σ * interaction is dependent on the alignment (antiperiplanar) of the n p and σ * orbitals, which is satisfied only when the underlying atomic geometry is in a particular conformation.…”

Section: First-principles Predictions Of Oligosaccharide Conformationsmentioning

confidence: 99%

“…In part, this arises from the large number of potential conformations for each peptide linkage, giving rise to an exponential number of protein conformations. , In contrast, the conformational states of oligosaccharides have been well characterized (often from NMR studies or small-molecule crystallography) and appear to be guided by well-defined and predictable rules. Understanding these rules, as summarized in the essential reference Conformations of Carbohydrates, and the underlying physics ,− has enabled accurate force fields for carbohydrate modeling to be created. ,,− However, from a modeling perspective, the most significant property of oligosaccharides is that two-bond glycosidic linkages between pyranose rings predominantly populate only a single conformation. This can be illustrated by comparing the bond rotational energies for 2- O -methyltetrahydropyran (2-OMe-THP) in the equatorial (β-analogue) and axial (α) configuration (Figure ).…”

Section: First-principles Predictions Of Oligosaccharide Conformationsmentioning

confidence: 99%

“…In the cyclohexyl analogues, the two conformational states are determined by rotational barriers that arise principally from steric repulsions; in the THP analogues, the exoanomeric effect is present, leading to a preference only for one rotamer. ,,, As the name implies, the exoanomeric effect has the same basis as the anomeric effect (also known as the endoanomeric effect). These effects have both been reviewed in detail ,, and are thought to originate from a favorable overlap of an oxygen lone electron pair (n p ) into the antibonding (σ*) orbital of the adjacent C–O bond. A favorable n p → σ* interaction is dependent on the alignment (antiperiplanar) of the n p and σ* orbitals, which is satisfied only when the underlying atomic geometry is in a particular conformation.…”

Section: First-principles Predictions Of Oligosaccharide Conformationsmentioning

confidence: 99%

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Predicting the Structures of Glycans, Glycoproteins, and Their Complexes

2018

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Complex carbohydrates are ubiquitous in nature, and together with proteins and nucleic acids they comprise the building blocks of life. But unlike proteins and nucleic acids, carbohydrates form nonlinear polymers, and they are not characterized by robust secondary or tertiary structures but rather by distributions of well-defined conformational states. Their molecular flexibility means that oligosaccharides are often refractory to crystallization, and nuclear magnetic resonance (NMR) spectroscopy augmented by molecular dynamics (MD) simulation is the leading method for their characterization in solution. The biological importance of carbohydrate-protein interactions, in organismal development as well as in disease, places urgency on the creation of innovative experimental and theoretical methods that can predict the specificity of such interactions and quantify their strengths. Additionally, the emerging realization that protein glycosylation impacts protein function and immunogenicity places the ability to define the mechanisms by which glycosylation impacts these features at the forefront of carbohydrate modeling. This review will discuss the relevant theoretical approaches to studying the three-dimensional structures of this fascinating class of molecules and interactions, with reference to the relevant experimental data and techniques that are key for validation of the theoretical predictions.

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“…This phenomenon, which was first observed by Edward [72] and defined as anomeric effect by Lemieux [73], is partially responsible for the stereochemical outcome of processes taking place at the anomeric center of sugars [64,74,75]. What are the origins of the anomeric effect, sometimes referred to as endoanomeric effect?…”

Section: Anomeric Effectsmentioning

confidence: 99%

General Aspects of the Glycosidic Bond Formation

Demchenko

2008

Handbook of Chemical Glycosylation

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On the magnitudes and origins of the “anomeric effects”, “exo-anomeric effects”, “reverse anomeric effects”, and CX and CY bond -lengths in XCH2YH molecules

Cited by 163 publications

References 57 publications

Stereoelectronic effects and the kinetic acidities of diastereotopic hydrogens

Stereoelectronic effects and the kinetic acidities of diastereotopic hydrogens

Predicting the Structures of Glycans, Glycoproteins, and Their Complexes

General Aspects of the Glycosidic Bond Formation

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