The origin of the anomeric effect: conformational analysis of 2-methoxy-1,3-dimethylhexahydropyrimidine

Perrin, Charles L.; Armstrong, Kathleen B.; Fabian, Miles A.

doi:10.1021/ja00081a037

Cited by 128 publications

(91 citation statements)

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“…37b). It is commonly believed that the α anomer is more stable than the β anomer because of the stereoelectronic anomeric effect [248,249]. However, when D-glucose is dissolved in water, the α and β anomers are present in a 40:60 ratio in the 4 C 1 ring conformation (Fig.…”

Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

“…42, present the most favorable chair configuration 4 C 1 , with the largest substituent in equatorial position and the anomeric hydroxyl group in axial position (anomeric effect) [248,249]. They correlate with the corresponding G-g+/cc/g+ and G-g+/cl/gÀ of α-D-glucopyranose.…”

Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

“…The match between the experimental and calculated ab initio values of the rotational constants leads to the irrefutable identification of rotamer I as conformer cc β 2 C 5 gÀ and rotamer II as conformer cc β 2 C 5 t. Both conformers (see Fig. 45) are present in the most favorable chair configuration 2 C 5 , with the largest substituent in an equatorial position and the anomeric hydroxyl group (OH (2) ) in an axial position (anomeric effect) [248,249]. It is stabilized by a five cooperative intramolecular hydrogen bond network (Fig.…”

Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

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Microwave Spectroscopy of Biomolecular Building Blocks

Alonso

López

2014

Topics in Current Chemistry

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Microwave spectroscopy, considered as the most definitive gas phase structural probe, is able to distinguish between different conformational structures of a molecule, because they have unique spectroscopic constants and give rise to distinct individual rotational spectra.Previously, application of this technique was limited to molecular specimens possessing appreciable vapor pressures, thus discarding the possibility of studying many other molecules of biological importance, in particular those with high melting points, which had a tendency to undergo thermal reactions, and ultimately degradation, upon heating.Nowadays, the combination of laser ablation with Fourier transform microwave spectroscopy techniques, in supersonic jets, has enabled the gas-phase study of such systems. In this chapter, these techniques, including broadband spectroscopy, as well as results of their application into the study of the conformational panorama and structure of biomolecular building blocks, such as amino acids, nucleic bases, and monosaccharides, are briefly discussed, and with them, the tools for conformational assignation - rotational constants, nuclear quadrupole coupling interaction, and dipole moment.

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Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

Section: -Deoxy-d-ribose and Ribosementioning

confidence: 99%

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Microwave Spectroscopy of Biomolecular Building Blocks

Alonso

López

2014

Topics in Current Chemistry

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“…The greater stability of the ortho relative to the meta cycloadducts is due to an anomeric effect that occurs between the O1 oxygen atom of the nitronate and the O6 oxygen atom of the methyl ether, which stabilizes the axial arrangement of the methyl ether present in the ortho cycloadducts. [27] The analysis of the activation enthalpies for the TSs reveals that the ortho approaches are favored over the meta ones; the TS1-en and TS1-ex are less energetic than TS2-en and TS2-ex, in the range of 6.9Ϫ9.4 kcal mol Ϫ1 . Therefore, there is a pronounced regioselectivity for this 1,3-DC reaction, in agreement with the experimental results.…”

Section: -Dc Reaction Of the Nitrone R1 With Methyl Vinyl Ethermentioning

confidence: 99%

Theoretical Study of 1,3-Dipolar Cycloaddition Reactions with Inverse Electron Demand − A DFT Study of the Lewis Acid Catalyst and Solvent Effects in the Reaction of Nitrones with Vinyl Ethers

Domingo

2000

Eur. J. Org. Chem.

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The molecular mechanism for the inverse electron demand 1,3-dipolar cycloaddition of nitrones with vinyl ethers has been characterized using density functional theory methods with the B3LYP functional and the 6−31G* basis set. Relative rates, regioselectivity, endo/exo stereoselectivity, Lewis acid catalyst and solvent effects are analyzed and discussed. Four reactive channels associated with the formation of two pairs of diasteromeric regioisomers have been characterized. Analysis of the geometries of the corresponding transition structures shows that the reaction in the gas phase takes place by an asynchronous concerted mechanism. These 1,3-dipolar

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“…Therefore, dipolar interactions also affect the lengthening of the CÀH or CÀO bond, as had been suggested. [12] However, it may also be indirect, through the electron population.…”

mentioning

confidence: 99%

The Origin of One‐Bond C–H Coupling Constants in OCH Fragments: Not Primarily n_O→${{\rm \sigma} {{\ast \hfill \atop {\rm CH}\hfill}}}$ Delocalization

et al. 2005

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Conforming couples: Coupling constants 1JCH and CH bond lengths were calculated for various conformations of tetrahydropyran, ethyl methyl ether, and dimethyl ether. The dependence of 1JCH on the H‐C‐O‐C dihedral angle does not parallel the nO→${{{\rm \sigma} {{\ast \hfill \atop {\rm {\rm CH}}\hfill}}}}$ delocalization (see picture). Dipolar interactions that affect electron densities are proposed to be responsible.

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The origin of the anomeric effect: conformational analysis of 2-methoxy-1,3-dimethylhexahydropyrimidine

Cited by 128 publications

References 3 publications

Microwave Spectroscopy of Biomolecular Building Blocks

Microwave Spectroscopy of Biomolecular Building Blocks

Theoretical Study of 1,3-Dipolar Cycloaddition Reactions with Inverse Electron Demand − A DFT Study of the Lewis Acid Catalyst and Solvent Effects in the Reaction of Nitrones with Vinyl Ethers

The Origin of One‐Bond C–H Coupling Constants in OCH Fragments: Not Primarily n_O→${{\rm \sigma} {{\ast \hfill \atop {\rm CH}\hfill}}}$ Delocalization

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The origin of the anomeric effect: conformational analysis of 2-methoxy-1,3-dimethylhexahydropyrimidine

Cited by 128 publications

References 3 publications

Microwave Spectroscopy of Biomolecular Building Blocks

Microwave Spectroscopy of Biomolecular Building Blocks

Theoretical Study of 1,3-Dipolar Cycloaddition Reactions with Inverse Electron Demand − A DFT Study of the Lewis Acid Catalyst and Solvent Effects in the Reaction of Nitrones with Vinyl Ethers

The Origin of One‐Bond C–H Coupling Constants in OCH Fragments: Not Primarily nO→${{\rm \sigma} {{\ast \hfill \atop {\rm CH}\hfill}}}$ Delocalization

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The Origin of One‐Bond C–H Coupling Constants in OCH Fragments: Not Primarily n_O→${{\rm \sigma} {{\ast \hfill \atop {\rm CH}\hfill}}}$ Delocalization