Abstract
Conformational properties and the gauche effect of the two functional groups, hydroxymethyl and methoxymethyl, in hexopyranosides have been studied with ab initio methods using the methyl 2,3,4-trideoxy-α-d-glycero-hexopyranoside (1), methyl 2,3,4-trideoxy-β-d-glycero-hexopyranoside (2), methyl 6-O-methyl-2,3,4-trideoxy-α-d-glycero-hexopyranoside (3), and methyl 6-O-methyl-2,3,4-trideoxy-β-d-glycero-hexopyranoside (4) as models. The geometry of the conformers around the C5−C6 bond for the methyl 2,3,4-trideoxy-d-glycero-hexopyranosides was determined by gradient optimization at the SCF level using the 6-31G*, 6-31+G*, and 6-311++G** basis sets. The optimized geometries were used to calculate the energy of the gauche−trans (gt), trans−gauche (tg), and gauche−gauche (gg) conformers with the 6-31G*, 6-31+G* 6-31+G**, 6-31G**, 6-311G*, and 6-311++G** basis sets. Electron correlation effects were accounted for at the second-order Moller−Plesset perturbation (MP2) level using the 6-31G* basis set and using the adiabatic connection method (ACM) of density functional theory (DFT) using standard 6-31G*, dzvp, and cc-pvtz basis sets. Solvent effects on the stability of conformers were evaluated using a continuum model. At all levels of theory, 1 and 2 prefer the gauche over the trans conformers around the C5−C6 bond. This preference is due to internal hydrogen bonding which is possible in the gg(sc) and gt(−sc) conformers. Solvent effects decrease this preference by ∼0.9 kcal/mol. Methylation of the oxygen of the C6 hydroxyl completely reversed the relative energy of conformers, such that in 3 and 4, the trans conformer is favored. The trans preference is decreased by solvent which stabilized the gauche conformers by 0.7−1.3 kcal/mol with respect to the trans. These results suggest that the gauche preference of the hydroxymethyl group in 1 and 2, is due to the presence of hydrogen bonding and not due to the gauche effect.
Keywords
Conformational isomerismChemistryAb initioBasis setHydroxymethylHydrogen bondAnomeric effectComputational chemistryElectronic correlationAb initio quantum chemistry methodsMolecular geometryMolecular orbitalDensity functional theoryGauche effectCrystallographyMoleculeStereochemistryAnomerOrganic chemistry
Affiliated Institutions
Related Publications
Nucleophilic Degradation of Fenitrothion Insecticide and Performance of Nucleophiles: A Computational Study
Ab initio and density functional theory (DFT) calculations have been performed to understand the destruction chemistry of an important organophosphorus insecticide O,O-dimethyl ...
Merck molecular force field. II. MMFF94 van der Waals and electrostatic parameters for intermolecular interactions
This article defines the parameterization and performance of MMFF94 for intermolecular interactions. It specifies the novel “buffered” functional forms used for treating van der...
Integrated spatial electron populations in molecules: Application to simple molecules
Abstract The electron projection function P ( x , z ) = ∫ ρ( x , y , z ) dy is used to evaluate charge transfer and covalency in two series of molecules, LiX and CH 3 X (X = Li,...
Structure and Dynamics of the Homologous Series of Alanine Peptides: A Joint Molecular Dynamics/NMR Study
The phi,psi backbone angle distribution of small homopolymeric model peptides is investigated by a joint molecular dynamics (MD) simulation and heteronuclear NMR study. Combinin...
<i>A</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> effective core potentials for molecular calculations. II. All-electron comparisons and modifications of the procedure
Recently methods have been developed [L. R. Kahn, P. Baybutt, and D. G. Truhlar, J. Chem. Phys. 65, 3826 (1976)] to replace the core electrons of atoms by ab initio effective co...
Publication Info
- Year
- 1997
- Type
- article
- Volume
- 101
- Issue
- 15
- Pages
- 2992-2999
- Citations
- 49
- Access
- Closed
External Links
Social Impact
Altmetric
PlumX Metrics
Social media, news, blog, policy document mentions
Citation Metrics
49
OpenAlex
Cite This
Igor Tvaroška,
Jeremy P. Carver
(1997).
<i>Ab Initio</i> Molecular Orbital Calculation of Carbohydrate Model Compounds. 6. The Gauche Effect and Conformations of the Hydroxymethyl and Methoxymethyl Groups.
The Journal of Physical Chemistry B
, 101
(15)
, 2992-2999.
https://doi.org/10.1021/jp963766n
Identifiers
- DOI
- 10.1021/jp963766n