title: Linear free energy relationship for the anomeric effect: MP2, DFT and ab initio study of 2-substituted-1,4-dioxanes.
abstract: The anomeric effect of 2-substituted 1,4-dioxane derivatives was calculated and compared with the values for substituted cyclohexane. The bond lengths, bond angles, torsion angles, and relative energies of axial and equatorial conformers of 2-substituted 1,4-dioxanes were calculated by the second-order Møller-Plesset (MP2), density functional theory (DFT/B3LYP), and Hartree-Fock (HF) methods using 6-31G(∗) basis set. The energy differences between the axial and equatorial conformers, endo and exo-anomeric effects, repulsive non-bond and H-bonding interactions were investigated. A linear free energy relationship (LFER) between calculated (MP2/6-31G(∗)) anomeric effect and inductive substituent constants (σ(I)) was obtained for 2-substituted-1,4-dioxanes (slope=6.19 and r(2)=0.967). The calculated energy differences indicate lower equatorial orientation for 2-substituted-1,4-dioxanes compared to the 2-substituted-tetrahydropyrans. The contribution of resonance, hyperconjugation, inductive, steric, hydrogen bonding, electrostatic interaction, and level of theory influences the anomeric effect.
authors.affiliation: Department of Chemistry, Isfahan University of Technology, 8415483111 Isfahan, Iran. Dabbagh@cc.iut.ac.ir
authors.forename: Hossein A
authors.initials: HA
authors.lastname: Dabbagh
authors.forename: Marzie
authors.initials: M
authors.lastname: Naderi
authors.forename: Alireza Najafi
authors.initials: AN
authors.lastname: Chermahini
mesh_terms: D002236:Carbohydrate Conformation; D004146:Dioxanes / Q000737:chemistry*; D016014:Linear Models; D008958:Models, Molecular; D011789:Quantum Theory; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D004146:Dioxanes