An ab initio molecular orbital study of the conformational energies of 2-alkyltetrahydro-2H-pyrans (tetrahydropyrans, oxacyclohexanes, oxanes)

F. Freeman, J. A. Kasner, Marc Kasner, W. J. Hehre

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21 Citations (Scopus)

Abstract

Ab initio Hartree-Fock and Density Functional Theory calculations were used to obtain the geometries and relative energies of the rotamers in the chair conformations of 2-alkyltetrahydro-2H-pyrans and 2- (trimethylsilyl)tetrahydro-2H-pyran. The MP2/6-31G*//6-31G* conformational energies (-ΔG°or A values, kcal/mol) of the 2-alkyltetrahydro-2H-pyrans (Me = 3.18; Et = 3.04; i-Pr = 3.03; t-Bu = 7.56; neo Pent = 2.84) and 2- (trimethylsilyl)tetrahydro-2H-pyran (SiMe3 = 4.77) are larger than those calculated for the corresponding alkylcyclohexanes and 2-alkyltetrahydro-2H- thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes). Plots of the calculated conformational energies for the 2-substituted tetrahydro-2H-pyrans versus the calculated -ΔG°values for the corresponding alkylcyclohexanes (slope = 1.34 and r = 0.983) and for the corresponding 2-substituted tetrahydro-2H-thiopyrans (slope = 2.01 and r = 0.986) are linear. (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)19-39
Number of pages21
JournalJournal of Molecular Structure: THEOCHEM
Volume496
Issue number1-3
DOIs
StatePublished - 7 Jan 2000

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Pyrans
Molecular orbitals
molecular orbitals
slopes
seats
energy
plots
density functional theory
Density functional theory
Conformations
geometry
Geometry

Keywords

  • Conformational energies
  • Hyperconjugative orbital interactions
  • Oxacyclohexanes
  • Rotamers
  • Stereoelectronic effects

Cite this

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title = "An ab initio molecular orbital study of the conformational energies of 2-alkyltetrahydro-2H-pyrans (tetrahydropyrans, oxacyclohexanes, oxanes)",
abstract = "Ab initio Hartree-Fock and Density Functional Theory calculations were used to obtain the geometries and relative energies of the rotamers in the chair conformations of 2-alkyltetrahydro-2H-pyrans and 2- (trimethylsilyl)tetrahydro-2H-pyran. The MP2/6-31G*//6-31G* conformational energies (-ΔG°or A values, kcal/mol) of the 2-alkyltetrahydro-2H-pyrans (Me = 3.18; Et = 3.04; i-Pr = 3.03; t-Bu = 7.56; neo Pent = 2.84) and 2- (trimethylsilyl)tetrahydro-2H-pyran (SiMe3 = 4.77) are larger than those calculated for the corresponding alkylcyclohexanes and 2-alkyltetrahydro-2H- thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes). Plots of the calculated conformational energies for the 2-substituted tetrahydro-2H-pyrans versus the calculated -ΔG°values for the corresponding alkylcyclohexanes (slope = 1.34 and r = 0.983) and for the corresponding 2-substituted tetrahydro-2H-thiopyrans (slope = 2.01 and r = 0.986) are linear. (C) 2000 Elsevier Science B.V.",
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An ab initio molecular orbital study of the conformational energies of 2-alkyltetrahydro-2H-pyrans (tetrahydropyrans, oxacyclohexanes, oxanes). / Freeman, F.; Kasner, J. A.; Kasner, Marc; Hehre, W. J.

In: Journal of Molecular Structure: THEOCHEM, Vol. 496, No. 1-3, 07.01.2000, p. 19-39.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - An ab initio molecular orbital study of the conformational energies of 2-alkyltetrahydro-2H-pyrans (tetrahydropyrans, oxacyclohexanes, oxanes)

AU - Freeman, F.

AU - Kasner, J. A.

AU - Kasner, Marc

AU - Hehre, W. J.

PY - 2000/1/7

Y1 - 2000/1/7

N2 - Ab initio Hartree-Fock and Density Functional Theory calculations were used to obtain the geometries and relative energies of the rotamers in the chair conformations of 2-alkyltetrahydro-2H-pyrans and 2- (trimethylsilyl)tetrahydro-2H-pyran. The MP2/6-31G*//6-31G* conformational energies (-ΔG°or A values, kcal/mol) of the 2-alkyltetrahydro-2H-pyrans (Me = 3.18; Et = 3.04; i-Pr = 3.03; t-Bu = 7.56; neo Pent = 2.84) and 2- (trimethylsilyl)tetrahydro-2H-pyran (SiMe3 = 4.77) are larger than those calculated for the corresponding alkylcyclohexanes and 2-alkyltetrahydro-2H- thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes). Plots of the calculated conformational energies for the 2-substituted tetrahydro-2H-pyrans versus the calculated -ΔG°values for the corresponding alkylcyclohexanes (slope = 1.34 and r = 0.983) and for the corresponding 2-substituted tetrahydro-2H-thiopyrans (slope = 2.01 and r = 0.986) are linear. (C) 2000 Elsevier Science B.V.

AB - Ab initio Hartree-Fock and Density Functional Theory calculations were used to obtain the geometries and relative energies of the rotamers in the chair conformations of 2-alkyltetrahydro-2H-pyrans and 2- (trimethylsilyl)tetrahydro-2H-pyran. The MP2/6-31G*//6-31G* conformational energies (-ΔG°or A values, kcal/mol) of the 2-alkyltetrahydro-2H-pyrans (Me = 3.18; Et = 3.04; i-Pr = 3.03; t-Bu = 7.56; neo Pent = 2.84) and 2- (trimethylsilyl)tetrahydro-2H-pyran (SiMe3 = 4.77) are larger than those calculated for the corresponding alkylcyclohexanes and 2-alkyltetrahydro-2H- thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes). Plots of the calculated conformational energies for the 2-substituted tetrahydro-2H-pyrans versus the calculated -ΔG°values for the corresponding alkylcyclohexanes (slope = 1.34 and r = 0.983) and for the corresponding 2-substituted tetrahydro-2H-thiopyrans (slope = 2.01 and r = 0.986) are linear. (C) 2000 Elsevier Science B.V.

KW - Conformational energies

KW - Hyperconjugative orbital interactions

KW - Oxacyclohexanes

KW - Rotamers

KW - Stereoelectronic effects

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EP - 39

JO - Journal of Molecular Structure: THEOCHEM

JF - Journal of Molecular Structure: THEOCHEM

SN - 0166-1280

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