Microwave spectrum, centrifugal perturbation, dipole moment, and conformation of 5-methyl-1,3-dioxane

Mamleev, A. Kh.; Galeev, R. V.; Gunderova, L. N.; Faizullin, M. G.; Shapkin, A. A.

doi:10.1007/s10947-008-0088-2

Cited by 5 publications

(2 citation statements)

References 10 publications

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“…According to the microwave spectroscopy data, the carbon and heteroatom fragments of the C eq conformer of 5-methyl-1,3-dioxane (III) are slightly flattened as compared to unsubstituted analog I [31].…”

Section: Methodsmentioning

confidence: 98%

Computer simulation of conformational transformations of 1,3-dioxanes and their 2-sila and 2-bora analogs

Кузнецов

2014

Russ J Org Chem

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Section: Methodsmentioning

confidence: 98%

Computer simulation of conformational transformations of 1,3-dioxanes and their 2-sila and 2-bora analogs

Кузнецов

2014

Russ J Org Chem

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“…Local minima correspond to axial chair, 1,4-twist (1,4-T), and 2,5-twist (2,5-T) conformers, and transition states (TS) have half-chair (HC), sofa (S), and unsymmetrical boat (B) structures. According to the microwave spectroscopy data, the carbon fragment in 5-methyl-1,3-dioxane is flatter than the heteroatom-containing moiety [11]. Unsymmetrically substituted cyclic formaldehyde acetals were found to be characterized by more complex PES [6][7][8].…”

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confidence: 99%

Conformational analysis of 4,4-dimethyl-1,3-dioxane

Faizullin

Mamleev

2011

Russ J Org Chem

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The potential energy surface of 4,4-dimethyl-1,3-dioxane molecule was analyzed in terms of the density functional theory at the PBE/cc-pVDZ and B3PW91/aug-cc-pVDZ levels. Eight energy minima were revealed with account taken of enantiomeric structures, the corresponding transition states were found, and the most probable chair-chair conformational isomerization pathways were proposed. 1,3-Dioxanes are classical model structures for conformational analysis; they possess interesting structural and a number of practically important properties and are used as reagents in large-scale and fine organic synthesis [1-3]. In particular, 4,4-dimethyl-1,3-dioxane is a starting compound in the large-scale manufacture of isoprene [1], as well as in laboratory syntheses of 3-amino alcohols [3]. Nonempirical computer simulations previously showed that the global minimum on the potential energy surface (PES) of unsubstituted [4] and 2-methyl-[5], 4-methyl-[6], 4-phenyl-[7], 4-trifluoromethyl-[8], 5-methyl-[9]and 5-isopropyl-substituted 1,3-dioxanes [10] is occupied by chair (C) or equatorial chair conformer. Local minima correspond to axial chair, 1,4-twist (1,4-T), and 2,5-twist (2,5-T) conformers, and transition states (TS) have half-chair (HC), sofa (S), and unsymmetrical boat (B) structures. According to the microwave spectroscopy data, the carbon fragment in 5-methyl-1,3-dioxane is flatter than the heteroatom-containing moiety [11]. Unsymmetrically substituted cyclic formaldehyde acetals were found to be characterized by more complex PES [6][7][8]. However, contrary to the expectations, RHF/6-31G(d,p) study on conformational isomerization of unsymmetrically substituted 4,4-dimethyl-1,3-dioxane (I) revealed relatively small number of minima and maxima on the PES [12]. The goal of the present study was to analyze possible conformational isomerization pathways of 4,4-dimethyl-1,3-dioxane (I) with the use of PBE and B3PW91 hybrid exchangecorrelation functionals and cc-pVDZ Dunning's basis set built in Gaussian 98 [13].According to the 1 H NMR data [2], molecules I at room temperature undergo fast interconversion between two energy-degenerate chair conformers C 1 and C 2 with a fairly low energy barrier (Scheme 1).

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Structure and spectra of 1,3-dioxanes. microwave spectrum, structural parameters, and ab initio calculations of 5-methyl-1,3-dioxane

et al. 2010

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Microwave spectrum, centrifugal perturbation, dipole moment, and conformation of 5-methyl-1,3-dioxane

Cited by 5 publications

References 10 publications

Computer simulation of conformational transformations of 1,3-dioxanes and their 2-sila and 2-bora analogs

Computer simulation of conformational transformations of 1,3-dioxanes and their 2-sila and 2-bora analogs

Conformational analysis of 4,4-dimethyl-1,3-dioxane

Structure and spectra of 1,3-dioxanes. microwave spectrum, structural parameters, and ab initio calculations of 5-methyl-1,3-dioxane

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