Abstract
Conformational isomerization of 5-methyl- and 2,2,5-trimethyl-1,3-dithianes was studied using quantum-chemical HF/6-31G(d), HF/pVDZ, and PBE/3z approximations. The potential energy surface of molecules of both compounds is shown to contain the main minimum corresponding to the equatorial chair conformer C-5e. The calculated potential barriers of the conformational isomerization were found. Based on the experimental (1H NMR) and theoretical vicinal coupling constants the ΔG 0 values were determined of the methyl group at the ring C5 atom. The reasons for the distinctions between the values of this parameter from the ΔG 0, obtained by energy minimizations of the equatorial and axial chair conformers are discussed.
Published Version
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