Conformational Energies in Organic Six-Membered Cyclic Sulfoxides

Abstract

pounds 1, 2, and 4 are more stable than the equatorial forms by 6.0, 20.0, and 9.9 kJ mol −1 , respectively, the equatorial geometry of 3 is 3.0 kJ mol −1 more stable than the axial form. The diaxial conformations of 5 and 7 are calculated to have similar energies, but the diaxial form of 6 is about 43 kJ mol −1 less stable than that of 5 or 7.

Effect of Sulfur Oxidation on the Transmission Mechanism of 4JHH NMR Coupling Constants in 1,3-Dithiane

“…The relevant role played by the sulfur oxidation along the 4 J H eq -H eq four-bond coupling pathway is also appreciated when analyzing the 1 H NMR spectra for 3 and 4. It is noted that in 3 the SdO groups are in equatorial position (this is the only stable form [55][56][57] for this compound) and was observed a doublet of triplets for H 2eq signal (part b of Figure 3) due to the geminal coupling with H 2ax and the two four-bond couplings with H 4eq and H 6ax . A similar pattern is observed for H 2eq in 4, however in this case a long-range coupling, 4 J H 2ax ,H 6ax is also observed for H 2ax , which suggests that the presence of the SdO moiety in axial orientation enhances the ability of this coupling pathway for transmitting that long-range SSCC.…”

Density functional theory (DFT) calculations of conformational energies and interconversion pathways in 1,2,7-thiadiazepane

“…As a continuation of our interest in the conformations of medium ring sized heterocycles, [17][18][19][20] this study was undertaken in order to investigate the conformational analysis of 1,2,7-thiadiazepane (Scheme 1) by computational methods to determine their preferred conformers. The effects of changes in bond length, bond angle and torsion angle of these compounds were also of interest.…”