Conformational investigation of ?-methylthio and ?-phenylthio derivatives of acetone and cyclohexanone by molecular mechanics. An x-ray study of ?-phenylthioacetone

Abstract

A conformational investigation of α-methylthioacetone, α-methylthiocyclohexanone, α-phenylthioacetone, and α-phenylthiocyclohexanone was undertaken in the MM2(87) force field. In all cases theac-G rotamers with unidirectional orientation of the C=O and S-R bonds are preferred in accordance with the experimental investigations. In all cases the energy of dipole-dipole interaction makes a contribution to the stabilization of these forms. For the eclipsedsp conformers the relatively high calculated values of the energies contradict the data of the experimental investigations, which take account of their participation in the equilibrium. X-ray crystallographic analysis of α-phenylthioacetone (3) showed that thesp-T structure with a planar orientation of the thioanisole fragment is realized in the solid phase.