Conformational studies by dynamic NMR. 80. Cog-wheel effect in the stereolabile helical enantiomers of dimesityl sulfoxide and sulfone
The 1H NMR solution spectra of the title compounds display anisochronous lines for the o-methyl substituents below -170 °C, due to the existence of two propeller-like M and P conformational enantiomers. The free energies of activation for the i
Synthesis of symmetric diaryl sulfones with dimethyl sulfate
In this procedure dimethyl sulfate was used for preparation of symmetric diaryl sulfones. First, dimethyl sulfate was treated with pyridine, then activated by Tf2O to generate SO2 as the functional group for synthesis of diaryl sulfones. It is noticeable that this reaction was carried out in moderate conditions and products obtained in short times and good yields.