Solvent effect on the conformational preference of the carbanions derived from benzyl methyl sulfoxide

Abstract

The effect of solvent on the stereochemical course of deuteration of benzyl methyl sulfoxide has been studied by two methods. In the first, the relative rates of exchange of the diastereotopic methylene protons were found to vary from 14:1 (D₂O/NaOD) to 0.5:1 (t-butanol-OD/NaO-t-butyl). Experiments on quenching α-lithiobenzyl methyl sulfoxide with D₂O gave the same diastereomers in ratios ranging from 1.7:1 (DMSO) to 0.065:1 (THF). The significance of these findings in relation to previous work on conformational stabilities of α-sulfinyl carbanions is discussed.