Stereoselectivity and carbon-14 isotope effect in methyl group transfer from s-butyldimethylsulphonium to para-thiocresolate ion

The large rate-difference, observed in transfer of the prochiral methyl groups from (RS)-s-butyldimethylsulphonium p-toluenesulphonate (1) to p-thiocresolate, is attributed, by stereospecific 14C-labelling, to the compound operation of a small diastereotopic selectivity (< 4%) and a large isotope effect.