first-order kinetics and seems to be mainly an enthalpic process with a small negative activation entropy, as revealed by polarimetric measurements at low temperatures. This is in accordance with Cα–S bondrotation as the rate-determining step. The salts [R1C(R2)SO2tBu]Li have half-lives of racemization in the order of several hours at –105 °C. The deuteriation of the salts at –105 °C with CF3CO2D