General procedure: The NaOH solution (15% w/w, 8 mL) was cooled to 5 °C and Br2 (0.4 mL, 15 mmol, 3 eq.) was added dropwise while keeping the temperature of the mixture below 10 °C. The NaOH solution was cooled to 5 °C and Br2 (0.4 mL, 15 mmol, 3 eq.) was added to the mixture. Subsequently, phenylmethyl sulfone (5 mmol, 1 eq.) was added all at once. The reaction mixture was stirred at 75 °C for the indicated time (see Table 1). After completion of the reaction, the mixture was cooled to room temperature, the precipitate was collected by filtration, washed with H2O, dried in air and finally recrystallized by 2-PrOH. Detailed characterization data of the resulting tribromomethyl phenyl sulfone are given in the Supplementary Material.
