(2-Bromoethyl)diphenylsulfonium Trifluoromethanesulfonate

Typical　Procedure (R¹ = R² = 2,6-diisopropylphenyl) : (2-Bromoethyl)diphenylsulfonium Trifluoromethanesulfonate (610 mg, 1.38 mmol) is added to a stirred solution of N,N’-bis(2,6-diisopropylphenyl)formamidine (400 mg, 1.10 mmol) and diisopropylethylamine (0.48 mL, 2.75 mmol) in 8 mL of anhydrous MeCN under a nitrogen atmosphere. After refluxing for 1.5 h, the mixture is cooled to rt and the solvent is reduced to half in volume by nitrogen overflow. Ether is added and the mixture is stirred until a precipitate formed. The precipitate is collected by filtration and washed in the following order: Hot (100-110 °C) toluene (1-4 mL), diethyl ether (3 mL), water (1-4 mL) and diethyl ether (3 mL). Then it is dried in vacuo to give 1,3-bis(2,6-diisopropylphenyl)imidazolinium trifluoromethanesulfonate (532 mg, 90%) as an amorphous powder.