The general procedure for the synthesis of 2-fluoro-4-methylsulfinylaniline from 2-fluoro-4-iodoaniline and sodium methanesulfinic acid was as follows: firstly, to a solution of 2-fluoro-4-iodoaniline (206.8 g, 872.3 mmol) in DMSO (1.1 L) was added, in order, copper(II)-benzene trifluoromethanesulfonate complex (30.74 g, 61.1 mmol), sodium methanesulfinic acid ( 106.9 g, 1.047 mol) and N,N'-dimethylethylenediamine (13.2 mL, 122 mmol). Subsequently, the reaction vessel was placed in an oil bath preheated to 120°C and the reaction mixture was stirred overnight. Upon completion of the reaction, the mixture was cooled to room temperature, diluted with water and extracted several times with EtOAc. The organic extracts were combined, washed five times with brine, dried over MgSO4 and concentrated under reduced pressure to remove the solvent. The resulting purple solid was washed with diisopropyl ether and then dried in a vacuum oven at room temperature to constant weight to give 151.5 g of dark purple solid in 92% yield. The product was identified by 1H NMR (DMSO-d6): δ 7.41 (d, 1H, J = 8.5 Hz), 6.87 (t, 1H, J = 8.6 Hz), 6.19 (s, 2H), 3.10 (s, 3H); MS m/z 190.3 (M+).
