General procedure for the synthesis of 6-bromothiochroman-4-one and 6,8-dibromothiochroman-4-one from thiochroman-4-one: Anhydrous aluminum trichloride (1.81 g, 13.5 mmol) and methylene chloride (1 mL) were added to a round bottom flask at room temperature. After stirring for about 7 min under nitrogen protection, a solution of thiocolchroman-4-one (1.11 g, 6.77 mmol) in dichloromethane (1 mL) was slowly added. Stirring was continued for 10 minutes and then a solution of bromine (1.19 g, 7.44 mmol) in dichloromethane (2 mL) was added dropwise. The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the mixture was poured into ice water (50 mL) and the aqueous phase was extracted with ethyl acetate three times. The organic phases were combined, washed once with saturated saline and dried over anhydrous sodium sulfate. The crude product was purified by fast column chromatography (15% ethyl acetate/85% hexane) to give a mixture of 6-bromothiochroman-4-one (0.648 g, 34% purity, 13% yield) and 6,8-dibromothiochroman-4-one (66% purity, 20% yield).The NMR data for 6,8-dibromothiochroman-4-one were as follows:1H NMR (300 MHz , CDCl3, δ): 8.18 (dd, J = 2.2, 0.7 Hz, Ar-H, 1H), 7.77 (dd, J = 2.2, 0.7 Hz, Ar-H, 1H), 3.22 (m, CH2, 2H), 2.94 (m, CH2, 2H). 13C NMR (75 MHz, CDCl3): δ 192.0, 142.5 , 139.1, 136.0, 131.0, 122.2, 118.2, 37.8, 26.0.
