4-Bromophenol → 8-((4-Bromophenoxy)difluoromethyl)-1,4-dioxaspiro[4.5]decane

Participants

Reaction Steps

Trifluoromethanesulfonic acid (0.681 mL, 7.82 mmoles) was added dropwise to a stirred solution of 8-[1,3]dithian-2-ylidene-1,4-dioxa-spiro[4,5]decane (2000 mg, 7.740 mmoles) in 25 mL of dichloromethane at −22° C. The solution was allowed to warm to room temperature and stirred for 30 minutes The black reaction mixture was cooled to −720C and a solution of 4-bromo-phenol (2010 mg, 11.6 mmoles) and triethylamine (1.90 mL, 13.6 mmoles) in 25 mL of dichloromethane was added (solution turned red). The reaction was allowed to stir for an hour at −72° C., before NEt3.3HF (6.31 mL, 38.7 mmoles) was added. After 5 minutes a suspension of DBH (1,3-dibromo-5,5-dimethylhydanthoin) (11.1 g, 38.7 mmoles) in 25 mL's of dichloromethane was added in portions over 30 minutes (solution turned greenish/black). The solution was stirred for an additional hour, then warmed to 0° C. and poured into a solution of 1 N NaOH. The organic layer was separated, washed with water, dried over sodium sulfate, filtered and concentrated in vacuo. The crude material was purified via silica gel chromatography and was eluted with 20% ethyl acetate 80% heptane to 100% ethyl acetate for 45 minutes. The isolated product was taken on directly to the next step. (2.811 g, 24.9%).

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