反应详情

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%).

1. additionwas added (solution turned red)
2. addition3HF (6.31 mL, 38.7 mmoles) was added
3. additionAfter 5 minutes a suspension of DBH (1,3-dibromo-5,5-dimethylhydanthoin) (11.1 g, 38.7 mmoles) in 25 mL'
4. additionwas added in portions over 30 minutes (solution turned greenish/black)
5. stirringThe solution was stirred for an additional hour
6. temperaturewarmed to 0° C.
7. customThe organic layer was separated
8. washwashed with water
9. dry with materialdried over sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated in vacuo
12. customThe crude material was purified via silica gel chromatography
13. washwas eluted with 20% ethyl acetate 80% heptane to 100% ethyl acetate for 45 minutes