反应详情

温度

-78 °C

A solution of 27.2 g (0.1 mole) of 1,4-dibromo-2,5-difluorobenzene in 200 ml of ether was blanketed with argon and cooled to -78° C. To this mixture was added 42 ml of n-butyl lithium (2.4 M; 0.10 mole) dropwise via an addition funnel. The solution was stirred at -78° C. for 15 minutes, then allowed to warm to -45° C. To the anion was added 13 ml of 3-ethoxy-2-cyclopentenone (0.10 mole); the solution was kept at -45° for 30 minutes and was then warmed slowly to room temperature. The mixture was poured into 250 ml of 1 N hydrochloric acid, stirred for 30 minutes, and extracted with ethyl acetate; the organic phases were combined, washed with water, dried over magnesium sulfate, and concentrated. The crude product was purified via silica gel chromatography using an 80:20 chloroform ethyl acetate mixture to give 14.2 g of the desired product; mp 129°-131° C.

1. temperatureto warm to -45° C
2. waitthe solution was kept at -45° for 30 minutes
3. temperaturewas then warmed slowly to room temperature
4. stirringstirred for 30 minutes
5. extractionextracted with ethyl acetate
6. washwashed with water
7. dry with materialdried over magnesium sulfate
8. concentrationconcentrated
9. customThe crude product was purified via silica gel chromatography