反应详情

To a solution of 24.8 g (100 mmole) of the compound obtained in step 1 dissolved in 50 ml of acetic acid was added 40% HBr, which was heated to reflux for 8 hours. The reaction solution was poured into ice-water. The resultant solution was extracted with ethyl acetate (100 ml×3), dried over Na2SO4 and concentrated to obtain residue, which was purified by silica gel column chromatography using a mixture of hexane and ethyl acetate (1:1) to obtain 23.0 g (yield 100%) of the title compound containing a portion of orthoisomer (approximately one-eighth).

1. temperaturewas heated
2. temperatureto reflux for 8 hours
3. extractionThe resultant solution was extracted with ethyl acetate (100 ml×3)
4. dry with materialdried over Na2SO4
5. concentrationconcentrated
6. customto obtain residue, which
7. customwas purified by silica gel column chromatography
8. additiona mixture of hexane and ethyl acetate (1:1)