反应详情

A solution of bromine (6.1 ml) in dichloromethane (50 ml) was added dropwise over 3 hours at 10°-15° C. under nitrogen to a stirred solution of 1-[1-(3,4-dichlorophenyl)cyclopentyl]ethanone (31.9 g) in a mixture of methanol (60 ml) and dichloromethane (10 ml), then the mixture was stirred at ambient temperature for 2.5 hours and poured into an excess of ice-water. The aqueous layer was separated and washed with dichloromethane 3×100 ml), then the combined organic solutions were washed with saturated aqueous sodium hydrogencarbonate solution (2×100 ml) and water (100 ml), dried over calcium chloride, and the solvent removed in vacuo. The residue was distilled in vacuo, and the fraction of b.p. >174° C./1.3 mbar was collected and redistilled. Material of b.p. >182° C./2.6 mbar in this second distillation was collected and redistilled to give 2-bromo-1-[1-(3,4-dichlorophenyl)cyclopentyl]ethanone as a pale yellow oil (11.8 g), b.p. 156°-162° C./0.4 mbar.

1. customThe aqueous layer was separated
2. washwashed with dichloromethane 3×100 ml), then the combined organic solutions
3. washwere washed with saturated aqueous sodium hydrogencarbonate solution (2×100 ml) and water (100 ml)
4. dry with materialdried over calcium chloride
5. customthe solvent removed in vacuo
6. distillationThe residue was distilled in vacuo
7. customthe fraction of b.p. >174° C./1.3 mbar was collected
8. distillationredistilled
9. distillationMaterial of b.p. >182° C./2.6 mbar in this second distillation
10. customwas collected
11. distillationredistilled