反应详情

To a solution of the product of step 3 (40.5 g, 139 mmol) in CCl4 (500 mL) and CHCl3 (2 L) was added dropwise a solution of Br2 in CCl4 (50 mL). After addition was completed, the mixture was washed with saturated NaHCO3 (500 mL) and Na2S2O8 (2×250 mL). The pale yellow solution was dried over Na2SO4 and concentrated to dryness. The residue was stirred in 50 % EtO2 /hexane for 20 h and filtered to give 49 g of the title compound.

1. additionAfter addition
2. washthe mixture was washed with saturated NaHCO3 (500 mL) and Na2S2O8 (2×250 mL)
3. dry with materialThe pale yellow solution was dried over Na2SO4
4. concentrationconcentrated to dryness
5. filtrationfiltered