反应详情

A portion (2.0 g) of the compound obtained in Example 1 was dissolved in anhydrous methylene chloride (20 ml) and to the solution was added N-bromosuccinimide (NBS; 1.01 g). The mixture was stirred for 3 days at room temperature. After adding water, the reaction mixture was extracted three times with methylene chloride. The organic layers were combined, washed with saturated aqueous solution of sodium chloride and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (methylene chloride/hexane/ethyl acetate=5:5:1) and further crystallized from an ether/hexane mixed solvent to yield 2.02 g (83%) of the titled compound as pale yellow crystals.

1. extractionthe reaction mixture was extracted three times with methylene chloride
2. washwashed with saturated aqueous solution of sodium chloride
3. dry with materialdried over anhydrous sodium sulfate
4. distillationThe solvent was distilled off under reduced pressure
5. customthe residue was purified by silica gel column chromatography (methylene chloride/hexane/ethyl acetate=5:5:1)
6. customfurther crystallized from an ether/hexane mixed solvent