反应详情

The product from step (ii) (30 g) was dissolved in dry DCM (200 ml). The solution was stirred at rt whilst N-bromosuccinimide (27 g) was added portion wise. The mixture was stirred at rt overnight. 20% (w/v)-Sodium sulfate (200 ml) was added and the separated aqueous phase extracted with DCM. The combined organic phase was washed with saturated NaHCO3 solution and brine. After concentration in vacuo, the residue was dissolved in EtOAc, washed with water, brine and dried. The solution was filtered through silica gel. The filtrate was concentrated in vacuo and dissolved in a mixture of diethyl ether and isohexane (1/1, 200 ml) to give the subtitle compound (26 g). The solvent was removed to give a residue, which was purified by column chromatography (EtOAc/isohexane), which afforded 2.5 g. The solids were combined to give the subtitle compound as a yellow solid. Yield 28.5 g. Melting point: 148-150° C.

1. additionwas added portion wise
2. extractionthe separated aqueous phase extracted with DCM
3. washThe combined organic phase was washed with saturated NaHCO3 solution and brine
4. concentrationAfter concentration in vacuo
5. dissolutionthe residue was dissolved in EtOAc
6. washwashed with water, brine
7. customdried
8. filtrationThe solution was filtered through silica gel
9. concentrationThe filtrate was concentrated in vacuo
10. dissolutiondissolved in a mixture of diethyl ether and isohexane (1/1, 200 ml)