反应详情

The product from step (ii) (30 g) was dissolved in dry dichloromethane (200 ml). The solution was stirred at rt whilst NBS (27 g) was added portionwise. 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 sodium hydrogen carbonate solution and brine. After concentration in vacuo, the residue was dissolved in ethyl acetate, washed with water, brine and dried. The solution was filtered through silica gel and concentrated in vacuo. The residue was triturated with diethyl ether and isohexane (1/1, 200 ml) then filtered to give the subtitle compound (26 g). The filtrate was concentrated in vacuo and the residue purified by column chromatography (ethyl acetate/isohexane) to give a further 2.5 g of product. The solids were combined to give the subtitle compound as a yellow solid. Yield 28.5 g. mp 148-50° C.

1. additionwas added portionwise
2. extractionthe separated aqueous phase extracted with DCM
3. washThe combined organic phase was washed with saturated sodium hydrogen carbonate solution and brine
4. concentrationAfter concentration in vacuo
5. dissolutionthe residue was dissolved in ethyl acetate
6. washwashed with water, brine
7. customdried
8. filtrationThe solution was filtered through silica gel
9. concentrationconcentrated in vacuo
10. customThe residue was triturated with diethyl ether and isohexane (1/1, 200 ml)
11. filtrationthen filtered