反应详情

To a solution of the product obtained in EXAMPLE 108 (5.0 g) in ethanol (30 ml), 3N aqueous sodium hydroxide (30 ml) was added and the mixture was stirred for 10 minutes under reflux. The aqueous solution was concentrated under reduced pressure and washed with ether, acidified to pH 3 with 2N hydrochloric acid and extracted four times with ethyl acetate. The combined organic layer was washed with saturated sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The residue was crystallized from ethyl acetate-hexane to give 2.96 g (68%) of the objective compound.

1. temperatureunder reflux
2. concentrationThe aqueous solution was concentrated under reduced pressure
3. washwashed with ether
4. extractionextracted four times with ethyl acetate
5. washThe combined organic layer was washed with saturated sodium chloride
6. dry with materialdried over anhydrous sodium sulfate
7. concentrationconcentrated under reduced pressure
8. customThe residue was crystallized from ethyl acetate-hexane