反应详情

0.7 g (6 mmol) of methyl acetoacetate are added dropwise at 0°-5° C. to a suspension of 0.2 g (6.6 mmol) of 80% strength sodium hydride in 8 ml of anhydrous tetrahydrofuran. After 15 min, 4.9 ml (8 mmol) of 15% strength butyllithium in hexane are added dropwise in the course of 10 min and the mixture is kept at 0° C. for a further 15 min. 0.82 g (2 mmol) of the compound from Example 6 and 10 ml of tetrahydrofuran are then added and the mixture is stirred at 0°-5° C. for 1 h. 1.2 g (20 mmol) of acetic acid in 20 ml of water are then added cautiously, the mixture is extracted three times with ethyl acetate, and the organic phase is washed with sodium chloride solution, dried over sodium sulphate and concentrated in vacuo. The residue is chromatographed on 40 g of 230-400 mesh silica gel (φ 3 cm) using petroleum/ethyl acetate (2:1) to (1:3).

1. waitthe mixture is kept at 0° C. for a further 15 min
2. extractionthe mixture is extracted three times with ethyl acetate
3. washthe organic phase is washed with sodium chloride solution
4. dry with materialdried over sodium sulphate
5. concentrationconcentrated in vacuo
6. customThe residue is chromatographed on 40 g of 230-400 mesh silica gel (φ 3 cm)