反应详情

Under argon, 1.9 ml of a 1 molar solution of lithium bis-(trimethylsilyl)-amide in THF are added dropwise to a solution, cooled to −78° C., of 0.5 g (1.88 mmol) of the compound from Example 1 in 20 ml of THF such that the temp. of the mixture does not exceed −65° C. After the addition has ended, stirring is continued at −78° C. for 10 min, and 0.26 g (2.25 mmol) of allyl bromide are then added in one portion. Immediately afterwards, the cooling bath is removed and the mixture is allowed to warm to room temp. After 16 h of stirring at room temp., the mixture is taken up in ammonium chloride solution and ethyl acetate and the aqueous phase is extracted twice with ethyl acetate. The combined organic phases are dried over sodium sulphate and then concentrated. The residue was chromatographed over silica gel (mobile phase: dichloromethane). Yield: 255 mg (44%) of a colourless oil. 1H-NMR (200 MHz; CDCl3) δ[ppm]=1.55-2.2 (br m,6H), 2.3 (m, 2H), 2.61 (m,1H), 3.12 (d,1H), 3.3 (d,1H), 4.91 (m,1H), 5.05 (dd,1H), 5.11 (dd, 1H), 5.8 (ddt,1H), 7.35-7.5 (br m,3H), 7.72 (s,1H), 7.80 (m,3H). Diastereomeric purity: >99% de (HPLC).

1. customdoes not exceed −65° C
2. additionAfter the addition
3. customImmediately afterwards, the cooling bath is removed
4. stirringAfter 16 h of stirring at room temp.
5. extractionethyl acetate and the aqueous phase is extracted twice with ethyl acetate
6. dry with materialThe combined organic phases are dried over sodium sulphate
7. concentrationconcentrated
8. customThe residue was chromatographed over silica gel (mobile phase: dichloromethane)