反应详情

Anhydrous lithium bromide (10.6 g, 121.8 mmol) was added to a stirring mixture of 2 (5.95 g, 24.4 mmol) in acetone (50 mL) under argon, and the mixture was refluxed for 2 hours. After cooling, the acetone was evaporated under reduced pressure, and the residue was taken up in ether (50 mL), washed with water (50 mL), brine, dried (MgSO4), and the solvent was evaporated under reduced pressure. The residue was chromatographed (SiO2, heptane/ethyl acetate, 95:5) to give the dibromide 3 (5.36 g, 86%) as an orange liquid; Rf(heptane-ethyl acetate, 8:2), 0.82. δH (400 MHz; CDCl3): 3.6 (2H, m), 3.45 (2H, m), 2.85 (2H, m), 2.1 (2H, m), 1.7 (2H, m; δc(400 MHz; CDCl3): 39.70, 33.79, 23.95.

1. temperaturethe mixture was refluxed for 2 hours
2. temperatureAfter cooling
3. customthe acetone was evaporated under reduced pressure
4. washwashed with water (50 mL), brine
5. dry with materialdried (MgSO4)
6. customthe solvent was evaporated under reduced pressure
7. customThe residue was chromatographed (SiO2, heptane/ethyl acetate, 95:5)