反应详情

To a solution of 2′-methyl-acetophenone (2.68 g, 20.0 mmol) in benzene (100 mL) was added ethylene glycol (2.0 mL, 35.9 mmol) followed by p-toluenesulfonic acid monohydrate (0.39 g, 2.10 mmol). The reaction flask was topped with a Dean-Stark trap, and the mixture was heated to reflux overnight. The mixture was cooled to room temperature, diluted with Et2O (100 mL), washed with saturated aqueous NaHCO3 (5×20 mL) and brine (3×25 mL), dried (MgSO4), and concentrated. The resultant colorless oil (3.6 g) was dissolved in CCl4 (50 mL) and to this solution was added N-bromosuccinimide (3.76 g, 21.1 mmol) followed by 1,1′-azobis(cyclo-hexanecarbonitrile) (0.98 g, 3.99 mmol). The resultant mixture was refluxed for 5 hours then cooled to room temperature, filtered through filter paper, and concentrated. Purification of the crude material by column chromatography on silica gel (20:1:hexanes-EtOAc) provided 4.09 g (80%) of 2-(2-bromomethyl-phenyl)-2-methyl-[1,3]dioxolane as a colorless oil. 1H NMR (CDCl3) δ 1.74 (s, 3H), 3.75-3.81 (m, 2H), 4.04-4.08 (m, 2H), 4.89 (s, 2H), 7.24-7.31 (m, 2H), 7.44-7.57 (m, 2H).

1. temperaturethe mixture was heated
2. temperatureto reflux overnight
3. washwashed with saturated aqueous NaHCO3 (5×20 mL) and brine (3×25 mL)
4. dry with materialdried (MgSO4)
5. concentrationconcentrated
6. dissolutionThe resultant colorless oil (3.6 g) was dissolved in CCl4 (50 mL) and to this solution
7. temperaturethen cooled to room temperature
8. filtrationfiltered
9. filtrationthrough filter paper
10. concentrationconcentrated
11. customPurification of the crude material by column chromatography on silica gel (20:1:hexanes-EtOAc)