反应详情

A solution of ethyl-o-toluate (41.2 g, 0.25 mole) in carbon tetrachloride (200 mL) was added dropwise to a stirring mixture of benzoyl peroxide (100 mg), carbon tetrachloride (200 mL) and NBS (44.5 g, 0.25 mole) at 0° C. The mixture was heated at reflux for 3.5 h under nitrogen, and allowed to cool to room temperature overnight. The precipitated succinimide was removed by filtration and the filter cake was washed with carbon tetrachloride. The combined filtrates were washed successively with 2 N NaOH (100 mL), and water (2×100 mL), and the solution was dried over anhydrous MgSO4, filtered (Celite), and evaporated under vacuum to yield the product as an oil. Drying under high vacuum overnight afforded 60.5 g (99%) of crude compound 5b; 1H NMR of the product showed the presence of ca. 15% of unreacted starting material. Since the mixture was not easily separable by chromatography or vacuum distillation it was used in the next step without further purification; 1H NMR (CDCl3) δ1.43 (t, J=7 Hz, 3H, CH2CH3), 4.41 (q, J=7 Hz, 2H, CH2CH3), 4.96 (s, 1H, CH2Br), 7.24 (m, 1H, ArH), 7.38 (m, 1H, ArH), 7.48 (m, 2H, ArH).

1. temperatureThe mixture was heated
2. temperatureat reflux for 3.5 h under nitrogen
3. customThe precipitated succinimide was removed by filtration
4. washthe filter cake was washed with carbon tetrachloride
5. washThe combined filtrates were washed successively with 2 N NaOH (100 mL), and water (2×100 mL)
6. dry with materialthe solution was dried over anhydrous MgSO4
7. filtrationfiltered (Celite)
8. customevaporated under vacuum