Ethylene Glycol → 1,3-Dioxolane, 2-[2-(bromomethyl)phenyl]-2-methyl-

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Reaction Steps

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).

Provenance & Evidence