Carbon tetrabromide → 4-Bromo-1-(bromomethyl)-2-methylbenzene

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Reaction Steps

After carbon tetrabromide (6.7 g, 20 mmol) and triphenylphosphine (5.2 g, 20 mmol) were added to a solution of (4-bromo-2-methylphenyl)methanol (3.7 g, 18.4 mmol) which was synthesized according to the method described in literature (Dawson, M. I., et al., J. Med. Chem., 1984, vol. 27, pp. 1516-1531) under ice-cooling, the mixture was stirred at room temperature for 1 hour. Hexane was added to the reaction mixture and the insolubles were removed by filtration. After the obtained filtrate was poured into water and the mixture was extracted with ethyl acetate, the organic layer was successively washed with water and a saturated aqueous NaCl solution and dried with anhydrous sodium sulfate. The residue obtained by removing the solvent under reduced pressure was purified by silica gel column chromatography (eluting solvent: n-hexane/ethyl acetate=10/0-10/1) to give a crudely purified 4-bromo-1-(bromomethyl)-2-methylbenzene. Potassium cyanide (1.3 g, 20 mmol) was added to a solution of crude 4-bromo-1-(bromomethyl)-2-methylbenzene obtained in the above in a mixture of ethanol-water (3:1, 40 ml), and the mixture was stirred at 60° C. for 1.5 hours. After the reaction mixture was poured into water and the mixture was extracted with ethyl acetate, the organic layer was washed with a saturated aqueous NaCl solution and dried with anhydrous sodium sulfate. The residue obtained by removing the solvent under reduced pressure was purified by silica gel column chromatography (eluting solvent: n-hexane/ethyl acetate=6/1-3/1) to give (4-bromo-2-methylphenyl)acetonitrile as a pale orange solid (2.4 g, two-step total yield: 63%).

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