Acetonitrile → 2-[(5-Bromopentyl)oxy]benzenepropanoic acid methyl ester

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A mixture of 3.6 g (20 mmol) of 2-hydroxybenzenepropanoic acid methyl ester, 22 mL (160 mmol) of 1,5-dibromopentane, 8.73 g (63.3 mmol) of anhydrous granular potassium carbonate, and 145 mL of acetonitrile was stirred and refluxed for 24 hr. The resulting slurry was cooled and diluted with 300 mL of ether. The solids were removed by suction filtration and the filter cake was washed well with ether. The filtrate and washes were combined and concentrated in vacuo giving 38.59 g of a brown oil which was chromatographed on 200 g of silica gel, eluting with 49:1 and 19:1 hexane-ether. The fractions containing the desired product were combined and concentrated giving 5.86 g of an oil which was dissolved in 50 mL of methanol containing 0.2 g of p-toluenesulfonic acid monohydrate. The solution was stirred at room temperature for 17 hr and refluxed for 5 hr before being cooled and concentrated in vacuo. The residue was dissolved in ether and the solution was washed with saturated sodium bicarbonate solution and worked-up in the usual manner. The oily residue was chromatographed on 100 g of silica gel. Elution with 19:1 hexane-ether afforded 4.85 g (73.7%) of 2-[5-bromopentyl)oxy]benzenepropanoic acid methyl ester as a colorless oil.

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