1,3-Dibromopropane → 4(3-Bromopropylthio)-gamma-oxobenzenebutanoic acid

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Reaction Conditions

Reaction Steps

A mixture of the product of Example 1, Step E (5 g), 1,3-dibromopropane (20 g) and K2CO3 (10 g) was refluxed in methylethylketone (100 ml) for 20 hours. The cooled reaction mixture was filtered, the solvent evaporated and the residue purified by chromatography over silica gel. The resulting ester of the title compound was hydrolyzed by dissolving in a mixture of 25 ml of methanol and 15 ml of 1N NaOH and stirring at 25° C. for 4 hours. The reaction mixture was diluted with 100 ml of water, acidified with citric acid and extracted with 2×100 ml of EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and evaporated to yield the title compound which was sufficiently pure for use in the next step, m.p. 91°-94°.

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