19411-80-4

35271-74-0

The general procedure for the synthesis of 3-(4-chlorophenyl)glutaric acid using baclofen impurity 9 as starting material: the intermediate Π was dissolved in 420 mL of a 30 N aqueous solution of potassium hydroxide and the reaction was stirred for 2 hr at 85-90 °C. The reaction process was monitored by thin layer chromatography (TLC) and the unfolding agent was a mixture of ethyl acetate and petroleum ether (2:3, v/v). After completion of the reaction, the reaction mixture was cooled to room temperature and 400 mL of dichloromethane and 500 mL of deionized water were added sequentially. After stirring for 20 min, the organic and aqueous layers were separated and the organic layer was discarded. The aqueous layer was acidified to pH 1-2 with 6 M hydrochloric acid and the precipitated solid was subsequently filtered. The solid was washed with deionized water and dried under vacuum at 55-60°C for 5 h to give 157 g of white solid intermediate in 86.4% yield. The melting point of the intermediate was 166.5~167.3 °C.