Potassium Hydroxide → Brofaromine

Participants

Reaction Steps

7.6 g of 4-(7-bromo-5-methoxy-benzofuran-2-yl)-1-ethoxycarbonyl-piperidine are dissolved in 80 ml of ethylene glycol. After the addition of 19.4 g of 86% potassium hydroxide, the resulting cloudy solution is heated at 160° with vigorous stirring for 18 hours. The reaction mixture is cooled to 100°, diluted with 80 ml of toluene, and cooled further to 20°. The reaction solution is extracted twice with 1000 ml of water each time and then four times with 200 ml of a 10% solution of methanesulfonic acid in water each time. The resulting solution in methanesulfonic acid is adjusted to pH 12 by the addition of 30% sodium hydroxide solution and extracted by shaking with 1000 ml of chloroform. The chloroform solution is dried over sodium sulfate, filtered and concentrated by evaporation. Crystallisation from ethyl acetate yields 4-(7-bromo-5-methoxybenzofuran-2-yl)-piperidine having a melting point of 149°-152°. There is obtained from the base by treatment with methanolic hydrochloric acid and recrystallisation from methanol/ether 4-(7-bromo-5-methoxy-benzofuran-2-yl)-piperidine-hydrochloride having a melting point of 242°-243°.

Provenance & Evidence