Hydrochloric Acid → Duloxetine Hydrochloride

Participants

Reaction Conditions

Reaction Steps

Diisopropylethylamine (210 ml) is added to a solution of (S)-N,N-dimethyl-3-(1-naphthyloxy)-3-(2-thienyl)-propanamine (311 g; 99.6% ee) in toluene (1200 ml) and phenylchloroformate (150 ml) is then added at 60° C. After two hours of stirring at 80° C., the mixture is cooled down, shaken with a diluted solution of hydrochloric acid, water and a 2% solution of sodium hydrogencarbonate. The organic phase is dried with sodium sulfate and evaporated. The evaporation residue is dissolved in ethanol (300 ml) and a 5M solution of potassium hydroxide (400 ml) is added drop-wise under reflux. After two hours of refluxing, the mixture is evaporated to half the volume, diluted with water (1000 ml) and extracted with toluene (300 ml). The organic phase is dried with sodium sulfate and evaporated. The evaporation residue is dissolved in ethylmethylketone (300 ml) and concentrated HCl (1 mole), diluted with ethylmethylketone (300 ml), is added drop-wise at 0° C.; then the mixture is stirred for two hours. The precipitated crystals are then sucked off. Yield: 250 g (75%), m.p.: 167-169° C. Recrystallization from ethylmethylketone affords colorless crystalline duloxetine hydrochloride, m.p. 170.5-171.5° C. Optical purity: 99.9% ee (CE), chemical purity: 99.9% (HPLC).

Provenance & Evidence