Sistalgin, Bracco, Italy,1974
20 g 4,4-diphenyl-cyclohexen-(2)-one, 10 g isopropylamine, and 50 ml tetrahydrofuran are agitated for 10 hours in a bomb tube at 200°C. Subsequently, the reaction mixture is cooled, and the tetrahydrofuran and theexcess isopropylamine are distilled off. The remaining Schiff base is dissolved in methanol and after the addition of 2 g platinum oxide, the base is hydrogenated at normal pressure and room temperature until a quantity of hydrogen corresponding to 2 mols has been absorbed.
The mixture is filtered off from the catalyst, made acidic with dilute hydrochloric acid, and the methanol is removed under vacuum. The remaining aqueous solution is made alkaline with solution of sodium hydroxide and extracted with ether. After drying and concentrating the ether extract, there is obtained 17 g 1-isopropylamino-4,4-diphenyl-cyclohexane, boiling point 164°C to 165°C/0.05 mm. The hydrochloride melts at 230°C.
