Hydrochloric Acid → (R)-1-(3-chloropyrazin-2-yl)pyrrolidin-3-yl-[(R)-1-(naphthalen-1-yl)ethyl]amine dihydrochloride

To a solution of 162 mg of (R)-3-[(R)-1-(naphthalen-1-yl)ethylamino]pyrrolidine dihydrochloride and 79.0 mg of 2,3-dichloro-pyrazine in 5 ml of ethanol was added 345 mg of potassium carbonate, and the mixture was stirred under reflux for 16 hours. The reaction mixture was filtered, and the solvent was evaporated, and to the residue was added a saturated aqueous sodium bicarbonate solution and chloroform, and the liquids were separated. The organic layer was dried, and the solvent was evaporated, then, the residue was purified by NH silica gel column chromatography (hexane:ethyl acetate=97:3→80:20) and by silica gel chromatography (hexane:ethyl acetate=90:10→0:100) to obtain 64.0 mg of (R)-1-(3-chloropyrazin-2-yl)pyrrolidin-3-yl-[(R)-1-(naphthalen-1-yl)ethyl]amine (2) In 2 ml of chloroform was dissolved 64.0 mg of (R)-1-(3-chloropyrazin-2-yl)pyrrolidin-3-yl-[(R)-1-(naphthalen-1-yl)ethyl]amine, and 3 ml of a solution of 4M hydrochloric acid in dioxane was added to the mixture, and the resulting mixture was stirred. After the reaction mixture was concentrated under reduced pressure, diethyl ether was added to the residue, and the precipitates were collected by filtration, washed with diethyl ether, and dried to obtain 63.9 mg of (R)-1-(3-chloropyrazin-2-yl)pyrrolidin-3-yl-[(R)-1-(naphthalen-1-yl)ethyl]amine dihydrochloride (the following Table A2, Example 2.001).