To (R)-2-[(2-hydroxyethyl)(phenylmethyl)amino]-1-phenyl-1-ethanol hydrochloride (4.00 g, 12.7 mmol) produced in Example 8, distilled water (40 mL), toluene (40 mL) and 30 wt % aqueous solution of sodium hydroxide (1.70 g, 1.0 equivalent) were added. The mixture was stirred. After the organic layer and aqueous layer were separated, the organic layer was washed twice with distilled water (20 mL), then concentrated and dried under vacuum, to obtain 3.95 g of a concentrate. Ethyl acetate (13.22 g) and triethylamine (4.50 g, 3.5 equivalents) were added to the concentrate, and the mixture was cooled to 5° C. Methanesulfonyl chloride (4.66 g, 3.2 equivalents) was added dropwise thereto, and then allylamine (4.34 g, 6.0 equivalents) was added dropwise thereto. The mixture was stirred for 1 hour. The temperature of the mixture was raised to 25° C., and then the mixture was stirred for 4 hours. To the mixture, 10 wt % aqueous solution of sodium carbonate (21.54 g) was added. After the organic layer and aqueous layer were separated, the organic layer was washed twice with distilled water (20 mL). The organic layer was concentrated. The obtained concentrate was dissolved by adding ethyl acetate (20 mL). To the solution, 28 wt % hydrogen chloride solution in isopropanol (3.60 g, 2.2 equivalents) was added to precipitate crystals. The mixture was stirred at 25° C. for 1 hour. The crystals were separated by filtration under reduced pressure, washed with isopropanol (50 mL), and dried under vacuum, to obtain 2.96 g of the title compound as white crystals (yield: 71%, chemical purity: 98.4 area %). The retention time in the chemical purity analysis method was 7.9 min.
