To a solution of anhydrous calcium chloride (1.86 g, 16.3 mmol) in ethanol (32 mL) were added sodium borohydride (1.27 g, 33.6 mmol) and ethanol (5 mL) at −10° C., and the mixture was stirred at −10° C. for 30 min. To the reaction mixture were added dropwise a solution of ethyl (3S)-3-hydroxy-3-{6-[(methylamino)carbonyl]-2-naphthyl}-3-(1-tosyl-1H-imidazol-4-yl)propanoate (2.5 g, 5.6 mmol) in tetrahydrofuran (73 mL)/ethanol (10 mL), and tetrahydrofuran (5 mL) at −10° C. The obtained reaction mixture was stirred at 5° C. for 6 hr, and to the obtained reaction mixture were added dropwise water (100 mL), 1 mol/L hydrochloric acid (40 mL) and ethyl acetate (200 mL) at 10° C. or below, and the mixture was stirred. To the separated organic layer was added 0.2 mol/L hydrochloric acid (14 mL) at 5° C., and the mixture was stirred. The reaction mixture was adjusted to pH 7.5 with 0.5 mol/L aqueous sodium hydroxide solution at 5° C. To the separated organic layer was added again 0.2 mol/L hydrochloric acid (14 mL) at 5° C., and the mixture was stirred. The reaction mixture was adjusted to pH 7.5 with 0.5 mol/L aqueous sodium hydroxide solution at 5° C. To the separated organic layer was added water (10 mL), and the mixture was adjusted to pH 9.5 with 0.5 mol/L aqueous sodium hydroxide solution. To the separated organic layer was added water (120 mL), and the mixture was heated to 60° C., and stirred for 3 hr. The separated organic layer was concentrated at 60° C. under reduced pressure to give 6-[(1S)-1,3-dihydroxy-1-(1-tosyl-1H-imidazol-4-yl)propyl]-N-methyl-2-naphthamide (2.9 g, 6.1 mmol).
