To an ice-cooled solution of (2S,3S)-2-benzyloxy-5-(1-naphthyl)pentan-3-ol (obtained in Preparation 26) (7.43 g) in dichloromethane (100 ml) was added methanesulfonyl chloride (2.15 ml) followed by triethylamine (3.88 ml). The mixture was stirred at 4° C. for 40 min. After being diluted with dichloromethane, the mixture was washed with water and brine, dried and concentrated in vacuo to give (2S,3S)-2-benzyloxy-5-(1-naphthyl)-3-pentyl methanesulfonate (9.92 g, 107.4%) as an oil. The product was used directly in the next step without further purification.
