To 14 ml of a methanol solution of sodium methoxide (1M solution) are added 2.04 g of 6-mercaptohexanol and 0.24 g of sodium borohydride, to which a THF (20 ml) solution containing 2.18 g of 2-methoxy-3-octadecyloxypropyl methanesulfonate is added dropwise under nitrogen streams with stirring. The mixture is stirred at room temperature for 20 hours and then at 40° C. for 1 hour. After the addition of water, the mixture is extracted with ethyl acetate. The extracted layer is washed with water, dried and concentrated under reduced pressures to obtain an oily product. Purification of the oily product by silica gel column chromatography gives 2.31 g of the captioned compound.
