To a stirring suspension of 8-bromo-7-ethoxymethyl-3-methylxanthine (1.52 g, 5.0 mmol) in anhydrous dimethylsulfoxide (20 ml) was added sodium hydride (144 mg, 6.0 mmol). The mixture was stirred at room temperature for 30 min and then (R)-5-acetoxy-1-chlorohexane (983 mg, 5.5 mmol) was added and the mixture was stirred at 70-75° C. The (R) 5-acetoxy-1-chlorohexane was prepared according to methods described in U.S. Pat. No. 5,629,423 issued to Klein, J. P., Leigh, A. J., Michnick, J., Kumar, A. M., Underiner, G. E., on May 13, 1997, which is incorporated herein by reference. After 12 hours, the mixture was cooled to room temperature, quenched with saturated aqueous sodium chloride solution (100 ml) and extracted with ethyl acetate (3×50 ml). The combined extracts were washed with water (2×25 ml), with saturated aqueous sodium chloride solution (25 ml) and dried over magnesium sulfate. After evaporation of the solvent under reduced pressure, the product was purified by flash chromatography over silica gel eluting with ethyl acetate to provide (R)-1-(5-acetoxyhexyl)-8-bromo-7-ethoxymethyl-3-methylxanthine (1.83 g, 82% yield) as a beige solid.
