7-Benzyl-3,8-dimethylxanthine (500 mg, 1.85 mmol) was added to a suspension of sodium hydride (50.5 mg) in anhydrous dimethylsulfoxide (20 ml). After stirring for 30 minutes, (R) 5-acetoxy-1-chlorohexane (357 mg) was added and the mixture was warmed to 70-80° C. for 12 hours. 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. After cooling to room temperature, the reaction was quenched by the addition of water (50 ml) and extracted with ethyl acetate (3×75 ml). The combined extracts were washed with water (2×50 ml), washed with saturated aqueous sodium chloride solution (50 ml), dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with ethyl acetate to give (R)-1-(5-acetoxyhexyl)-7-benzyl-3,8-dimethylxanthine (638 mg).
