Ethanolamine → (R)-1-(5-acetoxyhexyl)-7-ethoxymethyl-8-(2-hydroxyethylamino)-3-methylxanthine

A mixture of (R)-1-(5-acetoxyhexyl)-8-bromo-7-ethoxymethyl-3-methylxanthine (4.45 g, 10.0 mmol) potassium carbonate (2.76 g, 20.0 mmol) and ethanolamine (1.22 g, 20.0 mmol) in dimethylsulfoxide (30 ml) was stirred at 80° C. for two hours. After cooling to room temperature, the reaction mixture was quenched by addition of saturated aqueous ammonium chloride solution (100 ml) and extracted with ethyl acetate (3×25 ml). The combined extracts were washed with saturated aqueous sodium chloride solution, with water, and dried over magnesium sulfate. Concentration under reduced pressure provided (R)-1-(5-acetoxyhexyl)-7-ethoxymethyl-8-(2-hydroxyethylamino)-3-methylxanthine (3.95 g, 93% yield) as a beige powder.