C([O:4][C@H:5]([CH3:29])[CH2:6][CH2:7][CH2:8][CH2:9][N:10]1[C:19](=[O:20])[C:18]2[N:17]([CH3:21])[CH:16]=[N:15][C:14]=2[N:13]([CH2:22][CH2:23][CH2:24][CH2:25][CH2:26][C:27]#[N:28])[C:11]1=[O:12])(=O)C.Cl.O1CCOCC1>CO>[C:27]([CH2:26][CH2:25][CH2:24][CH2:23][CH2:22][N:13]1[C:14]2[N:15]=[CH:16][N:17]([CH3:21])[C:18]=2[C:19](=[O:20])[N:10]([CH2:9][CH2:8][CH2:7][CH2:6][C@H:5]([OH:4])[CH3:29])[C:11]1=[O:12])#[N:28]To a stirring solution of 0.37 g (R)-1-(5-acetoxyhexyl)-3-(5-cyanopentyl)-7-methylxanthine (0.92 mmol) in 20 ml methanol was added a solution of 4M hydrogen chloride in 70 ml 1,4-dioxane (2.77 mmol). The reaction was heated at reflux (80° C.) for five hours and then cooled to room temperature. The solvent was removed under reduced pressure and the resulting oil was treated with 25 ml saturated aqueous sodium bicarbonate solution and extracted three times with 25 ml dichloromethane. The combined extracts were washed 2× with 25 ml saturated aqueous sodium chloride solution dried over sodium sulfate, and concentrated under vacuum. The resulting residue was purified by flash chromatography eluting with 10% methanol-ethyl acetate to give 0.15 g (R)-3-(5-cyanopentyl)-1-(5-hydroxyhexyl)-7-methylxanthine (47% yield) as a viscous oil.
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