[CH3:1][N:2]1[C:10]2[N:9]=[CH:8][N:7]([CH2:11][CH2:12][CH3:13])[C:6]=2[C:5](=[O:14])[N:4]([CH2:15][CH2:16]C(=O)C)[C:3]1=[O:20].[C-:21]#[C-:22].[Li+].[Li+].[Cl-].[Ce+3].[Cl-].[Cl-].Cl.[O:30]1[CH2:35][CH2:34]OCC1>C1(C)C=CC=CC=1.O>[OH:30][C:35]([CH3:34])([C:21]#[CH:22])[CH2:16][CH2:15][N:4]1[C:5](=[O:14])[C:6]2[N:7]([CH2:11][CH2:12][CH3:13])[CH:8]=[N:9][C:10]=2[N:2]([CH3:1])[C:3]1=[O:20]A solution of 55.7 g (0.2 mol) of 3-methyl-1-(3-oxobutyl)-7-propylxanthine in a mixture of 200 ml each of dioxane and toluene was added dropwise in 45 minutes to a stirred suspension of 36.8 g (0.4 mol) of lithium acetylide as ethylenediamine complex and 98.6 g (0.4 mol) of anhydrous cerium(III) chloride in a mixture of 500 ml each of dry dioxane and toluene at 50° C. The mixture was then stirred at 50° C. for 7 hours, cooled and, after addition of cold water and acidification with 2 N hydrochloric acid, intensively extracted with chloroform, the extract was washed with water, dried over sodium sulfate and evaporated under reduced pressure, and the residue was purified by filtration through a silica gel column in the eluent chloroform/methanol (50:1), resulting in 35.0 g (58% of theory) of solid, which was recrystallized from ethanol with large losses.
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