pyrimido 2 1 f purine 2 4 8 1h 3h 9h trione in 10 5 liters of dry 1 4 dioxane add 68 1 g 3 14 moles of lithium borohydride in portions maintain the reaction temperature at 20 u00b0 25 u00b0 c by controlling the rate of addition and by use of a cooling bath as needed stir the mixture at room temperature for 0 5 hour then reflux for 18 hours remove solvent under reduced pressure allow the residue to cool then add 4 5 liters of chloroform to the resultant mixture cautiously add dropwise 1 1 liters of water stir the mixture at room temperature until two clear phases result add 3n hydrochloric acid portionwise to bring the ph to 4 5 separate the layers and extract the aqueous phase with two 1 1 liter portions of chloroform wash the combined extracts with three 1 1 liter volumes of water and dry over anhydrous sodium sulfate filter the drying agent and remove volatiles from the filtrate under reduced pressure crystallize the residue from methanol ethyl acetate to obtain title compound i as a solid with m p 176 u00b0 182 u00b0 c to a suspension of 75 g 0 221 mole of i in 4 2 liters of ethanol anhydrous 2b add 12 g 0 221 mole of sodium methoxide portionwise during about twenty minutes to the resultant mixture add 33 g 0 221 mole of 1 bromo 3 methyl 2 butene.