The general procedure for the synthesis of 7-((1,3-dioxolan-2-yl)methyl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione from 2-bromomethyl-1,3-dioxolane and 1,3-dimethyl-1H-purine-2,6(3H,9H)-dione was carried out as follows: to a reactor, 13 kg (72.16 mol) of 1,3- dimethyl-1H-purine-2,6(3H,9H)-dione (theophylline), 8 L of acetone, 5.77 kg (144.32 mol) of sodium hydroxide and 0.7 kg (2.16 mol) of tetrabutyl ammonium bromide. After stirring for 10 min, 14.47 kg (86.64 mmol) of 2-bromomethyl-1,3-dioxolane (bromoacetaldehyde acetal) was added. The mixture was refluxed for 6.3 h and the progress of the reaction was monitored by thin-layer chromatography (unfolding reagent ratio acetone: dichloromethane = 3:1). Upon completion of the reaction, the solvent was removed by distillation under reduced pressure, washed three times with saturated sodium chloride solution, and the residue was recrystallized from anhydrous ethanol to give 17.28 kg (64.98 mol) of 7-((1,3-dioxolan-2-yl)methyl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione (doxophyllotoxin) in 90% yield and purity over 98.5%.
