Pyrimidopyrimidine tetraone (I) was converted to the disodium salt (II), which was then treated with PCl5 in refluxing POCl3 to provide the tetrachloro pyrimidopyrimidine (III). Displacement of the more reactive 4- and 8-chlorine atoms of (III) by 4-methoxybenzylamine (IV) in THF at room temperature gave the 4,8-di(4-methoxybenzylamino) derivative (V). Finally, the remainig chlorine atoms of (V) were displaced by diethanolamine (VI) at 110 C, yielding the title compound.

Condensation of 3,4-dimethoxybenzylamine (I) with 3,4-dimethoxybenzaldehyde (II) afforded imine (III), that was subsequently reduced to amine (IV) by means of NaBH4. Reaction of (V) with 2,4,6,8-tetrachloropyridopyrimidine (V) in THF at room temperature produced the 4,8-diamino derivative (VI). The remaining 2- and 6-chloro groups of (VI) were then displaced by aminoalcohol (VII) in boiling THF to furnish adduct (VIII). Finally, selective cleavage of two dimethoxybenzyl groups using trifluoroacetic acid gave rise to the title compound.