The common intermediate (IV) was obtained by coupling of 4-formylbenzoic acid (I) with methyl 2-L-amino-5-phthalimidopentanoate.HCl (III) via the mixed anhydride (II).

The first synthetic method started from 2,4-diamino-6-(hydroxymethyl)-pteridine (V). Conversion of (V) into the corresponding bromide (VI) was achieved by treatment with triphenylphosphine dibromide. Ylide (VII) was then prepared by reaction of bromide (VI) with triphenylphosphine, followed by deprotonation using potassium tert-butoxide. Wittig reaction between ylide (VII) and aldehyde (IV) produced the olefin (VIII), assumed to be a mixture of geometric isomers. Catalytic hydrogenation of olefin (VIII), followed by reoxidation of the pteridine ring with H2O2, yielded (IX). Finally, hydrolysis of (IX) with NaOH gave rise to the title compound.

An alternative route involved a Wittig reaction between aldehyde (IV) and ylide (XI), generated from 2-amino-3-cyanopyrazin-5-ylmethyltriphenylphosphonium chloride (X). The resulting adduct (XII) was then cyclized and partly hydrolyzed to pteridine (XIV) upon refluxing with guanidine (XIII) in MeOH. Catalytic hydrogenation and further reoxidation of (XIV) yielded (XV). The methyl ester group of (XV) was finally hydrolyzed by treatment with NaOH in DMSO.

In the third synthetic route, 3-methoxy-1-propyne (XVI) was isomerized to 1-methoxyallene (XVII) by means of potassium tert-butoxide and then treated with HCl to give 1-chloro-4-methoxy-2-butene (XVIII). Alkylation of the dilithio derivative of p-toluic acid (XIX) with chloride (XVIII) yielded (XX). Bromination of the enol ether (XX), followed by acid hydrolysis furnished bromo aldehyde (XXI). This was cyclized with tetraaminopyrimidine (XXII), affording the dihydropteridine (XXIII), which was subsequently dehydrogenated to pteridine (XXIV) employing KI3. The carboxylic acid group of (XXIV) was activated as the mixed anhydride (XXV) with isobutyl chloroformate and then coupled to aminoester (III), yielding amide (IX).