This compound can be obtained in two different ways: 1) The reaction of 4,5,6-triaminopyrimidine (I) with refluxing SOCl2 gives 7-amino[1,2,5]thiadiazolo[3,4-d]pyrimidine (II). The reaction of 2-chloro-6-fluorobenzyl chloride (III) with ammonia in benzene affords 2-chloro-6-fluorobenzylamine (IV), which is condensed with (II) by heating at 150 C to yield 7-(2-chloro-6-fluorobenzyl)amino[1,2,5]thiadiazolo[3,4-d]pyrimidine (V). The formylation of (V) with formic acid in acetic anhydride gives 7-[N-formyl-N-(2-chloro-6-fluoro-benzyl)]amino[1,2,5]thiadiazolo[3,4-d]pyrimidine (VI), which by desulfuration with Raney-Ni in ethanol - water gives 4-[N-formyl-N-(2-chloro-6-fluorobenzyl)]amino-5,6-diaminopyrimidine (VII), product not isolated that dehydrates spontaneously to arprinocid.
2) By condensation of 2-chloro-6-fluorobenzyl chloride (III) with adenine (VIII) by means of Aliquat 336 in hexane - water, acetone or hexamethyl phosphoramide.