A solution of 3-phenyl-3-(2-pyrimidinyl)propenal (1.25 g) in tetrahydrofuran (125 cc) is added to 4-(4-methylbenzyl)piperazine (11.2 g). The solution is stirred and heated to a temperature in the region of 65° C. for 3 hours. After being coiled to a temperature in the region of 20° C., the reaction mixture is concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 40° C. The residue obtained is dissolved in ethyl acetate (10 cc) and the solution obtained is poured onto silica (25 g) contained in a column 1.5 cm in diameter. Elution is performed with a mixture (750 cc) of ethyl acetate and cyclohexane (50:50 by volume); the corresponding eluates are discarded. Elution is then performed with the same mixture (300 cc) and the corresponding eluate is concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 40° C. The oil obtained is dissolved in methyl ethyl ketone (20 cc). Oxalic acid (120 mg) dissolved in methyl ethyl ketone (20 cc) is added and the mixture is stirred for approximately 15 minutes at a temperature in the region of 20° C. The precipitate formed is separated by filtration and then recrystallized in boiling isopropyl alcohol (50 cc). 3-[4-(4-Methylbenzyl)-1-piperazinyl]-1-phenylpyrrolo[1,2-a]pyrimidine oxalate (300 mg), m.p. 205° C., is thereby obtained.
