Coupling of N-Boc-D-formyltryptophan (I) with N-benzylglycine benzyl ester (II) by means of 2-chloro-1-methylpyridinium iodide (CMP) gave the protected dipeptide (III). Acid cleavage of the N-Boc group of (III) , followed by intramolecular cyclization under basic conditions, produced the diketopiperazine (IV). After basic hydrolysis of the N-formyl group of (IV), the resulting diketopiperazine (V) was reduced to piperazine (VI) using LiAlH4. Subsequent coupling of piperazine (VI) with 3,5-bis(trifluoromethyl)benzoic acid (VII) afforded amide (VIII). The N-benzyl group was then removed by transfer hydrogenolysis with ammonium formate and Pd/C, yielding piperazine (IX).

The piperazine (IX) was alkylated with benzyl bromoacetate (X) to give ester (XI), which was converted to carboxylic acid (XII) by catalytic hydrogenolysis of the benzyl ester group. Then, coupling of (XII) with 1-amino-4-methylpiperazine (XIII) produced the corresponding hydrazide. Finally, treatment with fumaric acid in EtOH generated the title fumarate salt.