The condensation between 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (I) and 2-hydrazinobenzoic acid (II) in refluxing HOAc afforded the pyrazole derivative (III). After conversion of (III) into the corresponding acid chloride (IV) by using SOCl2, treatment with ammonium hydroxide provided amide (V). Dehydration of amide (V) employing trichloroacetyl chloride and Et3N yielded nitrile (VI), which was reduced to the primary amine (VII) with NaBH4 and CoCl2. After protection of the amino group of (VII) as the N-Boc derivative (VIII), oxidative cleavage of the furan ring with KMnO4 produced the carboxylic acid (IX), which was further activated as the acid chloride (X) upon treatment with oxalyl chloride.

Coupling of acid chloride (X) with the biphenyl amine (XI) gave the corresponding amide (XII). The tert-butyl and Boc protecting groups of (XII) were finally cleaved by treatment with trifluoroacetic acid.