3-Chloroaniline (I) was acylated with chloroacetyl chloride (II) in isopropyl acetate. The resulting chloroacetanilide (III) was condensed with ethanolamine (IV) to yield the (hydroxyethyl)glycinamide (V). Cyclization of (V) to produce the piperazinone (VI) was then effected by treatment with di-tert-butyl azodicarboxylate and tributylphosphine.
The mercaptoimidazole (IX) was prepared by condensation between 4-bromobenzylamine (VII), 1,3-dihydroxyacetone (VIII) and potassium thiocyanate. Oxidative desulfuration of (IX) with hydrogen peroxide in acidic medium yielded imidazole (X). The biphenyl derivative (XII) was obtained by Suzuki coupling of aryl bromide (X) with 4-(trifluoromethyl)benzeneboronic acid (XI). Subsequent oxidation of the alcohol group of (XII) under Swern conditions gave aldehyde (XIII). Finally, reductive coupling of aldehyde (XIII) with piperazinone (VI) in the presence of sodium triacetoxyborohydride furnished the title compound.