合成路线1

Conversion of 4-fluoro-3-nitroaniline (I) into the N-methyl derivative (III) was achieved via formation of the corresponding p-toluenesulfonamide (II), which was further N-alkylated with dimethyl sulfate in the presence of NaOH, followed by sulfonamide hydrolysis with concentrated sulfuric acid. Displacement of the fluoride group of (III) with phenethylamine (IV) in hot NMP gave rise to the p-phenylenediamine (V). After selective protection of the methylamino group of (V) as the N-Boc derivative (VI), the nitro group was reduced to amine (VII) by catalytic hydrogenation over Pd/C. Condensation of (VII) with benzoyl isothiocyanate to yield (VIII), and subsequent cyclization in the presence of EDC, produced the benzimidazole (IX). Acidic cleavage of the Boc protecting group of (IX) gave amine (X). This was finally condensed with isopropyl isocyanate to furnish the title urea.