Acid hydrolysis of acetanilide (I) provided nitro aniline (II), which was further reduced to diamine (III) by catalytic hydrogenation over Pd/C. The 2-mercapto benzimidazole (IV) was then synthesized by condensation of phenylenediamine (III) with potassium ethyl xanthate. Alkylation of (IV) with the chloromethyl pyridine (V) produced the corresponding thioether adduct (VI). Finally, selective oxidation of the benzimidazolyl sulfur atom of (I) using m-chloroperbenzoic acid gave rise to the title sulfoxide.