The condensation of 6-aminobenzothiazole (I) with ethyl 2-(methylsulfanyl)acetate (II) in the presence of tert-butyl hypochlorite produced the oxindole derivative (III). The methylsulfanyl group was then reductively removed using zinc in acetic acid to afford (IV). Reaction of (IV) with diethoxymethyl acetate in refluxing HOAc furnished the ethoxymethylene derivative (V). This was finally condensed with sulfapyridine (VI) to give the title compound.