Electrophilic sulfonation of 2,3-dihydrobenzofuran (I) using sulfur trioxide-dimethylformamide complex produced sulfonic acid (II), which was subsequently converted into the sulfonyl chloride (III) by chlorination with SOCl2. Reaction of sulfonyl chloride (III) with a solution of ammonia in cold dichloroethane gave rise to the sulfonamide (IV). This was subsequently condensed with 3,4-dichlophenyl isocyanate (V) to furnish the target sulfonyl urea