4-Bromobenzenesulfonyl chloride (I) was condensed with aminoisoxazole (II) in pyridine to afford sulfonamide (III). Subsequent Suzuki coupling of (III) to 4-tolylboronic acid (IV) under palladium catalysis provided biphenylsulfonamide (V), which was finally brominated with N-bromosuccinimide in cold CH2Cl2 to furnish the target bromoisoxazole.

Suzuki coupling of 4-tolylboronic acid (I) with 2-bromothiophene (II) under palladium catalysis provided tolylthiophene (III). Subsequent chlorosulfonation of (III) with chlorosulfonic acid in the presence of PCl5 and POCl3 afforded sulfonyl chloride (IV), which was finally condensed with the aminoisoxazole (V) using NaH in THF to furnish the target sulfonamide.