Scheme 1

Scheme of the preparation of Schiff's bases from sulfamethoxazole. (1) 4-[(2-Hydroxy-benzylidene)-amino]-N-(5-methyl-isoxazol-3-yl)-benzene sulfonamide. (2) N-(5-Methyl-isoxazol-3-yl)-4-[(4-nitroox-benzylidene)-amino]-benzene sulfonamide. (3) 4-[(4-Dimethylamino-benzylidene)-amino]-N-(5-methyl-isoxazol-3-yl)-benzene sulfonamide. (4) 4-[(4-Bromo-benzylidene)-amino]-N-(5-methyl-isoxazol-3-yl)-benzene sulfonamide. (5) (N-(5-Methyl-isoxazol-3-yl)-4-[(3-nitro-benzylidene)-amino]-benzene sulfonamide.