Scheme 6.

Synthesis of 3′′,3′′′-[6′-(4-sulfamoylphenylamino)-1′,3′,5′-triazine-2′,4′-diyl]-bis(azanediyl)dipropanoic acid 4. Reagents and conditions: 4-(4′,6′-dichloro-1′,3′,5′-triazin-2′-ylamino)-benzene-sulfonamide 1, β-alanine, Na₂CO₃, and H₂O were refluxed for 24 h. Product yield: 95%.