Synthesis of novel fluorescent acridono- and thioacridono-18-crown-6 ligands

Novel fluorescent 18-crown-6 type ligands containing acridono and thioacridono units were synthesised. The acridono ligand was prepared by the oxidation of its acridino analogue, and also by the cyclisation of 4,5-dihydroxyacridine-9(10H)-one and tetraethylene glycol di-p-tosylate in the presence of K2CO3. The acridono macrocycle was converted to the thioacridono ligand using Lawessonsʹs Reagent. The synthesis of several precursors leading to the preparation of an acridono-18-crown-6 fluorophore was also performed. These precursors can also be very useful building blocks for acridine, acridone and thioacridone derivatives of chemotherapeutical importance.