Synthesis of New Benzo-substituted Macrocyclic Ligands Containing Quinoxaline Subunits

The macrocyclic Schiff bases 20–25 were prepared by cyclocondensation of the bis aldehydes 12–15 with the appropriate diaminoalkanes 17–19. Reduction of the latter with NaBH4 afforded the corresponding azacrown ethers 27–30. Heating of the aldehydes 12–16 in refluxing acetic acid afforded the corresponding 2,3-bis(benzofuranyl)quinoxalines 33–37. Nucleophilic reaction of the bis phenols 45–48, 54, 56, 57 with the appropriate dihalo compounds 1, 38 afforded the corresponding macrocyclic diamides 49–52 and 1,ω-bis[quinoxalino(2,3-b)benzoxazepino-13-on-yl]alkanes 60, 61, respectively.