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 his phenols 45-48, 54, 56, 57 with the appropriate dihalo compounds 1, 38 afforded the corresponding macrocyclic diamides 49-52 and 1,omega-bis-[quinoxalino(2,3-b)benzoxazepino-13-on-yl]alkanes 60, 61, respectively. (C) 2000 Elsevier Science Ltd. All rights reserved.