Abstract
Oxoisoindolium hexachloroantimonate 1a was reacted with different nitriles to afford 2-azoniaallene salts. These underwent cyclization on heating, furnishing tetracyclic compounds 2a, b. Oxoisoindolo[2,1-a]quinazolinium hexachloroantimonate 3 reacted with p-toluidine to afford the corresponding salt 4. This was neutralized with sodium carbonate to give the corresponding free base 5. Isoindolo[2,1-a]quinazoline derivative 6 was prepared by treatment of 3 with benzohydrazide in dichloroethane. Reaction of the extremely sensitive salt of oxoisoindolium 1 with aminothiazole derivative 7 afforded the formal salts of 2-azoniaallene 8. Neutralization of these afforded the corresponding free base 9. The structures of the synthesized compounds were confirmed by IR, H-1 NMR, C-13 NMR, and mass spectroscopy. The free base compounds were screened for antimicrobial activity.