Synthesis of a Novel Hexa Cyclic Benzimidazo[1,2-c]indazolo-[2,3-a]quinazoline

Abstract

Two alternate synthetic routes are described for the synthesis of the hitherto unknown benzimidazo[1,2-c]indazolo[2,3-a]quinazoline (3). While dehydrative cyclisation of 2-[2-(2-azidobenzoylamino)-phenyl]benzimidazole (2) in polyphosphate ester gave 3 in low yield, very good yields were obtained in triethyl phosphite reductive cyclisation of 6-(2-nitrophenyl)benzimidazo[1,2-c]quinazolines (8).