Synthesis of Some Ethyl 3-(Aryldiazenyl)-7-oxo-dihydropyrido [2, 3-f] quinoxaline-8-carboxylates

Abstract

Ethyl 7, 8-diamino-1-cyclopropyl-6-fluoro-4-oxo-1, 4-dihydroquinoline-3-carboxylate (6) and its free acid 7 are prepared by chemical reduction of the respective 7-azido-8-nitroquinoline 5. Consecutive nucleophilic addition and cyclocondensation reactions of 6 with α-acetyl-N-arylhydrazonoyl chlorides 8a–c in ethanol and triethylamine are site-selective and yield the corresponding 3-(aryldiazinyl)-2-methylpyrido [2, 3-f] quinoxalines 10a–c. Analytical and spectral (IR, MS, NMR) data of 6, 7, and 10a–c are in conformity with the assigned structures.