Impact of Substituents on the Isatin Ring on the Reaction Between Isatins with Ortho-Phenylenediamine

Abstract

The reaction of different substituted isatins with ortho-phenylenediamine in acetic acid has been investigated. While electron-donor substituents on isatin shift the reaction toward classical 6H-indolo[2,3-b]quinoxaline ring closure, electron-withdrawing groups enhance the formation of 3-(2′-amino-5′-substituted)-quinoxaline-2(1H)-ones. The structures of all synthesized compounds were assigned by using infrared, mass, ¹H NMR, ¹³C NMR, ¹³C-¹H HSQC, and ¹³C-¹H heteronuclear multiple bond correlation (HMBC) spectroscopic data.

Keywords:

• 3-(2′-Amino-5′-substituted)-quinoxaline-2(1H)-one
• 6H-indolo[2,3-b]quinoxaline
• heterocycles
• NMR spectroscopy
• rearrangements

ACKNOWLEDGMENT

This research was supported by a grant from the research council of Tehran University of Medical Sciences.