A Simple and Efficient Method for the Synthesis of Benzo[3,4-a]Phenazin-5-Ols and Benzo[f]Pyrido[b]Quinoxalin-5-ol Derivatives Using Trisodium Citrate as an Efficient Organo-Catalyst at Room Temperature

Abstract

A simple, convenient, efficient and environmentally benign method has been developed for the synthesis of benzo[3,4-a]phenazin-5-ol as well as benzo[f]pyrido[2,3-b]quinoxalin-5-ol derivatives via the condensation of lawsoneand o-phenylenediamines or pyridine-2,3-diamines respectively by using a catalytic amount of trisodium citrate as an efficient, commercially available and low cost organo-catalyst in aqueous ethanol at room temperature. Mild reaction conditions, use of metal-free organocatalyst, nontoxic solvent, energy efficiency, no column chromatographic separation, gram scale production and reusability of the catalyst containing solvent media are some of the notable advantages of our developed protocol.

GRAPHICAL ABSTRACT

Keywords:

• Trisodium citrate
• benzo[a]phenazin-5-ol
• green synthesis
• lawsone
• organocatalysis
• room temperature reaction

Acknowledgements

Dr. B. Banerjee is thankful to the Akal University, Talwandi Sabo, Punjab, India and the Kalgidhar Trust, Baru Sahib, Himachal Pradesh, India for the support. Authors are grateful to AMRC, IIT Mandi, Himachal Pradesh, India for the spectral measurements such as ¹H and ¹³C NMR, HRMS and single X-ray crystal data.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supporting information summary

Scanned spectra including ¹H-NMR, ¹³C-NMR and HRMS of all the synthesized scaffolds are supplemented in supporting information.