Issue 59, 2021

Recent advances in the transition-metal-free synthesis of quinoxalines

Abstract

Quinoxalines, also known as benzo[a]pyrazines, constitute an important class of nitrogen-containing heterocyclic compounds as a result of their widespread prevalence in natural products, biologically active synthetic drug candidates, and optoelectronic materials. Owing to their importance and chemists' ever-increasing imagination of new transformations of these products, tremendous efforts have been dedicated to finding more efficient approaches toward the synthesis of quinoxaline rings. The last decades have witnessed a marvellous outburst in modifying organic synthetic methods to create them sustainable for the betterment of our environment. The exploitation of transition-metal-free catalysis in organic synthesis leads to a new frontier to access biologically active heterocycles and provides an alternative method from the perspective of green and sustainable chemistry. Despite notable developments achieved in transition-metal catalyzed synthesis, the high cost involved in the preparation of the catalyst, toxicity, and difficulty in removing it from the final products constitute disadvantageous effects on the atom economy and eco-friendly nature of the transformation. In this review article, we have summarized the recent progress achieved in the synthesis of quinoxalines under transition-metal-free conditions and cover the reports from 2015 to date. This aspect is presented alongside the mechanistic rationalization and limitations of the reaction methodologies. The scopes of future developments are also highlighted.

Graphical abstract: Recent advances in the transition-metal-free synthesis of quinoxalines

Article information

Article type
Review Article
Submitted
16 Sep 2021
Accepted
30 Oct 2021
First published
19 Nov 2021
This article is Open Access
Creative Commons BY license

RSC Adv., 2021,11, 37325-37353

Recent advances in the transition-metal-free synthesis of quinoxalines

B. Borah and L. R. Chowhan, RSC Adv., 2021, 11, 37325 DOI: 10.1039/D1RA06942J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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