An environmentally friendly, cost effective synthesis of quinoxalines: the influence of microwave reaction conditions

Substrate-Controlled Product Divergence in Iron(III)-Catalyzed Reactions of Propargylic Alcohols: Easy Access to Spiro-indenyl 1,4-Benzoxazines and 2-(2,2-Diarylvinyl)quinoxalines

We report herein unprecedented cascade reactions of O-propargyl-N-tosyl-amino phenols with 10 mol% FeCl₃ in DCE at room temperature for 0.67-3 h to form spiro-indenyl 1,4-benzoxazines with 38-89 % yield. Replacing the substrates' oxygen atom by a N-tosylimine group followed by treatment with the same catalyst and solvent at 80 °C produced 2-(2,2-diarylvinyl)quinoxalines in 12-20 h with up to 62 % yield. Mechanistic understanding provided an insight into the transformations. The use of simple substrates and an environmentally benign low-cost catalyst, broad substrate scope and tolerance of diverse functional groups makes the methodology inherently attractive.

An overview of quinoxaline synthesis by green methods: recent reports

Quinoxalines and their derivatives belong to an important class of bicyclic aromatic heterocyclic system, also known as benzopyrazines, containing a benzene ring and a pyrazine ring. They have attracted considerable attention over the years due to their potential biological and pharmaceutical properties. A wide range of synthetic strategies is reported in this significant area of research. The present review showcases recent research advances in the synthesis of quinoxaline derivatives following environmentally benign approaches.

Organocatalytic Combinatorial Synthesis of Quinazoline, Quinoxaline and Bis(indolyl)methanes

AIMS AND OBJECTIVE

An efficient and practical procedure for the synthesis of heterocyclic compounds such as quinazolines, quinoxalines and bis(indolyl)methanes was developed using 3,5-bis(trifluoromethyl) phenyl ammonium hexafluorophosphate (BFPHP) as a novel organocatalyst.

MATERIALS AND METHODS

All of the obtained products are known compounds and identified by IR, 1HNMR, 13CNMR and melting points.

RESULT

Various products were obtained in good to excellent yields under reaction conditions.

CONCLUSION

The BFPHP organocatalyst demonstrates a novel class of non-asymmetric organocatalysts, which has gained much attention in green chemistry.

PIDA-mediated intramolecular oxidative C-N bond formation for the direct synthesis of quinoxalines from enaminones

A intramolecular oxidative C(sp2)-N bond formation mediated by hypervalent iodine(iii) to obtain quinoxalines from readily available N-(2-acetaminophenyl)enaminones was developed. A tandem process involving PIDA-mediated intramolecular condensation cyclization and a subsequent elimination was postulated, which was highly efficient and metal-free under mild conditions. Moreover, flexible structural modifications of quinoxalines bearing carbonyl groups are of interest for further transformations as building blocks in organic synthesis.

An insight into medicinal chemistry of anticancer quinoxalines

Quinoxalines are benzopyrazines containing benzene and pyrazine rings fused together. In the recent past, quinoxalines have attracted Medicinal Chemists considerably for their syntheses and chemistry due to their distinct pharmacological activities. Diverse synthetic protocols have been developed via multicomponent reactions, single pot synthesis and combinatorial approach using efficient catalysts, reagents, and nano-composites etc. Further, the versatility of the quinoxaline core and its reasonable chemical simplicity devise it extremely promising source of bioactive compounds. Therefore, a wide variety of bioactive quinoxalines has been realised as antitumour, antifungal, anti-inflammatory, antimicrobial, and antiviral agents. Already, a few of them are clinical drugs while many more are under various phases of clinical trials. Present review focuses on chemistry and pharmacology (both efficacy and safety) of quinoxalines and also provides some insight in to their structure-activity relationship.

Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes

Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.

Facile, eco-friendly, catalyst-free synthesis of polyfunctionalized quinoxalines

A novel, facile and eco-friendly synthesis of quinoxalines from [Formula: see text] and 1,2-diamines was developed. An attractive feature of this protocol is that the desired products could be generated efficiently in water and without any catalyst, which is in accordance with the aim of green chemistry. A plausible mechanism has been proposed.

Copper-catalyzed aerobic oxidative coupling of o-phenylenediamines with 2-aryl/heteroarylethylamines: direct access to construct quinoxalines

A versatile method for synthesis of quinoxalines by Cu-catalyzed oxidative coupling of o-phenylenediamines with 2-arylethylamines is presented.

One-step approach for the synthesis of functionalized quinoxalines mediated by T3P®–DMSO or T3P® via a tandem oxidation–condensation or condensation reaction

An easy and efficient (T3P®)–DMSO or T3P® mediated oxidation–condensation or condensation reaction for the synthesis of quinoxalines from the different arrays of condensing partners and ortho-phenylene diamines (o-PDs) in one step has been reported.

An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination could be detected in the products by AAS measurements, pointing to the excellent activity and stability of the Co nanomaterial.

Recent developments in one-pot tandem oxidation process coupling reactions

The recent additions to the tandem oxidation process (TOP) research area are reviewed.