Rapid, efficient and eco-friendly procedure for the synthesis of quinoxalines under solvent-free conditions using sulfated polyborate as a recyclable catalyst

Abstract

An efficient and inexpensive sulfated polyborate catalyst was applied for the rapid synthesis of quinoxaline derivatives from various substituted o-phenylenediamines and 1,2-diketones/α-hydroxy ketones using sulfated polyborate is described. The catalyst has the advantage of Lewis as well as Bronsted acidity and recyclability without significant loss in catalytic activity. The key advantages of the present method are high yields, short reaction times, solvent-free condition, easy workup, and ability to tolerate a variety of functional groups, which give economical as well as ecological rewards.

Green Hydrothermal Synthesis of Fluorescent 2,3‐Diarylquinoxalines and Large‐Scale Computational Comparison to Existing Alternatives

“…Quinoxalines are widely used in medicine, for example, as antibacterial, antifungal, or anticancer agents, [3–5] and also as building blocks in advanced materials [6–8] . Various syntheses of quinoxalines have been reported, most employing 1,2‐diamines in combination with different carbonyl compounds (Scheme 1B), that is, mainly diketones or α‐substituted carbonyl compounds (e. g., α‐hydroxyketones, [9–12] α‐bromoketones [13] or α‐oximeketones [14] ), and the transformations require the presence of oxidizing agents. The vast majority of reported syntheses of quinoxalines use traditional organic solvents and require reaction times ( t r ) of several hours.…”

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

“…Broad functional group tolerance, mild reaction condition, recoverability, and reusability of the catalyst without affecting the outcome of the reaction, are some of the advantages of all of the developed strategies (Table 1). [64][65][66][67][68][69][70] Although their emergence in organic chemistry in only about the last decades, ultrasound irradiation has been considered as a powerful alternative energy source for the construction of value-added compounds to make them sustainable from the perspective of green chemistry. 71 Scheme 2 One-pot reduction and subsequent tandem condensation to access diverse quinoxaline derivatives 7.…”

Expeditious and efficient synthesis of Strecker’s α-aminonitriles catalyzed by sulfated polyborate

“…[47][48][49][50][51][52] Its easy preparation, mild acidity, eco-friendliness, and reusability have encouraged us to investigate its potential to catalyze many other useful organic transformations. Therefore, inspired by our previous finding, herein we report a rapid, efficient and green method for synthesis of α-aminonitriles via Strecker reaction using aldehyde, amine, and TMSCN in the presence of a sulfated polyborate as a recyclable catalyst under solvent-free conditions.…”