Cu(II)–Glucose: Sustainable Catalyst for the Synthesis of Quinazolinones in a Biomass-Derived Solvent 2-MethylTHF and Application for the Synthesis of Diproqualone

Abstract

An efficient method for the synthesis of quinazolinones by a domino cross-coupling reaction of 2-halobenzoic acids and amidines is demonstrated for the first time using a copper–glucose combination as an inexpensive catalytic system in a biomass-derived green solvent 2-methylTHF. Here, glucose plays a dual role, both as a reducing agent generating the low-valent copper ions from cupric precursors and as a chelating agent of the generated low-valent copper species, thereby impeding their deactivation. A wide variety of quinazolinones were synthesized in good to excellent yields. Notably, the activation of less reactive 2-bromo/chlorobenzoic acids by the catalyst not only advocates the efficiency of the developed protocol but also the broad substrate scope. Moreover, the developed methodology was successfully applied to the synthesis of the drug molecule diproqualone. The UV–vis spectrophotometric titration study of cupric and cuprous salts with glucose showed evidence of glucose playing the role as a ligand, thus it may act as a stabilizing agent for the low valent copper species formed in the reaction. The use of inexpensive and air stable cupric salts along with glucose for the synthesis of quinazolinones in a green solvent makes this a benign and sustainable method.

A Bio‐Inspired Magnetically Recoverable Palladium Nanocatalyst for the Ullmann Coupling reaction of Aryl halides and Arylboronic acids In Aqueous Media

“…The Pd (II) X 2 so formed may get reduced by glucose to complete the cycle. During the reduction process, glucose gets oxidized to gluconic acid . Moreover, any chance of formation of acidic species from the halide ion remnants is not possible under the basic aqueous conditions.…”

Polydopamine: An Amine Oxidase Mimicking Sustainable Catalyst for the Synthesis of Nitrogen Heterocycles under Aqueous Conditions

“…Besides these, it also is a promising alternative to the conventional organic solvents, owing to which numerous research groups over the past decades have explored the prodigious potential of water as the reaction medium. , Thus, the development of water-compatible catalysts for the establishment of eco-friendly sustainable protocols are the need of the hour. Therefore, taking into account of the aforementioned advantages of metal-free protocols under aqueous conditions and the drawbacks of existing regime of catalysts, in continuation to our efforts to develop sustainable protocols using benign catalysts, − we herein report a biomimicking process wherein polydopamine is used as an organocatalyst for the oxidation of benzylic primary amines, alkyl amines and secondary amines aerobically. The formed intermediate imines are trapped by diamines (or) amides and aerobically oxidized to afford nitrogen heterocycles such as benzimidazoles, quinoxalines, and quinazolinones, as well as other heterocycles such as quinolines and indole via a domino/cascade process (Scheme ).…”

Recent Advancement in the Copper Mediated Synthesis of Heterocyclic Amides as Important Pharmaceutical and Agrochemicals

“…The catalytic system promoted the synthesis of a broad range of quinazolinones in moderate to high yields (See Figure 22). [64] …”