Microwave activated synthesis of 2-aryl-quinazolin-4(3H)ones

Straightforward synthesis of quinazolin-4(3H)-ones via visible light-induced condensation cyclization

A green, simple and efficient method is developed for the synthesis of quinazolin-4(3H)-ones via visible light-induced condensation cyclization of 2-aminobenzamides and aldehydes under visible light irradiation. The reaction proceeds using fluorescein as a photocatalyst in the presence of TBHP without the need for a metal catalyst. In addition, this reaction tolerates a broad scope of substrates and could afford a variety of desirable products in good to excellent yields. Thus, the present synthetic method provides a straightforward strategy for the synthesis of quinazolin-4(3H)-ones.

Visible light was used as a readily available and renewable clean energy source for the green and metal catalyst free synthesis of quinazolin-4(3H)-ones. High and excellent yields of the desired products were obtained with good functional group tolerance.

Transition Metal-free Approach for the Synthesis of 2-substituted Quinazolin-4(3H)-one via Anhydrous Magnesium Perchlorate

Background:

A convenient and efficient methodology for the synthesis of quinazolin- 4(3H)-ones from simple and readily available 2-amino benzamides and aromatic aldehydes in ethanol using Magnesium perchlorate are being reported in the present study. Good to excellent isolated yields (68-95%) of the corresponding 2-substituted quinazolinones were obtained under mild reaction conditions with excellent functional group tolerance. The affordability of the catalyst, the wide availability of the starting materials, transition metal free synthesis and the simplicity of the procedure renders the present methodology useful in organic synthesis.

Objective:

A maneuver methodology developed for the synthesis of quinazolin-4(3H)-ones via using Magnesium perchlorate from 2-amino benzamides and aromatic aldehydes in ethanol.

Methods:

10% mol anhydrous Magnesium perchlorate in presence of ethanol give to simply rapid formation of Quinazolin-4(3H)-ones from 1 mole of 2-amino benzamides and 1 mole of aromatic aldehydes.

Results:

Screening results of Anti-leishmanial showed that out of the synthesized series of 12 compounds, compounds 3c, 3d, 3g, 3h and 3i showed significant antileishmanial activities (L. donavani) with IC50 values 8.39, 9.37, 9.43, 7.1 and 8.7 μM.

Conclusion:

In summary, we have developed convenient synthesis of quinazolin-4(3H)-one, from simple and easily available precursor employing anhydrous Mg(ClO4)2 under green conditions.

Base-promoted Lewis acid catalyzed synthesis of quinazoline derivatives

A one-pot protocol has been developed for the synthesis of quinazolinones from amide-oxazolines with TsCl via a cyclic 1,3-azaoxonium intermediate and 6π electron cyclization in the presence of a Lewis acid and base. The process is operationally simple and has a broad substrate scope. This method provides a unique strategy for the construction of quinazolinones.

ortho-Naphthoquinone-catalyzed aerobic oxidation of amines to fused pyrimidin-4(3H)-ones: a convergent synthetic route to bouchardatine and sildenafil

A facile access to fused pyrimidin-4(3H)-one derivatives has been established by using the metal-free ortho-naphthoquinone-catalyzed aerobic cross-coupling reactions of amines. The utilization of two readily available amines allowed a direct coupling strategy to quinazolinone natural product, bouchardatine, as well as sildenafil (Viagra™) in a highly convergent manner.

Fused pyrimidin-4(3H)-one derivatives have been accessed by using the ortho-naphthoquinone-catalyzed aerobic cross-coupling reactions of amines.

Aerobic oxidative synthesis of quinazolinones and benzothiazoles in the presence of laccase/DDQ as a bioinspired cooperative catalytic system under mild conditions

The current study applied laccase/DDQ as a bioinspired cooperative catalytic system for the synthesis of quinazolinones (80–95% yield) and benzothiazoles (65–98% yield) using air or O₂ as ideal oxidants in aqueous media at ambient temperature. The aerobic oxidative cyclization reactions occur in two steps: (i) chemical cyclization; (ii) chemoenzymatic oxidation. These methods are more environment-friendly, efficient, simple and practical than other reported methods due to the use of O₂ as an oxidant, laccase as an eco-friendly biocatalyst, aqueous media as the solvent and free from any toxic transition metal and halide catalysts. Therefore, these methods can be applied in pharmaceutical and other sensitive synthetic procedures.

In this paper laccase/DDQ as a bioinspired cooperative catalytic system was applied for the synthesis of quinazolinones and benzothiazoles using air or O₂ as ideal oxidant in aqueous media under mild conditions.

2,3-Dihydroquinazolin-4(1H)-one as a privileged scaffold in drug design

2,3-Dihydroquinazolin-4-one (DHQ) belongs to the class of nitrogen-containing heterocyclic compounds representing a core structural component in various biologically active compounds. In the past decades, several methodologies have been developed for the synthesis of the DHQ framework, especially the 2-substituted derivatives. Unfortunately, multistep syntheses, harsh reaction conditions, and the use of toxic reagents and solvents have limited their full potential as a versatile fragment. Recently, use of green chemistry and alternative strategies are being explored to prepare diverse DHQ derivatives. This fragment is used as a synthon for the preparation of biologically active quinazolinones and as a functional substrate for the synthesis of modified DHQ derivatives exhibiting different biological properties. In this review, we provide a comprehensive assessment of the synthesis and biological evaluations of DHQ derivatives.

Palladium-catalyzed oxidative CC bond cleavage with molecular oxygen: one-pot synthesis of quinazolinones from 2-amino benzamides and alkenes

Palladium-catalyzed oxidative cleavage/cyclization has been disclosed for the concise synthesis of various quinazolinone derivatives from readily available 2-aminobenzamides and terminal alkenes with excellent functional group tolerance.

Organic–inorganic hybrid polyoxometalate and its graphene oxide–Fe3O4nanocomposite, synthesis, characterization and their applications as nanocatalysts for the Knoevenagel condensation and the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

Organic–inorganic hybrid of H₆Cu₂[PDA]₆[SiW₉Cu₃O₃₇]·12H₂O (HybPOM), was synthesized and grafted on graphene oxide decorated with Fe₃O₄. The structures of HybPOM and GO@Fe₃O₄@HybPOM nanocomposites were characterized and their catalytic activities investigated.

Cleavage of the C–C triple bond of ketoalkynes: synthesis of 4(3H)-quinazolinones

A novel strategy to 4(3H)-quinazolinones from ketoalkynes and o-aminobenzamides through C–C triple bond fragmentation and two C–N bond formations under external oxidant and metal free conditions.

Recent advances in 4(3H)-quinazolinone syntheses

The new routes and strategies for the synthesis of valuable 4(3H)-quinazolinones have been summarized.

Copper-catalyzed tandem N-arylation/condensation: synthesis of quinazolin-4(3H)-ones from 2-halobenzonitriles and amides

A novel, straightforward and practical copper-catalyzed domino protocol for synthesis of quinazolin-4(3H)-one derivatives from commercially available 2-halobenzonitriles and amides was successfully developed.

Oxidant- and metal-free synthesis of 4(3H)-quinazolinones from 2-amino-N-methoxybenzamides and aldehydes via acid-promoted cyclocondensation and elimination

This paper presents a novel one-pot synthesis of biologically relevant 4(3H)-quinazolinones, in the absence of oxidants or heavy-metal catalysts.