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The generation of a methyl carbon source from renewable and cheap sources is challenging. Herein, we describe a novel and an efficient route for methylation and acetylation of aza-heteroarenes using PEG-400 under O2and TsOH·H2O for the first time by tuning the reaction conditions using a different set of starting materials. The key features of the current protocol are oxidative C-O and C-C bond scission under metal-free conditions with good functional group tolerance, and a broad substrate scope. The potential applicability of the designed methodology was demonstrated for the synthesis of central nervous system (CNS) depressant and anticonvulsant drug molecules by a one-pot strategy.

The invention relates to the technical field of chemical synthesis and especially relates to a one-pot synthesis method of a quinazolinone compound, which includes the steps of: (1) with an alcohol, represented as the formula (I), as a raw material, performing a reaction under effect of a photosensitizer in the conditions of light irradiation, gas and room temperature in a solvent to generate an aldehyde represented as the formula (II); (2), with the aldehyde (II) and an o-aminobenzamide derivative represented as the formula (III) as raw materials, performing a reaction under effect of the photosensitizer and an acidic compound in the conditions of light irradiation, gas and room temperature in a solvent to generate a quinazolinone compound represented as the formula (IV). The method is used for synthesizing the quinazolinone compound through a one-pot process. The method is simple in process and employs simple and accessible raw materials, is free of metal catalyst, is carried out through room-temperature reactions with green photocatalysts, is free of peroxides, is low in raw material cost, is high in yield, and is energy-saving and environment-friendly.

A mild and greener protocol was developed to synthesize substituted quinazolinones and dihydroquinazolinones via deep eutectic solvent (DES) mediated cyclization with a series of aliphatic, aromatic, and heteroaromatic aldehydes in good to excellent yields. This greener strategy was further utilised to synthesize various quinazolinone natural products and drugs.

We developed a copper-catalyzed tandem reaction of 2-aminobenzamides with tertiary amines for the formation of quinazolinone derivatives. The strategy includes two steps (cyclization and coupling) performed in one pot. A number of substrates reacted well under standard conditions to give the corresponding quinazolinone derivatives in moderate to good yields.

Simple, convenient, and green synthetic protocols have been developed for the one pot synthesis of 2,3-disubstituted quinazolin-4(3H)-ones and 2-styryl-3-substituted quinazolin-4(3H)-ones under catalyst and solvent free conditions. The multicomponent reaction (3-MCR) involving isatoic anhydride, an amine, and orthoester afforded the 2,3-disubstituted quinazolin-4(3H)-ones in excellent yields under classical heating at 120 °C for 5 h or under microwave irradiation at 140°C for 20-30 min. The use of ammonium acetate instead of the amine provides the 2-substituted quinazolin-4(3H)-ones. The reactions are compatible with various substituted isatoic anhydrides, aryl/heteroaryl/alkyl/cycloalkyl amines, and orthoesters. The strategies are extended to the one pot tandem condensation involving isatoic anhydride, an amine, orthoester, and aldehyde to afford highly functionalized (E)-3-aryl/heteroaryl-2-styrylquinazolin/(2-(heteroaryl)vinyl)quinazolin-4(3H)-ones. The applications of the methodologies are demonstrated through the synthesis of various drugs which act on the central nervous system such as methaqualone, mebroqualone, mecloqualone, piriquialone, and diproqualone.

A simple and elegant method for benzylic activation was demonstrated employing the potassium iodide/tert-butyl hydrogen peroxide catalytic system. This methodology was further extended for the synthesis of biologically important heterocycles namely, 3H-quinazolin-4-ones and 4H-3,1-benzoxazin-4-ones including mecloqualone and etaqualone which are important quinazolinone-based drugs used for the treatment of insomnia in good yields.

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Synthesis of 2-(ω -chloroacetonyl)-3-substituted-phenyl-6-halo/6,8-dihaloquinazolin-4(3H)-ones 6-10, 2-(ω -hydrazinoacetonyl)-3-substituted-phenyl-6-halo/6,8-dihaloquinazolin-4(3H)ones 11-15 and 1′ -[3H-3-substituted-phenyl-4-oxo-6-halo/6,8-dihaloquinazolin-2-acetonyl] -3′-aryl-5′-(2-substituted-indol-3-yl)-Δ 2-pyrazolines 16-30 have been described. All the compounds have been tested in vivo for their anti-inflammatory, analgesic, ulcerogenic activities and acute toxicity.

Piriqualone (1) was found to be an antagonist of AMPA receptors. Structure-activity optimization was conducted on each of the three rings in 1 to afford a series of potent and selective antagonists. The sterically crowded environment surrounding the N-3 aryl group provided sufficient thermal stability for atropisomers to be isolated. Separation of these atropisomers resulted in the identification of (+)-38 (CP-465,022), a compound that binds to the AMPA receptor with high affinity (IC50 = 36 nM) and displays potent anticonvulsant activity.

Quinazolin-4-one derivatives of methaqualone substituted at C-2 define new class of noncompetitive antagonists at AMPA receptors. (C) 2000 Elsevier Science Ltd. All rights reserved.

A number of arylfurylvinylquinazolinones were prepared as possible antibacterial agents. The structural elucidations of all the compounds were carried out on the basis of analytical and spectral data. The newly synthesized compounds were screened for their antibacterial properties against both Gram-positive and Gram-negative bacteria.

A series of 4(3H)-quinazolinones structurally related to 2-methyl-3-o-tolyl-4(3H)-quinazolinone (methaqualone, 3) were synthesized and evaluated for anticonvulsant activity.Preliminary screening of these compounds revealed that 2--3-aryl-4(3H)-quinazolinones 6l and 8i, 8k, and 8p-r having a single ortho substituent on the 3-aryl group had the most promising anticonvulsant activity.Compounds 6l and 8i possessing 3-o-tolyl and 3-o-chlorophenyl groups, respectively, showed good protection against MES- and scMet-induced seizures, combined with relatively low neurotoxicity after intraperitoneal administration in mice.They also exhibited low toxicity in tests for determining the mean hypnotic dose (HD50) and the median lethal dose (LD50).Although these compounds were markedly more potent as anticonvulsants when administered orally in mice and rats, they were also more neurotoxic.This neurotoxicity was particularly acute in oral tests with rats. which resulted in marginal protective indices.In drug differentiation tests, compound 6l was ineffective against seizures induced by bicuculline, picrotoxin, and strychnine, while 8i showed some protection against picrotoxin-induced seizures.

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