Facile and efficient synthesis of 2-substituted-Nl-carbethoxy-2,3-dihydro-4(1H)-quinazolinones in fluorous solvent

A facile, efficient and novel approach to access 2-substituted-N1-carbethoxy-2,3-dihydro-4（1H）-quinazolinones was developed by condensation of substituted N-carbethoxyanthranilamide with alkyl, aromatic or heteroaromatic aldehydes in the refluxing 2,2,2- trifluoroethanol or hexafluoroisopropanol using p-toluenesulfonic acid as catalyst.

Copper-Catalyzed Aerobic Oxidative Ring Expansion of Isatins: A Facile Entry to Isoquinolino-Fused Quinazolinones

A copper-catalyzed aerobic oxidative ring expansion reaction of isatins with 1,2,3,4-tetrahydroisoquinoline for the synthesis of tetra-cyclic quinazolinones has been developed.This reaction is performed smoothly under simple conditions to give the corresponding products in moderate to good yields with good functional group tolerance.

Synthesis of quinazolinones from o-aminobenzamides and benzyl amines under metal-free conditions

A convenient and transition-metal free protocol for quinazolinones synthesis with o-aminobenzamides and benzyl amines as substrates has been developed. Using H;O;as the oxidant, various quinazolinones were obtained in moderate to good yields under metal- and additive-free conditions.

Visible light induced tandem reactions:An efficient one pot strategy for constructing quinazolinones using in-situ formed aldehydes under photocatalyst-free and room-temperature conditions

A facile tandem route has been developed for constructing quinazolinones from various aminobenzamides and in-situ generated aldehydes.Visible light was found to play a dual role:first oxidizes the alcohol to the aldehyde and then facilitates its cyclization with o-substituted aniline.Furthermore,alcohols are perfe ct alternatives to aldehydes because they are greene r,more available,more economical,more stable,and less toxic tha n aldehydes.The first reaction step continuously provides material for the second step,which effectively reduces loss through volatilization,oxidation,and polymerization of the aldehyde,while avoiding its toxicity.A variety of quinazolinones can be prepared in the presence of visible light without any additional photocatalyst.The developed synthesis protocol proceeds with the merits of mild conditions,broad substrate scope,operational simplicity,a nd high atom efficiency,with an eco-energy source under metal-free,photocatalyst-free,and ambient conditions.

Magnetically recyclable copper modified GO/Fe_3O_4 catalyst for efficient synthesis of quinazolinones

A series of bioactive quinazolinones were effectively synthesized by the condensation of halide benzamide with amino acid using magnetically recyclable GO/Fe3O4–CuI as catalyst. Magnetic GO/Fe3O4–CuI was prepared via a simple chemical method and characterized by FTIR, powder XRD, and SEM.This heterogeneous copper catalyst can be easily separated from reaction mixtures by an external permanent magnet and reused without any obvious loss in activity which shows its applicability as a reusable and promising catalyst for quinazolinones synthesis.

Synthesis,Crystal Structure and Fe^(3+)Recognition of a Fluorescent Probe Based on Quinazolinone Derivative

A novel quinazolinone derivative ethyl 2-(2-methyl-4-oxo-1,2,3,4-tetrahydroquinazolin-2-yl)ace-tate(EMOTA)was synthesized and characterized by HRMS,^(1)H NMR,^(13)C NMR spectroscopy and X-ray crystal-lography,and the ion recognition performance of the compound was studied by fluorescence analysis measure-ments.The results showed that probe EMOTA has a rapid fluorescence response,good selectivity and sensitivity to Fe^(3+).When the concentration of Fe^(3+)was in the range of 0~10.0×10^(-5)mol/L,the fluorescence quenching could be affected by the probe,and the detection limit was 1.65×10^(-6)mol/L.In addition,the identification and detection of Fe^(3+)in water samples were studied,and the results showed that probe EMOTA has high efficiency,significant sen-sitivity and high selectivity on the recognition and detection of Fe^(3+)in water samples,which indicates probe EMOTA has a practical application prospect.

Rapid and mild synthesis of quinazolinones and chromeno[d]pyrimidinones using nanocrystalline copper(Ⅰ)iodide under solvent-free conditions

This paper describes a very simple, efficient synthesis of quinazolinones and chromeno[d]pyrimidinones from the reaction of aryl aldehydes, urea/thiourea and active methylene compounds（dimedone/4-hydroxycoumarin） using nano-sized CuI particles under solvent-free conditions. The highlights of this new method are based on using an effective and recyclable catalyst, affording high yields of products,mild reaction conditions, facile work-up and purification.

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

A highly efficient synthesis of 2-aryl-quinazolin-4（3H）ones was performed by one-pot oxidative heterocyclization of 2- aminobenzamide with aldehydes in the presence of potassium permanganate in dimethylacetamide under microwave irradiation.

H-Y-zeolites induced heterocyclization:Highly efficient synthesis of substituted-quinazolin-4(3H) ones under microwave irradiation

A highly efficient synthesis of 2-amino-N-substituted-benzamides was performed by the condensation ofisatoic anhydride with several amines in solvent-free conditions under microwave irradiation. H-Y-zeolites induced heterocyclization of these products with ortho-esters under similar conditions afforded the relevant substituted-quinazolin-4（3H）ones in high yields.

Highly efficient solvent-free synthesis of quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones using tetrabutylammonium bromide as novel ionic liquid catalyst

A simple and efficient procedure for the synthesis of 2-arylquinazolin-4（3H）-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide（TBAB） as novel neutral ionic liquid catalyst in the presence of copper（Ⅱ） chloride（CuCl;） as oxidizing agent under solvent-free conditions at 100℃.In the absence of CuCl;and under a nitrogen atmosphere,the unoxidized intermediates,2-aryl-2,3-dihydroquinazolin-4（1H）-ones,were isolated. Treatment of these intermediates with CuCl;in TBAB media gave the oxidized products 2-arylquinazolin-4（3H）-ones.On the other hand,cyclocondensation of 2-aminobenzamide with aromatic aldehydes in TBAB under microwave irradiation directly gave 2- arylquinazolin-4（3H）-ones.

Clean heterocyclic synthesis in water:I_2/KI catalyzed one-pot synthesis of quinazolin-4(3H)-ones

Oxidative cyclocondensation of o-aminobenzamide with various aldehydes in water using I2/KI as catalyst and oxidizing agent is carded out giving the corresponding quinazolin-4（3H）-ones 3a-n in good to excellent yields.

Synthesis and evaluation of some novel additives as antioxidants and corrosion inhibitors for petroleum fractions

Benzoxazinone 2 was prepared and reacted with formamide,acetamide,some primary aromatic amines and heterocyclic amines giving the corresponding quinazolone derivatives 3-15 respectively.The reaction of benzoxazinone 2 with hydrazine hydrate and phenyl hydrazine was also studied.Representative compounds of the synthesized products were evaluated as antioxidants and corrosion inhibitors for gasoline engine lubricating oil.The highest antioxidant activities were obtained with compounds 10-15.The optimum concentration recommended for these new additives was found to be 0.lg for 1L ofoil for compounds 13-15.In addition,some of the highly effective antioxidant additives,namely 10-15,were thermally analyzed by using thermogravimetric analysis （TGA） and differential thermal gravimetric analysis （DTGA） techniques and the results indicated that compounds are thermally stable and could be used under thermal conditions.Moreover,a comparison of the oxidation stability between the tested oil containing the prepared products and lubricating oil containing commercial additives was also studied.

New conversion of Friendlnder reaction of 3-amino-1H-benzo[f]chromene-2-carbonitriles with cyclohexanone

Two different skeletons of heterocyclic compounds, quinoline and quinazolinone analogs could be obtained by a novel one-pot synthesis from substituted 3-amino- 1H-benzo[f]chromene-2-carbonitrile derivatives and cyclohexanone in DMF in the catalyst of anhydrous Zinc chloride under reflux. A plausible mechanism was proposed. 2007 Jia Rong Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Synthesis and Crystal Structure of 2-(4-Oxo-3-o- tolyl-3,4-dihydroquinazolin-2-ylthio)acetohydrazide

The title compound was synthesized from 3-（2-methylphenyl）-2-thioxo-2,3-dihy- droquinazolin-4（1H）-one （4） which was prepared from 2-methylaniline in two steps. The structure was supported by the spectroscopic data and unambiguously confirmed by single-crystal X-ray diffraction studies. It crystallizes in the orthorhombic space group Pbca with unit cell dimensions a = 6.687（4）, b = 24.788（16）, c = 30.453（19） V = 5048（5） 3 and Z = 8.

Three pairs of alkaloid enantiomers from the root of Isatis indigotica

Three pairs of enantiomerically pure alkaloids with diverse structure features, named isatindigoticoic acid A and epiisatindigoticoic acid A [(—)-1 and(+)-1], phaitanthrin A and epiphaitanthrin A [(—)-2 and(+)-2], and isatindopyrromizol A and epiisatindopyrromizol A [(—)-3and(+)-3], respectively, were isolated from an aqueous extract of the roots of Isatis indigotica. Racemic and scalemic mixtures of these enantiomers were separated by HPLC on a chiral semi-preparative column.Their structures including absolute configurations were determined by extensive spectroscopic analysis in conjunction with the calculation of electronic circular dichroism(ECD) spectra. The enantiomer pairs possess parent structures of 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid, indolo[2,1-b]quinazolinone, and 3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazol-1-one, respectively. Except for phaitanthrin A[(—)-2] which the configuration was previously undetermined, these compounds are new enantiomeric natural products.