Syntheses on the basis of 2H-chromen-2-one and 2H-chromene-2-thione

4-Hydroxy-2H-chromen-2-one and 4-hydroxy-2H-chromene-2-thione reacted with allyl bromide, 1,1,3-trichloroprop-1-ene, and 1,3-dichlorobut-2-ene to give the corresponding ethers, which were oxidized to (2-oxo-2H-chromen-4-yloxy)acetic acid with potassium permanganate, and various derivatives of that acid were obtained. 3-(3,3-Dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromen-2-one and 3-(3,3-dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromene-2-thione were synthesized, and some their transformations were studied.     

Synthesis,structure elucidation and plants growth promoting effects of novel quinolinyl chalcones

The readily synthesized 3-(4-Hydroxy-1-methyl-1,2-dihydro-2-oxoquinolin-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyd (5) and 3-(2-Oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde (6) were utilized as a convenient starting precursor materials for synthesis of novel enone system 4-hydroxy-1-methyl-3-(4-(2H-2-oxo-chromen-3-yl)prop-2-enoyl)-1-phenyl-1H-pyrazol-4-yl)quinolin-2(1H)-one (7) and4-hydroxy-1-methyl-3-(2E)-3-(3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazol-4-yl)acryloyl)quinolin-2(1H)-one (8). Simple homonuclear NOE experiment (NOESY 1D) method was performed for structure elucidation of the novel quinolinyl chalcones. The synthesized compounds have been estimated for their effect of growth on some selective crop of plants (Hibiscus, Mint and Basil).     

Chemoenzymatic synthesis of both enantiomers of 3-hydroxy-2,3-dihydro-4H-chromen-4-one

4-Oxo-3,4-dihydro-2-chromen-3-yl acetate is synthesized using manganese(III)acetate starting from 2,3-dihydro-4H-chromen-4-one. K₂CO₃ mediated hydrolysis of 4-oxo-3,4-dihdro-2-chromen-3-yl acetate furnished 3-hydroxy-2,3-dihydro-4H-chromen-4-one in high yield.The enantioselective hydrolysis of (±)-4-oxo-3,4-dihydro-2-chromen-3-yl acetate in various organic solvent-phosphate buffer (pH7) systems and enantioselective transesterification of (±)-3-hydroxy-2,3-dihydro-4H-chromen-4-one in organic solvents was investigated by screening a range of lipases. The lipase Amano PS, PPL, PLE and CCL-catalyzed asymmetric ester hydrolysis and transesterification afforded the enantiomers of 3-hydroxy-2,3-dihydro-4H-chromen-4-one and 4-oxo-3,4-dihydro-2-chromen-3-yl acetate with high enantiomeric excess (up to 97% ee) and in good yields.     

7-Chloro-4-methyl-6-nitro-2H-chromen-2-one: a novel type of reagent for fluorescence analysis

Starting from 7-chloro-4-methyl-2H-chromen-2-one 1 we have obtained a new reagent for fluorescence analysis. The synthesised key compound 7-chloro-4-methyl-6-nitro-2H-chromen-2-one 2 forms highly fluorescent derivatives with different amines, which can be introduced by nucleophilic substitution of the chloro atom. Two examples are given which describe the preparation of these derivatives. Additionally, we demonstrate that an increase of fluorescence can be achieved, if a reduction step is performed after the substitution.     

Reactions of 5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-ones with methylamine

5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-one reacts with methylamine to give methylammonium 5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, regardless of the solvent. The reaction of 3-acetyl-5,6,7,8-tetrafluoro-4-hydroxy-2H-chromen-2-one with the same amine in ethanol or acetonitrile leads to the formation of methylammonium 3-acetyl-5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, while in dimethyl sulfoxide 5,6,8-trifluoro-7-methylamino-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is formed. The latter is also formed in the reaction of 5,6,7,8-tetrafluoro-4-hydroxy-3-(1-iminoethyl)-2H-chromen-2-one with methylamine in DMSO, whereas in ethanol and acetonitrile 5,6,7,8-tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is obtained. 5,6,7,8-Tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione reacts with methylamine, yielding 7-mono-or 5,7-bis(methylamino)-substituted derivatives.     

Multicomponent condensation of 6-acetyl-5,7-dihydroxy-4-methylchromen-2-one with aldehydes and Meldrum´s acid

Previously unknown 6-acetyl-10-aryl-5-hydroxy-4-methyl-9,10-dihydropyrano[2,3-f]-chromene-2,8-diones were synthesized by multicomponent condensation of 6-acetyl-5,7-dihydroxy-4-methylchromen-2-one, aromatic aldehydes, and Meldrum´s acid. A fundamen-tal possibility of interconversion of substituted 6-acetyl-10-aryl-5-hydroxy-4-methyl-9,10-dihydropyrano[2,3-f]chromene-2,8-diones and methyl 3-(6-acetyl-5,7-dihydroxy-4-meth-yl-2-oxo-2H-chromen-8-yl)-3-arylpropionates was demonstrated.     

Synthesis and characterization of new thiazolidinones containing coumarin moieties and their antibacterial and antioxidant activities

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide) were synthesized starting from 4-methyl-7-hydroxycoumarin. The structures of the obtained compounds were confirmed by analytical IR and NMR spectra to elucidate the different positions of protons and carbons and as well as theoretical studies (DFT/B3LYP). The new compounds were screened for antibacterial activity. Most of them are more active against E. coli S. aureus and B. subtilis than standard references.     

Kinetic study and reactivity trends of hydroxide ion attack on some chromen-2-one laser dyes in binary water-methanol and water-acetone mixtures

The kinetics of base-catalyzed hydrolysis of 7-dimethylamino-4-methyl-2H-chromen-2-one (DMAC) and 7-diethylamino-4-methyl-2H-chromen-2-one (DEAC) in binary water-methanol and water-acetone mixtures were studied in the temperature range from 288 to 313 K. The activation and thermodynamic parameters of these reactions were evaluated and discussed. The change in the activation energy in going from water to aqueous methanol and aqueous acetone was estimated from the kinetic data. Base-catalyzed hydrolysis of DMAC) and DEAC in aqueous methanol and aqueous acetone follows the first-order kinetic law with respect to hydroxide ion, k _obs= k ₂[OH]. The hydrolysis rate constants of DMAC and DEAC decrease as the fraction of methanol or acetone in the binary mixture rises, which is due to destabilization of OH^? ion. The high negative entropies of activation support the proposed mechanism involving formation of an intermediate complex and reflect rigidity and stability of the latter. Opening of the pyran ring in the intermediate complex is the rate-determining step.     

Synthesis of 3-(3-Methyl-1-aryl-1H-pyrazol-5-yl)-2H-2-chromen-2-one Derivatives via a One-Pot,Three-Component Reaction

An efficient synthesis of 3-(3-methyl-1-aryl-1H-pyrazol-5-yl)-2H-2-chromen-2-one derivatives by the reaction of salicylaldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one, and arylhydrazine in acetonitrile under reflux condition and in the presence of piperidine is reported. This three-component reaction has some advantages such as ease of handling, good yields, and easy purification. All structures were confirmed by infrared, mass, ¹H NMR, and ¹³C NMR spectroscopy.     

Synthesis of new sulfanyl-, sulfinyl-, and sulfonyl-substituted polychlorobuta-1,3-dienes

New R-sulfanyl-substituted polychlorobuta-1,3-dienes were synthesized by reactions of hexachloro-1,3-butadiene or 1,1,2,4,4-pentachlorobuta-1,3-diene with dimethylbenzenethiols, heptane-1-thiol, and 4-methyl-7-sulfanyl-2H-chromen-2-one. Some sulfides were oxidized to the corresponding sulfoxides and sulfones or brominated with bromine. Among the synthesized compounds, the coumarin derivative, 4-methyl-7-(1,2,3,4,4-pentachlorobuta-1,3-dien-1-ylsulfanyl)-2H-chromen-2-one showed fluorescence properties. 1,1′,1″-[3,4-Dichlorobuta-1,3-diene-1,1,4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) reacted with potassium tert-butoxide in petroleum ether to afford a mixture of isomeric 1,1′,1″-[4-chlorobuta-1,2,3-triene-1,1.4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) and 1,1′,1″-[2-chlorobut-1-en-3-yne-1,1,4-triyltris(sulfanediyl)]-tris(2,4-dimethylbenzene). The GC/MS method was found to be useful for the separation of some sulfanyl-substituted butadiene isomer mixtures. The synthesized compounds were characterized by elemental analyses, mass spectrometry, UV-Vis, IR, and NMR (¹H, ¹³C) or fluorescence spectroscopy.     

Regioselective synthesis of novel substituted pyrazolo[1,5-a]pyrimidines under solvent-free conditions

A series of 6-(2-hydroxybenzoyl)-5-methyl-7-phenylpyrazolo[1,5-a]pyrimidines 5 have been synthesized directly by the solvent-free reaction between 5-amino-1H-pyrazoles 1 and 3-benzoyl-2-methyl-4H-chromen-4-one 4. This solvent-free reaction proceeds in a regiospecific fashion by intramolecular opening of the γ-pyrone ring in a Michael-type reaction, that followed by cyclization via nucleophilic attack of endocyclic pyrazole nitrogen toward benzoyl group gives the pyrazolo[1,5-a]pyrimidines 5. The use of this method affords high yields in short reaction times.     

Intramolecular amidation: synthesis of novel imidazo[2,1-b][1,3,4]thiadiazole and imidazo[2,1-b][1,3]thiazole fused diazepinones

Novel heterocyclic systems 2-alkyl/aryl-9-(2-hydroxybenzylidene)-7,9-dihydro-8H-[1,3,4]thiadiazolo[2′,3′:2,3]imidazo[4,5-d][1,2]diazepin-8-one and 9-(2-hydroxy-benzylidene)-3,3-dimethyl-3,4,7,9-tetrahydro-2H-11-thia-4b,6,7,10-tetraazaindeno[1,2-a]azulene-1,8-dione are synthesized via an intramolecular amidation reaction. An interesting ring opening and cyclization of 2-alkyl/aryl-6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehyde and 6,6-dimethyl-8-oxo-2-(2-oxo-2H-chromen-3-yl)-5,6,7,8-tetrahydroimidazo[2,1-b][1,3]benzothiazole-3-carbaldehyde are discussed.     

Synthesis of aromatic carbamates derivatives with a chromen-2-one fragment

Condensation of methyl N-(3-hydroxyphenyl)carbamate with ethyl trifluoromethylacetoacetate, 2-methoxyethyl acetoacetate in the presence of conc. sulfuric acid, and also with acetonedicarboxylic acid formed in situ from citric acid under the action of conc. sulfuric acid afforded chromene derivatives. The esterification of 2-{7-[(methoxycarbonyl)amino]-2-oxo-2H-chromen-4-yl}acetic acid with methanol in the presence of TsOH provided the corresponding ester. The oxidation of its α-methylene group with selenium dioxide led to the formation of methyl 2-{7-[(methoxycarbonyl)amino]-2-oxo-2H-chromen-4-yl}-2-oxo-acetate entering into a condensation with o-phenylenediamine resulting in a derivative with a dihydroquinoxaline fragment. The reaction of phenyl N-(4-formylphenyl)carbamate with 3-acetyl-2H-chromen-2-one in butanol in the presence of catalytic quantity of piperidine and acetic acid furnished 4-[(E)-3-oxo-2H-chromen-3-yl)-1-propenyl]phenyl N-phenylcarbamate.     

An efficient synthesis of 4-substituted coumarin derivatives via a palladium-catalyzed Suzuki cross-coupling reaction

An efficient Pd-catalyzed Suzuki cross-coupling reaction of sterically crowded 4-chlorocoumarin derivatives with air- and moisture-stable potassium organotrifluoroborates is developed. This methodology has been used to generate a series of novel alkyl, aryl, and vinyl substituted coumarin derivatives in good to excellent yields. The twisted conformation of the vinyl groups in the X-ray crystal structures of (2-oxo-4-vinyl-2H-chromen-3-yl)methyl acetate (2) and (2-oxo-4-vinyl-2H-chromen-3-yl)methyl 2,2,2-trichloroacetimidate (3), along with the atropisomerism of 3-(hydroxymethyl)-4-(2-methoxyphenyl)-2H-chromen-2-one (1d), are evidence of the steric crowding in these adducts.     

Highly regio- and diastereoselective three-component reaction of acyclic/cyclic donor–acceptor carbenoids for the synthesis of angularly fused furocoumarins and spirooxindolylfurocoumarins

A highly regio- and stereoselective method has been developed for the synthesis of spiro[furo[3,4-c]chromene-1,3′-indoline]-2′,4(9bH)-dione derivatives via a three component reaction of cyclic diazoamide and aldehyde with methyl 2-oxo-2H-chromene-3-carboxylate, 3-acetyl-2H-chromen-2-one and 3-benzoyl-2H-chromen-2-one using 3 mol % of Rh₂(OAc)₄. Similarly, acyclic diazoesters also undergo smooth coupling with carbonyl compounds and 3-substituted coumarin in the presence of 1 mol % of Rh₂(OAc)₄ to afford a novel series of tetrahydro-1H-furo[3,4-c]chromene-1-carboxylates in 78–88% yield with high regio- and stereo-selectivity for the first time.     

Synthesis,antioxidant, antibacterial,and DFT study on a coumarin based salen-type Schiff base and its copper complex

Synthesis of new efficient compounds is becoming urgent due to the resistance of organisms to drugs. Salen derivatives have interesting therapeutic and industrial applications. A coumarin based derivative of salen, 7-hydroxy-8-((E)-((2-((E)-((7-hydroxy-5-methyl-2-oxo-3,8a-dihydro-2Hchromen-8-yl)methylene)amino)-4-methylphenyl)imino)methyl)-5-methyl-2H-chromen-2-one (L), and its copper complex, CuL, have been synthesized and characterized. Antibacterial and antioxidant activity of these compounds have been evaluated and electronic, optical and molecular properties have been calculated using density functional theory (DFT) with B3LYP. The results were correlated with the biological activity and reactivity of the compounds. Experimental and theoretical calculations indicate that the studied copper complex has the potential to function as a drug.     

Iron(III) catalyzed direct C–H functionalization at the C-3 position of chromone for the synthesis of fused chromeno-quinoline scaffolds

This communication describes an iron-catalyzed route for the synthesis of 6-substituted chromeno[3,2-c]quinolin-7-one. The method developed does not require any pre-functionalization to execute the pivotal coupling reaction at the C-3 position of flavones. The final step involves the consecutive application of imine formation, C_sp²-C_sp² coupling and oxidation reaction, with aromatic aldehydes and 2-(2-aminophenyl)-4H-chromen-4-one as the reactants. Presence of electron donating/withdrawing groups was well tolerated in the aldehydes and the method developed could also be extended to other substituted 2-(2-aminophenyl)-4H-chromen-4-one’s. This is the first report of synthesis of 6-substituted chromeno[3,2-c]quinolin-7-one’s via direct functionalization of the C-3 site of flavones.     

Synthesis of nitrogen heterocycles underlain by application of 3-(4-Acetyl[phenyl)-2H-coumarin

3-(4-Acetylphenyl)-2H-chromen-2-one was obtained from 4-acetylphenyldiazonium chloride in the conditions of Meerwein reaction. Reactions of 3-[4-(2-bromoacetyl)phenyl]-2H-chromen-2-one with pyridine, 4-methylpyridine, quinoline, benzo[f]quinoline, and triphenylphosphine afforded quaternary salts, and with thioacetamide, thiourea, 2-aminopyridine, 2-aminopyrimidine, and 6-aminopurine provided the corresponding derivatives of thiazole, imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine, imidazo[2,1-i]purine. In the reaction of the same bromo derivative with thiosemicarbazide and aromatic aldehydes a thiazole ring is built and the corresponding hydrazones are formed.     

Synthesis of 3-methylquinazolin-4(3H)-one derivatives

Oxidation of 3-methyl-2-sulfanylquinazolin-4(3H)-one with chlorine dioxide under different conditions gave 2,2??-disulfanediylbis[3-methylquinazolin-4(3H)-one], 3-methyl-4-oxo-3,4-dihydroquinazoline-2-sulfonic acid, 3-methylquinazoline-2,4(1H,3H)-dione, 6-chloro-3-methylquinazoline-2,4(1H,3H)-dione, and N,N-diethyl-3-methyl-4-oxo-3,4-dihydroquinazoline-2-sulfonamide.     

Structure and stabilization factors of the 2-aminobenzimidazolium–3,3′-(phenylmethylene)- bis(4-hydroxy-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-one) anion associate in the system 4-hydroxy-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-one–benzimidazol-2-amine–benzaldehyde

The molecular and crystal structures of the ionic associate formed by 2-aminobenzimidazolium cation solvated by one dimethyl sulfoxide molecule and 3,3′-(phenylmethylene)bis(4-hydroxy-2H-chromen-2- one) anion were determined by X-ray analysis. This associate was isolated in the acid-catalyzed three-component reaction of 4-hydroxy-2H-chromen-2-one with benzimidazol-2-amine and benzaldehyde together with regioisomeric dihydrochromenopyrimidobenzimidazolones resulting from the classical Biginelli condensation. The steric and electronic structures of the cation and anion were calculated at the B3LYP/6-311++G(d,p) level of theory in combination with NBO analysis. Factors stabilizing the ion pair and crystal field effects on the stability of the associate and its constituents were considered. The formation of 3-[(2,4-dioxo-3H-chromen-3-yl)(phenyl)methyl]-2-oxo-2H-chromen-4-olate anion in the one-pot reaction was shown to be irreversible.