RESUME: Cet article présente une étude structurale détaillée réalisée sur trois échantillons de lignine (brute, purifiée et hydrolysée) extraite à partir de l'alfa tunisienne par le procédé CIMV. Les techniques spectroscopiques IRTF,...
moreRESUME: Cet article présente une étude structurale détaillée réalisée sur trois échantillons de lignine (brute, purifiée et hydrolysée) extraite à partir de l'alfa tunisienne par le procédé CIMV. Les techniques spectroscopiques IRTF, RMN 1 H et 13 C ont été utilisées dans la détermination des structures de ces lignines. La chromatographie à exclusion stérique ainsi que la spectrométrie MALDI-TOF/MS ont été employées dans la caractérisation de la distribution des masses molaires (M n , M w , I p) et l'identification des fragments de lignine. Les teneurs en groupements phénoliques et alcooliques ont été également déterminées. Les résultats obtenus montrent la présence d'oligomères principalement des associations du type (β-O-4), (β-5) et (γ-O-γ). La teneur en OH phénoliques est plus importante que celle en OH alcooliques. ABSTRACT: This paper presents a complete structural investigation of three lignin samples (crude, purified and hydrolyzed) isolated from Tunisian alfa li...
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The present study was directed to investigate the effect of precotreatment with (E)-N′-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide (7-hyd.HC), a novel potent synthesized coumarin, on isoproterenol- (ISO-) induced...
moreThe present study was directed to investigate the effect of precotreatment with (E)-N′-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide (7-hyd.HC), a novel potent synthesized coumarin, on isoproterenol- (ISO-) induced myocardial infarction (MI) in rats. The hydrazone compound was characterized by IR, 1D, and 2D NMR analyses. Experimental induction of MI in rats was established by ISO (85 mg/kg/day, s.c) for two consecutive days (6th and 7th days). 7-hyd.HC or sintrom was given for 7 days prior and simultaneous to ISO injection. 7-hyd.HC offered a cardiopreventive effect by preventing heart injury marker leakage (LDH, ALT, AST, CK-MB, and cTn-I) from cardiomyocytes and normalizing cardiac function and ECG pattern, as well as improving lipid profile (TC, TG, LDL-C, and HDL-C), which were altered by ISO administration. Moreover, 7-hyd.HC precotreatment significantly mitigated the oxidative stress biomarkers, as evidenced by the decrease of lipid peroxidation and the incr...
ABSTRACT A new approach to synthesis of a series of 3-carboxamidine iminocoumarins derivatives and substituted benzopyrano[2,3-d]pyrimidines was developed. The chemical structure of all the compounds was investigated by infrared, 1H NMR,...
moreABSTRACT A new approach to synthesis of a series of 3-carboxamidine iminocoumarins derivatives and substituted benzopyrano[2,3-d]pyrimidines was developed. The chemical structure of all the compounds was investigated by infrared, 1H NMR, 13C NMR, mass, and elemental analysis. The anticholinesterase activity of compound 12 was evaluated according to the modified Ellman’s method.
ABSTRACT 2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles were synthesized by Michael addition of various 3-cyanoiminocoumarins and β-naphthol in good yield. The heterocyclization of these materials in an acidic medium leads new...
moreABSTRACT 2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles were synthesized by Michael addition of various 3-cyanoiminocoumarins and β-naphthol in good yield. The heterocyclization of these materials in an acidic medium leads new heterocyclic compounds, which have not previously been described, in moderate to good yields and good selectivity. The synthesized compounds were characterized by infrared, 1H NMR, 13C NMR, two-dimensional NMR, and elemental analysis.
ABSTRACT Synthesis of benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins was successfully performed using heterocyclization of 3-cyano iminocoumarin or their N-ethoxycarbonylated derivatives with semicarbazide reagents. Elemental...
moreABSTRACT Synthesis of benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins was successfully performed using heterocyclization of 3-cyano iminocoumarin or their N-ethoxycarbonylated derivatives with semicarbazide reagents. Elemental analysis, infrared, and 1H NMR spectral data confirmed the molecular structure of the newly synthesized compounds.
ABSTRACT 3-Phenyl-5,7-dimethoxycoumarin and 3-(2-thienyl)-7-methoxycoumarin were strongly fluorescent in organic solution, with quantum yields reaching 0.84. In contrast, the iminocoumarin analogs of these dyes were poorly emissive. This...
moreABSTRACT 3-Phenyl-5,7-dimethoxycoumarin and 3-(2-thienyl)-7-methoxycoumarin were strongly fluorescent in organic solution, with quantum yields reaching 0.84. In contrast, the iminocoumarin analogs of these dyes were poorly emissive. This shows that the behaviour of coumarins cannot be systematically transposed to their iminocoumarin analogs. The spectroscopic properties of iminocoumarin dimers were also examined. These dimers present little spectroscopic interest in comparison with the parent compounds. Above all, this study indicates the untapped potential of fluorescent 3-aryl-7-methoxycoumarins, which have scarcely been studied. In particular, 3-(2-thienyl)-7-methoxycoumarin exhibited good emission efficiency in a wide range of solvents, and could be very useful as a fluorescent label including in protic media.
The pulping of Alfa grass at atmospheric pressure using a mixture of formic acid/acetic acid/water was investigated. Different pulping variables were studied, especially the percentage of formic acid, acetic acid and water, pulping time,...
moreThe pulping of Alfa grass at atmospheric pressure using a mixture of formic acid/acetic acid/water was investigated. Different pulping variables were studied, especially the percentage of formic acid, acetic acid and water, pulping time, the liquor to fibre ratio and impregnation time. The obtained unbleached pulps were analysed in accordance with the Kappa number and the degree of polymerisation. The
The fluorescence properties of four derivatives of 3-thienyl-2-(N-dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7-position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state....
moreThe fluorescence properties of four derivatives of 3-thienyl-2-(N-dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7-position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state. The 7-diethylamino derivative was strongly fluorescent in various solvents, with marked solvatochromism. Its fluorescence was quenched by aggregation. In contrast, the methoxy derivatives were only moderately or weakly fluorescent in solution, but two of them were strongly photoluminescent in the crystalline state, owing to favourable molecular packing. The 6-methoxy derivative even exhibited spectacular crystallization-enhanced emission, examples of which are particularly rare for this type of dyes. Dyes were tested for biological use. The 7-diethylamino derivative led to particularly strong fluorescence staining of the cytoplasm of HCT-116 colon cancer cells. No fading was observed over prolonged illumination by the microscope light beam, but a p...
ABSTRACT If alkylene bromides are used instead of acid chlorides, the oxygen-containing ring of the starting material (I) is opened.
ABSTRACT A new approach to synthesis of a series of 3-carboxamidine iminocoumarins derivatives and substituted benzopyrano[2,3-d]pyrimidines was developed. The chemical structure of all the compounds was investigated by infrared, 1H NMR,...
moreABSTRACT A new approach to synthesis of a series of 3-carboxamidine iminocoumarins derivatives and substituted benzopyrano[2,3-d]pyrimidines was developed. The chemical structure of all the compounds was investigated by infrared, 1H NMR, 13C NMR, mass, and elemental analysis. The anticholinesterase activity of compound 12 was evaluated according to the modified Ellman’s method.
ABSTRACT 2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles were synthesized by Michael addition of various 3-cyanoiminocoumarins and β-naphthol in good yield. The heterocyclization of these materials in an acidic medium leads new...
moreABSTRACT 2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles were synthesized by Michael addition of various 3-cyanoiminocoumarins and β-naphthol in good yield. The heterocyclization of these materials in an acidic medium leads new heterocyclic compounds, which have not previously been described, in moderate to good yields and good selectivity. The synthesized compounds were characterized by infrared, 1H NMR, 13C NMR, two-dimensional NMR, and elemental analysis.
ABSTRACT Synthesis of benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins was successfully performed using heterocyclization of 3-cyano iminocoumarin or their N-ethoxycarbonylated derivatives with semicarbazide reagents. Elemental...
moreABSTRACT Synthesis of benzopyrano[2,3-c]pyrazoles and 3-triazolonyliminocoumarins was successfully performed using heterocyclization of 3-cyano iminocoumarin or their N-ethoxycarbonylated derivatives with semicarbazide reagents. Elemental analysis, infrared, and 1H NMR spectral data confirmed the molecular structure of the newly synthesized compounds.
The synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and corresponding N-ureaiminocoumarins is described. The condensation of these materials with oxalyl chloride leads to the corresponding N-parabanic iminocoumarins, which...
moreThe synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and corresponding N-ureaiminocoumarins is described. The condensation of these materials with oxalyl chloride leads to the corresponding N-parabanic iminocoumarins, which have not previously been described, in moderate or good yields and high selectivity. The structures were characterized by Fourier transform infrared, H and C NMR, and elemental analysis.
... Web of Science ®] View all references ] Derivatives incorporating isoxazole heterocycle possess a broad spectrum of pharmacological effectiveness such as antimicrobial, [ 6 6. Buron , C. ; ElKaim , L. ; Usla , A ... [ 9 9. Andres , I....
more... Web of Science ®] View all references ] Derivatives incorporating isoxazole heterocycle possess a broad spectrum of pharmacological effectiveness such as antimicrobial, [ 6 6. Buron , C. ; ElKaim , L. ; Usla , A ... [ 9 9. Andres , I. ; Alcazar , J. ; Alonso , JM ; De Lucas , AI ; Iturrino , L ...
Reaction of 3-aryl iminocoumarins with diacid chlorides as C-electrophilic reagents under mild conditions novel bis-iminocoumarins in good yields. When the reaction was performed with alkylene dibromides by heating them in toluene in the...
moreReaction of 3-aryl iminocoumarins with diacid chlorides as C-electrophilic reagents under mild conditions novel bis-iminocoumarins in good yields. When the reaction was performed with alkylene dibromides by heating them in toluene in the presence of IRA 900 resin, bis-ether compounds were obtained by way opening the pyranic ring. The structures of the product obtained were characterized by Fourier transform infrared, H NMR, C NMR, and elemental analysis.
ABSTRACT We report here a novel, one-pot, two-step reductive amination of aldehydes for the atom-economical synthesis of primary amines. The amination step has been carried out with hydroxylammonium chloride and does not require the use...
moreABSTRACT We report here a novel, one-pot, two-step reductive amination of aldehydes for the atom-economical synthesis of primary amines. The amination step has been carried out with hydroxylammonium chloride and does not require the use of a base. In the subsequent reduction step, a metal zinc/hydrochloride acid system has been used. This method is applicable to both aliphatic and aromatic aldehydes. The operational simplicity, the short reaction times, and the mild reaction conditions add to the value of this method as a practical alternative to the reductive amination of aldehydes.Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.
ABSTRACT Enantiopure vinyl ethers of Stericol® underwent diastereoselective thermal 1,3 dipolar cycloadditions with N-benzyl, N-benzhydryl, and N-PMB aspartate ester nitrones. Chemoselective N-debenzylation of the resulting cycloadducts...
moreABSTRACT Enantiopure vinyl ethers of Stericol® underwent diastereoselective thermal 1,3 dipolar cycloadditions with N-benzyl, N-benzhydryl, and N-PMB aspartate ester nitrones. Chemoselective N-debenzylation of the resulting cycloadducts afforded diastereomerically and enantiomerically pure crystalline NH-isoxazolidine, the absolute configuration of which was established by X-ray crystallography. N-Protection and N–O cleavage of this isoxazolidine gave enantioenriched quaternary aspartate derivatives bearing functionalized side chains.
ABSTRACT 3-Phenyl-5,7-dimethoxycoumarin and 3-(2-thienyl)-7-methoxycoumarin were strongly fluorescent in organic solution, with quantum yields reaching 0.84. In contrast, the iminocoumarin analogs of these dyes were poorly emissive. This...
moreABSTRACT 3-Phenyl-5,7-dimethoxycoumarin and 3-(2-thienyl)-7-methoxycoumarin were strongly fluorescent in organic solution, with quantum yields reaching 0.84. In contrast, the iminocoumarin analogs of these dyes were poorly emissive. This shows that the behaviour of coumarins cannot be systematically transposed to their iminocoumarin analogs. The spectroscopic properties of iminocoumarin dimers were also examined. These dimers present little spectroscopic interest in comparison with the parent compounds. Above all, this study indicates the untapped potential of fluorescent 3-aryl-7-methoxycoumarins, which have scarcely been studied. In particular, 3-(2-thienyl)-7-methoxycoumarin exhibited good emission efficiency in a wide range of solvents, and could be very useful as a fluorescent label including in protic media.
ABSTRACT A liquid/liquid interfacial technique was used to prepare biscoumarin dyes by condensing 7-hydroxy-4-methylcoumarin with various diacyl chlorides in the presence of a phase-transfer catalyst such as triethylbenzylammonium...
moreABSTRACT A liquid/liquid interfacial technique was used to prepare biscoumarin dyes by condensing 7-hydroxy-4-methylcoumarin with various diacyl chlorides in the presence of a phase-transfer catalyst such as triethylbenzylammonium chloride. The reaction conditions were optimized. Six new biscoumarin derivatives were thus prepared in high yield. Their optical properties were studied in chloroform by UV/vis absorption and fluorescence spectroscopies. It appeared that the shape of the absorption spectra varies with the nature of the tether between both chromophores. In contrast, the excitation and emission spectra were almost unchanged, although the compounds exhibited drastic differences in their fluorescence efficiency.
ABSTRACT Alfa grass pulping was successfully performed in hydro-organic acid medium under mild conditions (107°C, atmospheric pressure, cooking time: 3 h). Use of an acetic acid/formic acid/water mixture as pulping liquor was perfectly...
moreABSTRACT Alfa grass pulping was successfully performed in hydro-organic acid medium under mild conditions (107°C, atmospheric pressure, cooking time: 3 h). Use of an acetic acid/formic acid/water mixture as pulping liquor was perfectly suitable for selective isolation of pulp, lignin, and hemicelluloses. The unbleached pulp obtained in good yield was first delignified by peroxyacids in organic acid medium and then bleached with hydrogen peroxide in a basic medium to give pulp offering good physico-chemical and mechanical characteristics.
The double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O-N acyl transfer, providing a very simple and general access to...
moreThe double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O-N acyl transfer, providing a very simple and general access to α,α,α-trisubstituted amides.
Alfa grass lignin obtained by the acetic acid/formic acid/water CIMV pulping process was characterized by FTIR and (1)H, (13)C-(1)H 2D HSQC, and (31)P NMR spectroscopies. Lignin samples purified by further dissolution/precipitation or...
moreAlfa grass lignin obtained by the acetic acid/formic acid/water CIMV pulping process was characterized by FTIR and (1)H, (13)C-(1)H 2D HSQC, and (31)P NMR spectroscopies. Lignin samples purified by further dissolution/precipitation or basic hydrolysis steps were also analyzed. The CIMV alfa lignin is a mixture of low molar mass compounds (M(n) = 1500 g/mol) of SGH type with β-O-4 ether bonds as the major interunit linkage. The crude lignin contains fatty acids and residual polysaccharides. It also contains large amounts of acetate and hydroxycinnamates, mostly in the γ-position of β-O-4 interunit linkages. Although partial acetylation induced by the process cannot be excluded, the absence of aromatic acetates and acetylated polysaccharides in crude lignin demonstrates the mildness of the process. By combining smooth alkaline hydrolysis and dissolution/precipitation steps to the CIMV pulping, it is possible to produce a purified lignin with a composition and a structure quite analogous to that of the native polymer in the plant.
