JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthèse de pyrazoles F-alkylés

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The condensation of F-alkyl hydrazinoalcohols 1 and N-Acyl, F-alkyl hydrazides 6 with β-diketones 2 allowed a convenient synthesis of new pyrazoles 3, 4, 7 et 8.

I. Mastouri, A. Baklouti

hydrazinoalcohols, hydrazide, F-alkylated pyrazoles

Pages 93-99

In vitro antioxidant activities of Aloe vera leaf skin extracts

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The ethanolic extract of Aloe vera leaf skin was fractionated by liquid-liquid partition using hexane, ethyl acetate, chloroform-ethanol and butanol. The total phenolic content of the four different fractions were determined by Folin-Ciocalteu method and their antioxidant activity was essayed through some in vitro models such as the antioxidant capacity by phosphomolybdenum method, β-carotene bleaching method, radical scavenging activity using 2,2-diphenyl-1-picryl hydrazyl (DPPH) assay and reducing power assay. The chloroform-ethanol fraction showed the highest total phenolics (40.500 ± 0.041 µg gallic acid equivalents/g of extract), the highest scavenging activity and the greatest reducing power, followed by ethyl acetate, butanol and hexane extracts. However, the hexane fraction showed the highest antioxidant capacity (471.300 ± 0.013) and the highest antioxidant activity coefficient (AAC) by the β-carotene bleaching method.

S. Miladi, M. Damak

Antioxidant activity, Aloe vera leaf skin, total phenols, DPPH, Reducing power, β-carotene

Pages 101-109

Contribution à l’étude de la réactivité d’iminoéthers N-fonctionnalisés : Synthèse de pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c] pyrimidines

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New pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines 3a-i have been synthesized through the cyclocondensation of 5-amino-4-iminopyrazolopyrimidines 2a-c and a series of electrophilic species incorporating one carbon unit.

A. Romdhane, B. Trimeche, S. Hammami, R. Gharbi, M.A. Hamza, Z. Mighri

5-amino-4-iminopyrazolopyrimidines, electrophilic species, pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines

Pages 111-117

Composition chimique et activités antioxydante, antimicrobienne et insecticide de l’huile essentielle de Juniperus phoenicea

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The essential oil composition of the leaf of Juniperus phoenicea from region of Medenine (The south of Tunisia) was investigated by GC, GC-MS. 27 constituents were identified correspond to 84.63% of the total oil. The major components are α-Pinene (59.11%), Linalool (3.3%), Germacrene D (1.55%) and Germacrene B (3.22%). Antioxidant action of this essential oil is proved in vegetal oil (soybean) and was effective in stabilizing lard against oxidation. Its activity is compared to that of δ-tocopherol. This oil has been tested for antimicrobial activity against two bacteria (Klebsiella oxytoca, Lactobacillus plantarum), yeast (Saccharomyces cereviseae) and fungi (Geotrichum candidum). Insecticidal properties of Juniperus phoenicea essential oil were investigated against Tribolium confusum insect pest of stored grains. This oil exhibited an interesting antifeedant activity. A preliminary study showed that this oil presented high toxicity against this insect.

N. Bouzouita, F. Kachouri, M. Ben Halima, M.M. Chaabouni

Juniperus phoenicea, Essential oil, Antioxidant activity, Antimicrobial activity, Insecticidal activity

Pages 119-125

Efficient synthesis of chiral 1,3-diols and of 1-substituted-propan-1-ols through asymmetric hydrogenation

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Asymmetric hydrogenations of an achiral β-keto ester using a chiral diphosphine-ruthenium catalyst to set the hydroxyl function in a stereo controlled manner were used in key-step towards the total synthesis of both enantiomers of secondary alcohols with excellent enantioselectivity (>99% ee) and high yields.

R. Touati, B. Ben Hassine

Asymmetric hydrogenation, atmospheric pressure, β-hydroxy esters, 1,3-diols, monotosylate 1,3-diols, secondary alcohols

Pages 127-139

Contribution to the phytochemical investigation of the plant Eryngium dichotomum Desf. (apiaceae) from Tunisia

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The butanolic extract of Eryngium dichotomum Desf. aerial parts afforded a Cyclohexenone glycoside 1, flavone glycoside : Naringenine 7-O-α-L-Rhamnopyranosyl-(1→2)-O-β-D-glucopyranoside 2, Sugar: β-Dfructofuranose 3, 2-O-methyl-α-D-fructofuranose 4, Sucrose 5 and D-mannitol 6. Their structures were principally elucidated by spectroscopic procedures and chemical data. These natural substances are signalled for the first time in Eryngium dichotomum Desf.

S. Nacef, H. Ben Jannet, M.A. Hamza, Z. Mighri

Cyclohexenone glycoside, Flavone glycoside, Sugar, Eryngium dichotomum, NMR

Pages 141-148

Highly stereoselective synthesis of some β-branched α-(phenylsulfonylmethyl) acrylic compounds

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Substitution reaction of E-branched Baylis-Hillman bromides with sodium benzenesulfinate in absolute ethanol at room temperature, produces in SN2 process and high stereoselectivity, the corresponding allyl phenyl sulfinates in good yields.

S. Khamri, T. Turki, H. Amri

Baylis-Hillman derivatives, nucleophilic substitution, allyl phenyl sulfones

Pages 149-155

Structure-dependent and morphology-dependent exchange of guests in permeable molecular crystals

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Our understanding of the properties of porous crystalline materials is largely based on studies of zeolites and other inorganic substances. The advent of new analogues, including purely molecular networks, has created opportunities to base knowledge of porous materials on a broader foundation. We have used permeable molecular crystals of tetrakis(3,5-dihydroxyphenyl)silane (1) to show how the exchange of guests depends on both structure and morphology. Specifically, exchange is faster in polymorphs with wider channels and in crystalline morphologies with well-developed faces that cut the channels.

O. Saied, T. Maris, S.F. Zalzal, J.D. Wuest

Crystal engineering, porous molecular networks, guests exchange, polymorphism, hydrogen bond

Pages 157-162

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