As direct precursors of α-amino acids, α-amino nitrile derivatives have prompted several research groups to develop new routes or improve existing ones to optimize the conditions involved in their synthesis. Efforts have primarily focused on a stereoselectivity and low catalyst loading. Here we report our preliminary results describing the use of simple, low-cost chiral carboxylic acids and α-amino acids as potential catalysts in the hydrocyanation reaction.
S. Barkallah, M. C. Kozlowski
α-amino acids, stereoselectivity, chiral, carboxylic acids, hydrocyanation
Depending on the nature of the base, 2-acétoxyméthylcyclopenténone 2a reacts regioselectively with β-dicarbonyl compounds to provide δ-diketones 3 and 4.
R. Gatri, M.M. El Gaïed
Baylis-Hillman acetate, 1-(hydroxymethyl)cyclopent-2-enone, δ-diketones
The N-acyl-2,2-dimethylaziridines 1 are rearranged in presence of aqueous solutions of H2SO4 (3 et 23% wt) at room temperature for four days into a mixture of oxazolines 2, amidoalcohols 3 and N-methallylamides 4 with yields depending on the acidity of the media and the nature of acyl group of the aziridine 1. An mechanism has been advanced to explain the formation of these three products 2, 3 and 4.
M. Kamoun Mhiri, F. Aboumessaad, M.L. Efrit, N. Besbes
acid rearrangement, N-acylaziridine, isomerisation, mechanistic study
The β-phosphonylated hydrazones have reacted with isothiocyanates and ethyl orthoformate to lead new compounds of thiosemicarbazones and 4-phosphonylpyrazoles and according to the reaction of Fischer to prepare a some derivatives of 2-phosphonylindoles.The structure of all compounds was confirmed by spectroscopy IR and NMR (1H, 31P, 13C, 19F).
N. Salah, S. Zribi, M.L. Efrit, A. Ben Akacha
β-phosphonylated hydrazone, thiosemicarbazone, 4-phosphonylpyrazole, 2-phosphonylindole, isothiocyanate, ethyl orthoformate
Novel phosphonothienopyrimidinone derivatives were synthesized in four steps by using phenylisothiocyanate and active methylene compounds. The structures of the obtained compounds were confirmed by IR and NMR (1H, 13C, 31P).
I. Jalloul, M.L. Efrit, A. Ben Akacha
Phosphonoacetonitrile-α-thioamides, Thiophenes, Phenylisothiocyanate, Ethylbromoacetate, Thienopyrimidinones
We describe in this work the study of the coupling of aryl halides with terminal alkynes in the presence of palladium-complex and Aliquat-336. This is an excellent catalyst system for the Sonogashira coupling under ultrasonic irradiation in optimized conditions at room temperature and in the absence of copper. Yields increased with the sonochemical activation in the presence of phase transfer catalysis for a very short duration. The isolated products are of high purity. In this regard, we propose reaction mechanisms that could explain the results.
L. Mhamdi, K. Said, Y. Moussaoui, R. Ben Salem
Sonogashira coupling, Ultrasound irradiation, Bi-activation, anionic activation, phase transfer catalysis
Periploca angustifolia is a native shrub of Mediterranean regions. Multiple uses (ecological, pastoral and medicinal) of this species incited us to make a chemical phytoscreening of many secondary metabolites and biochemical analysis as well the anti-radical activity of three organs (twigs, root barks and seeds). The qualitative study revealed the presence of several secondary metabolites. Quantitative analysis shows that twigs and root barks are, respectively, a source of protein (5.204 mg.g-1DM) and fatty matter (5.2 mg.g-1DM). Secondary metabolites assays have shown that twigs of P. angustifolia have levels significantly (P <0.05) higher on total polyphenols and carotenoids, than the other two studied parts (root barks and seeds). On the other hand, seeds are very rich in tannins and anthocyanins. The flavonoid content is not significantly different (P> 0.05) between the different studied parts (twigs, root barks and seeds). To determine the effect of secondary metabolites (tannins, total polyphenols, flavonoids and anthocyanins) on anti-radical activity, a correlation was performed. This correlation is a logarithmic type of which the correlation coefficient (R2) varies depending on the compound. The correlation is very high (R2 = 0.939) for tannins. So what is, this compound, which is responsible for the anti-radical activity of Periploca angustifolia.
F. Dghim, S. Zouari, M. Boukhris, M. Neffati
Apocynaceae, Periploca angustifolia, chemical composition, antiradical activity, tannins
The effect of pH, agitation speed and coagulant dosage on the coagulation performance of aluminium sulfate with respect to the treatment of Medjerda water was investigated in this paper. The measurement of residual aluminium speciation was also conducted. The evaluation of treatment efﬁciency of the optimization of coagulation process while was determined by measuring the reduction of turbidity, chemical oxygen demand (COD) and organic matter (OM). The optimal operational conditions are as follows: initial pH value of 6, concentration of aluminium sulfate of 30 mg.L-1 and agitation speed of 80 rpm.
M. Jaouadi, N. Amdouni
Raw water, coagulation, Aluminium sulfate, chemical oxygen demand, organic matter
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