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45 results on '"Saidi, Ourida"'

2. A New Homogeneity Inter-Clusters Measure in SemiSupervised Clustering

Author

Meftahi, Badreddine and Saidi, Ourida Ben Boubaker

Subjects
Computer Science - Learning, 62H30, 91C20, 68P15, 68T05, H.2.8, H.3.3, I.2, I.5.3
Abstract

Many studies in data mining have proposed a new learning called semi-Supervised. Such type of learning combines unlabeled and labeled data which are hard to obtain. However, in unsupervised methods, the only unlabeled data are used. The problem of significance and the effectiveness of semi-supervised clustering results is becoming of main importance. This paper pursues the thesis that muchgreater accuracy can be achieved in such clustering by improving the similarity computing. Hence, we introduce a new approach of semisupervised clustering using an innovative new homogeneity measure of generated clusters. Our experimental results demonstrate significantly improved accuracy as a result., Comment: 9 pages, 27 figures, International Journal of Computer Applications see http://www.ijcaonline.org/

Published
2013
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3. Hydroformylation of Functionalised Olefins

Author

Saidi, Ourida

Subjects
547.4
Abstract

Electronic and steric effects induced by various phosphine ligands on the regioselective rhodium-catalysed hydroformylation of butyl acrylate and enamides were investigated in this thesis. The first chapter describes the hydroformylation reactions reported in the literature, followed by chapter two, which presents the synthesis of modified dppb and phosphite ligands based on a biphenol and binol backbone. Ligand design represents a straightforward way to control the outcome of f the reaction, such as the catalytic regioselectivity and activity. The influence of modified dppb and phosphite ligands as well as some other parameters on the hydroformylation reaction was investigated; this forms the content of the third chapter contained within this thesis. As a result of the work featured here, we deduced that because electron deficient phosphine and phosphite ligands showed an increase in the rate of the reaction for butyl acrylate, leading to a higher activity of the rhodium catalyst, it appears that the CO dissociation is the rate-determining step; this is in line with the literature. The maximum rate and branched selectivity (95%) was obtained with dppbCF3 (TOF = 4743 hoI). This result was further extended to enamides in Chapter 4, where a similar observation on the reactivity was observed when using phosphite ligands bearing electron-withdrawing substituents. One of the most significant results is seen in the application of phosphite ligands for rhodiumcatalysed hydroformylation of enamines, which is to our knowledge, have not been previously employed for this type of the reaction. High-branched selectivity (up 99%) and high rate were observed in the hydroformylation ofvinylphthalimide in the presence of bulky phosphites, where the reaction was complete in less than 1 h.

Published
2007

6. Ferrocenyl phosphine-oxazaphospholidine oxide ligands for the Suzuki-Miyaura coupling of hindered aryl bromides and chlorides

Author

Vinci, Daniele, Martins, Nelson, Saidi, Ourida, Bacsa, John, Brigas, Amadeu, and Xiao, Jianliang

Subjects
Metallocenes -- Chemical properties -- Usage, Ferroalloys -- Chemical properties -- Usage, Chlorides -- Chemical properties -- Usage, Dichloropropane -- Chemical properties -- Usage, Chemical reactions -- Research -- Usage -- Chemical properties, Ligands -- Properties -- Usage -- Research -- Chemical properties, Aromatic amines -- Chemical properties -- Usage, Chemistry, Chemical properties, Usage, Research, Properties
Abstract

A series of ferrocenyl oxazaphospholidine phosphines that differ electronically and sterically were investigated as ligands for the Suzuki-Miyaura cross-coupling reactions. One of these compounds, 1, was shown to be highly effective in the coupling reactions of bulky aryl bromides with boronic acids when combined with Pd[(OAc).sub.2], while another, 2, was capable of coupling aryl chlorides with boronic acids. However, these ligands were less effective in asymmetric induction. Key words: Suzuki--Miyaura coupling, ferrocenyl phosphines, aryl bromides, aryl chlorides, palladium. Une serie de ferrocenyl oxazaphospholidine phosphines qui presentent des differences tant electroniques que steriques a ete etudiee comme ligands pour les reactions de couplage croise de Suzuki-Miyaura. On a montre qu'un de ces composes, 1, lorsqu'il est combine au Pd[(OAc).sub.2], est tres efficacle dans les reactions de couplage de bromures d'aryles avec des acides boroniques alors que le compose 2 permet d'effectuer le couplage de chlorures d'aryles avec les acides boroniques. Toutefois, ces ligands sont moins efficaces dans l'induction asymetrique. Mots-cles : couplage de Suzuki-Miyaura, ferrocenyl phosphines, bromures d'aryles, chlorures d'aryles, palladium. [Traduit par la Redaction], Introduction The palladium-catalyzed cross-coupling reactions of organoboron compounds and organic halides or triflates have emerged as a powerful and general methodology for the formation of carbon--carbon bonds (1-7). Advances in [...]

Published
2009

11. Regioselective Heck vinylation of electron-rich olefins with vinyl halides: is the neutral pathway in operation?

Author

McConville, Matthew, Saidi, Ourida, Blacker, John, and Jianliang Xiao

Subjects
Olefins -- Electric properties, Olefins -- Structure, Palladium catalysts -- Chemical properties, Biological sciences, Chemistry
Abstract

Highly regioselective vinylation of electron-rich olefins by bromo- as well as chlorostyrenes is influenced by palladium catalysis with either mono- or bidentate phosphines in a molecular solvent, where halide scavengers, ionic liquids or ionic additives are not required. In contrast to the related arylation reaction, the studies have shown that the vinylation has proceeded via the neutral Heck mechanism.

Published
2009

12. Direct acylation of aryl bromides with aldehydes by palladium catalysis

Author

Jiwu Ruan, Saidi, Ourida, Iggo, Jonathan A., and Jianliang Xiao

Subjects
Aldehydes -- Chemical properties, Aldehydes -- Structure, Palladium -- Chemical properties, Palladium -- Structure, Aromatic amines -- Chemical properties, Aromatic amines -- Structure, Acylation -- Analysis, Chemistry
Abstract

An efficient protocol is developed for the direct acylation of aryl bromides with various aldehydes, thus obtaining alkyl aryl ketones in good yields. The reaction has involved cocatalysis of palladium and amine.

Published
2008

29. Oxygen and base-free oxidative Heck reactions of arylboronic acids with olefins

Author

Jiwu Ruan, Xinming Li, Saidi, Ourida, and Jianliang Xiao

Subjects
Olefins -- Chemical properties, Palladium -- Usage, Aromatic compounds -- Chemical properties, Chemistry
Abstract

A new method is described that has allowed efficient oxidative Heck coupling of arylboronic acids with both electron-rich and -deficient olefins. This method does not require oxygen or base to operate, which has enhanced the scope of palladium-catalyzed coupling reactions.

Published
2008

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