L. Lopez
Paul Sabatier University
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Featured researches published by L. Lopez.
Tetrahedron Letters | 1984
O. Diallo; M.T. Boisdon; C. Malavaud; L. Lopez; M. Haddad; J. Barrans
Abstract Triazaphospholes react with 1,2-diketones to give spirocyclic phosphorus compounds by a 1.1 addition at phosphorus atom; with o-quinones one obtains spirobicyclic hexacoordinated phosphorus compounds. The reaction of 1,2-diketones with λ 3 -phosphazene oligomers appears different, to some extent, and can be used as a test for the existence of a monomer-oligomer equilibrium.
Tetrahedron | 1998
Anne Pujo-Bouteillé; Lydia Lamandé; L. Lopez; Louis Cazaux; Jacques Bellan
Abstract The reactions of diacids with the bicyclophosphane 1 lead to podands 3a-f in which two dioxazaphosphocane moieties are linked by a more or less rigid spacer owing to the starting diacid. Macrocycles 4a-b are obtained by cyclization of podands 3a-b by way of Michaelis-Becker reaction. The formation of Ca 2+ and Mg 2+ complexes with 3a-f and 4a-b has been investigated by UV, IR and NMR spectroscopies. Liquid-liquid extraction studies show for macrocycles efficient extracting properties and good selectivities of Ca 2+ towards Mg 2+ . The calcium transport across a chloroformic membrane agrees better with stability constants than with extraction data.
Tetrahedron Letters | 1986
O. Diallo; M. T. Boisdon; L. Lopez; C. Malavaud; J. Barrans
Addition of diazadienes 5 to dicoordinated phosphorus derivatives such as triazaphospholes 1 or diazaphospholes 3 leads to new tetracoordinated phosphorus spirocompounds 2 or 4. The tricoordinated phosphorus species 7 and 9 exist in a monomer tetramer PIII equilibrium but only the monomeric PII form reacts with diazadienes 5 leading to the spirocompounds 8 and 10. The monomers of 7 and 9 stabilized by complexation react with 5 to afford spirocompounds analogous to 2 and 4. In all these reactions the dicoordinated phosphorus atom is a good electrophile.
Tetrahedron Letters | 1999
B. El Azzaoui; J. Fifani; E.M. Tjiou; El Mokhtar Essassi; J. Jaud; L. Lopez; Jacques Bellan
Abstract New aza heterocycles with benzimidazole, pyrazole and pyridine moieties in the same molecule have been prepared. Preliminary complexing properties with divalent copper salts were determined by means of mass spectrometry (FAB) and a very interesting oxydation reaction with molecular oxygen was shown.
Tetrahedron Letters | 1991
Ousmane Diallo; L. Lopez; J. Barrans
Abstract The first step of hydrolysis of compounds 1 , 2 and 4 involves the protonation of the PN nitrogen atom. 3 does not react with water in the absence of a catalyst. Protonation of compounds 1 – 3 by a strong acid such as CF3SO3H is studied by 15N and 31P nmr spectroscopy. In all cases the PN nitrogen appears to be the strongest basic site.
Tetrahedron Letters | 1987
Th.N'Gando M'Pondo; C. Malavaud; L. Lopez; J. Barrans
Resume The title compounds were obtained by reaction of diamidrazones with tris(dimethylamino)phosphine. The bitriazaphosphole structure is consistent with mass spectra. The reactivity of these new compounds and of triazaphosphole derivatives seems to be the same.
Journal of The Chemical Society, Chemical Communications | 1984
L. Lopez; Jean-Pierre Majoral; Abdelkader Meriem; Théophile N'Gando M'Pondo; Jacques Navech; J. Barrans
The reaction of the Schiff bases of benzamidrazone or diaminomaleonitrile with bis(dimethylamino)chlorophosphine or tris(dimethylamino)phosphine affords new 1H, 2H-, or 4H-1,2,4,3λ3-triazaphospholes or 1,3,2λ3-diazaphospholes with the formation of triaza- or diaza-phosphorines as intermediates.
Phosphorus Sulfur and Silicon and The Related Elements | 2000
Y. Kandri Rodi; A. El Hallaoui; El Mokhtar Essassi; C. Dargelas; L. Lopez; Jacques Bellan
Abstract Nous décrivons la synthèse en quatre étapes de nouveaux 1,3-dihydrobenzodiazaphospholes 3 et 6a-c dont la particularité est de posséder un (3) ou deux (6a-c) motifs N-acyl-diazaphospholines. Seuls les ligands 6a-c présentent des propriétés complexantes vis-à-vis des ions alcalino-terreux. observables par spectrométrie IR et UV. We describe a four step synthesis of new 1,3-dihydrobenzodiazaphospholes 3 and 6a-c which posses one (3) or two (6a-c) N-acyl diazaphospholine moieties. Only the formation of alkaline-earth cation complexes, with 6a-c has been observed by IR and UV spectroscopies.
Phosphorus Sulfur and Silicon and The Related Elements | 1990
Ousmane Diallo; L. Lopez; J. Barrans
Abstract So far organophosphorus chemists have been interested in synthesizing low coordinated phosphorus compounds and in studying them in solution at temperatures rarely above 300 °C. As a matter of fact there are few reports on the behaviour of dicoordinated phosphorus molecules at temperatures above 500 °C under low pressure. Another interesting point is that such a study would allow to assess the correla- tion between mass spectral processes and thermal ones.
Journal of The Chemical Society-perkin Transactions 1 | 1977
L. Lopez; J. Barrans
The reactions of tris(dimethylamino)phosphine with amide oximes gave three types of compound, depending on the amide oxime substituents and the temperature: N2-[bis(dimethylamino)phosphinoyl]amidines (1), 4,6-disubstituted 2,5-dihydro-1,3,5,2-triazaphosphorine 2-oxides (2), and 3-dialkylamino-1-dimethylamino-1H-2,1-benzazaphosphole 2-oxides (3). With unsubstituted amide oximes only compounds (1) were formed at room temperature; at 80 °C a 1 : 1 mixture of (1) and (2) was obtained. Compounds (3) were obtained only with N-alkylbenzamide oximes. The formation of compounds (1)–(3) can be explained in terms of an unstable CN–O–PIII intermediate. 31P CIDNP effects were observed during the formation of compounds (3), in support of a radical mechanism. 1H N.m.r. and i.r. data are discussed.