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Hacan Khaled Awad

Associate professor
Chemistry - Biochemistry department - Section III - Tripoli
Speciality: Chemistry
Specific Speciality: Chimie Organique

Teaching 5 Taught Courses
Publications 7 publications
Haçan Hawad, Omar Bayh, Christophe Hoarau, Francois Trécourt, Guy Quéguiner, Francis Marsais Deprotonation of pyridine carboxamides using lithium magnesiates bases ELSEVIER 2008

Regioselective deprotonation of N-methyl- and tert-butylpyridine carboxamides using lithium magnesiates bases was achieved at room temperature avoiding nucleophilic addition on the pyridine molecule and auto-condensation of the arylmetal intermediates on the amide group was described. The hydrogen–magnesium exchange was evidenced using 1H NMR spectroscopy at room temperature and the reactivity of the lithium 2-, 3- and 4-carboxamidopyridinylmagnesiates complexes towards electrophiles and in cross-coupling reactions was studied. --------------------------------------------------------------------------------

Elodie Weymeels, Haçan Awad, Laurent Bischoff, Florence Mongin, , François Trécourt, Guy Quéguiner, , Francis Marsais On the deprotonation of 3,5-dichloropyridine using lithium bases: in situ infrared spectroscopic studies ELSEVIER 2005

Deprotonation of 3,5-dichloropyridine using LTMP and BuLi was monitored in real time by infrared spectroscopy. It appeared that the substrate was rapidly deprotonated. Transient structures between the substrate and the lithio derivative were detected. The absorbances recorded for the lithio derivative showed that the structures obtained using LTMP and BuLi were similar. When BuLi was used to deprotonate, a complete deuteration of the lithio derivative was noted upon quenching with D2O. The latter did not allow the quantification of the lithio derivative when LTMP was used, since only partial deuteration was observed. --------------------------------------------------------------------------------

Omar Bayh ,† Haçan Awad ,† Florence Mongin ,*†‡ Christophe Hoarau ,† Laurent Bischoff ,† François Trécourt ,† Guy Quéguiner ,† Francis Marsais ,† Fernando Blanco ,§ Belén Abarca ,§ and Rafael Ballesteros § Deprotonation of Benzoxazole and Oxazole Using Lithium Magnesates JOC 2005

The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways:  (1) the equilibration between the open and closed structures is faster than the trapping of the open isomers, and the closed isomers are more reactive than the open ones, or (2) the open isomers react with electrophiles in a intramolecular Passerini type reaction. The nonreactivity of the 2-(isocyano)enolate type structure toward anisaldehyde in the absence of lithium bromide makes the intramolecular Passerini type reaction more plausible.

Omar Bayh, Haçan Awad, Florence Mongina, , †, , Christophe Hoarau, François Trécourt, Guy Quéguiner, Francis Marsais, Fernando Blanco, Belén Abarca, Rafael Ballesteros Deprotonation of thiophenes using lithium magnesates ELSEVIER 2005

Thiophene was regioselectively deprotonated at C2 on treatment with 1/3 equiv of Bu3MgLi in THF at room temperature. The lithium arylmagnesate formed was either trapped with electrophiles or cross-coupled in a ‘one-pot’ procedure with aryl halides under palladium catalysis. 2-Chlorothiophene and 2-methoxythiophene were similarly deprotonated at C5 under the same reaction conditions. The enhancement of the reactivity of the base using TMEDA was evidenced using 1H NMR spectroscopy. --------------------------------------------------------------------------------

Florence Mongin, , , Aurélien Bucher, Jean Pierre Bazureau, Omar Bayh, Haçan Awad, François Trécourt Deprotonation of furans using lithium magnesates ELSEVIER 2005

Furan was deprotonated on treatment with 1/3 equiv of Bu3MgLi in THF at rt. The lithium arylmagnesate formed was either trapped with electrophiles or involved in a palladium-catalyzed cross-coupling reaction with 2-bromopyridine. The highly coordinated magnesate Bu4MgLi2 (1/3 equiv) proved to be a better deprotonating agent than Bu3MgLi; the monitoring of the reaction using NMR spectroscopy showed that the deprotonation of furan at rt required 2 h whereas the subsequent electrophilic trapping was instantaneous. The method was extended to benzofuran, allowing its functionalization at C2 in high yields. The deprotonation of 2-methylfuran and lithium furfurylalkoxide at C5 turned out to be difficult, requiring either long reaction times or higher temperatures. --------------------------------------------------------------------------------

Haçan Awad, Florence Mongin, François Trécourt, Guy Quéguiner, Francis Marsais, Fernando Blanco, Belén Abarca, Rafael Ballesteros Deprotonation of fluoro aromatics using lithium magnesates ELSEVIER 2004

3-Fluoropyridine was deprotonated on treatment with 1/3 equiv of Bu3MgLi in THF at −10 °C. The lithium arylmagnesate formed was either trapped with electrophiles or involved in a palladium-catalyzed cross-coupling reaction with 2-bromopyridine. The use of a less nucleophilic lithium-magnesium-dialkylamide, (TMP)3MgLi, allowed the reaction of 3-fluoroquinoline, giving the 2,2′-dimeric derivative. 2-Fluoropyridine and 2,6-difluoropyridine were deprotonated using 1/3 equiv of the highly coordinated magnesate Bu4MgLi2 in THF at −10 °C in the presence of a substoichiometric amount of 2,2,6,6-tetramethylpiperidine. 1,3-Difluorobenzene reacted similarly when treated with Bu3MgLi; the reactivity of the base proved to be enhanced by the presence of TMEDA.

Haçan Awad, Florence Mongin, , François Trécourt, Guy Quéguiner, Francis Marsais Deprotonation of chloropyridines using lithium magnesates ELSEVIER 2004

4-Chloropyridine was deprotonated on treatment with 1/3 equiv of the highly coordinated magnesate Bu3(TMP)MgLi2 in THF at −10 °C, as evidenced by trapping with I2. The use of Bu(TMP)2MgLi in Et2O allowed the reaction of 2-chloropyridine, giving the 3-functionalized derivative as the main product. Mixtures of 3- and 4-functionalized derivatives were obtained when 2,6-dichloropyridine was involved in the reaction. Performing the reaction on 3-chloropyridine with lithium magnesates in THF, either the 4,4′-dimer or the 4-iodo derivative was formed after quenching by I2, the former using 1/3 equiv of Bu2(TMP)MgLi and the latter using 1 equiv of (TMP)3MgLi. Similar results were observed with 3,5-dichloropyridine, 2,5-dichloropyridine and 3-chloro-2-fluoropyridine. 1,2-Migration of the lithium arylmagnesate formed by deprotonation was proposed to justify the dimers formation.