Ester-Containing Imidazolium-Type Ionic Liquid Crystals Derived from Bio-based Fatty Alcohols

The need to take into account the life cycle of ionic liquids (ILs), from the sourcing of the raw materials involved in their synthesis to their disposal and degradation, has become paramount in the design of new IL-type molecular structures. In the case of 1-alkyl-3-methylimidazolium salts, one of the prominent IL families, there is an increasing demand for synthetic methods involving (i) substitution of the petro-based alkyl derivatives by readily available bio-sourced surrogates and (ii) functionalization of the alkyl tail with heterofunctional groups enabling the (bio)degradation of ILs after use. Herein, a straightforward and industrially viable synthesis of lipidic imidazolium salts is reported, starting from different bio-sourced fatty alcohols, including oleic, stearyl, and lauryl alcohols. This procedure is based on the acrylation of fatty alcohols, followed by the aza-Michael addition of the imidazole group onto the acrylate moiety. Subsequent quaternization, using either methyl iodide or methyl tosylate, provides a library of 1-alkylpropionate-3-methylimidazolium salts with various alkyl chain lengths (C18, C12, and C11) and incorporating different types of counteranions (iodide, tosylate, and tetrafluoroborate). These ester-containing analogues of classical 1-alkyl-3-methylimidazolium salts are all ILs, that is, with a melting point below 100 °C. In addition, most of them exhibit a liquid-crystal behavior and can be referred to as IL crystals (ILCs). The thermal stability, as well as the phase transitions of these ILs, has been investigated by thermogravimetric analysis, as well as differential scanning calorimetry, respectively, while the molecular structure into the crystalline phase and the mesophase is studied by X-ray scattering. Interestingly, ILCs featuring unsaturated alkyl tails exhibit a low melting point, close to room temperature, and the presence of the ester function is shown to provide an enhanced stabilization of the mesophase

Nouveaux procédés de synthèse d hétérocycles azotés par carbométallation intramoléculaire d ynamides

Les différents projets réalisés durant mes trois années de thèse sont tous axés sur le développement de nouvelles méthodes de synthèse d hétérocycles azotés via une approche unifiée basée sur l utilisation de réactions de carbométallation intramoléculaires d ynamides. Ces composés uniques dont la chimie a connu un développement record ces dernières années, notamment pour l'inclusion de groupes fonctionnels azotés au sein de molécules organiques, sont en train d émerger comme des briques élémentaires particulièrement utiles et polyvalentes en synthèse organique. Nous avons pu mettre à profit leur réactivité remarquable pour la mise au point de nouveaux procédés de synthèse hétérocycliques basés sur différentes réactions de carbométallation intramoléculaires au départ d ynamides convenablement substitutés. Ainsi, nous avons pu mettre au point de nouvelles voies d accès à des dihydropyridines, des pyridines ou des indoles par réactions de carbolithiation et carbocupration intramoléculaires d ynamides, ces procédés permettant un accès original et efficaces à ces différents systèmes hétérocycliques, ce qui a pu notamment être mis en valeur avec la synthèse formelle d une molécule bioactive : le Sarizotan. Ces travaux devraient contribuer à étendre l'utilité synthétique des ynamides ainsi que des réactions de carbométallation intramoléculaires en synthèse organique.The research projects that I have been involved during my PhD are all focused on the development of new processes for the synthesis of nitrogen heterocycles based on a unified approach relying on the use of intramolecular carbometallation reactions from ynamides. These unique molecules, whose chemistry has been under intense investigation during the last decade, notably for the inclusion of nitrogen-based functional groups into organic molecules, are emerging as useful and versatile building blocks in organic synthesis. Capitalizing on their unique reactivity, we have been able to design new processes in heterocyclic chemistry based on various carbometallation reactions starting from conveniently substituted ynamides. Indeed, we developed new routes to dihydropyridines, pyridines and indoles by intramolecular carbolithiation or carbocupration of ynamides. These new reactions allow for a straightforward and original entry to these various heterocyclic systems, which could be highlighted by a formal synthesis of a bioactive compound: Sarizotan. All together, this work should contribute to further expand the synthetic utility of ynamides as well as intramolecular carbometallation reactions in organic synthesis.VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceTunisiaFRT

Ester-Containing Imidazolium-Type Ionic Liquid Crystals Derived from Bio-based Fatty Alcohols

International audienceThe need to take into account the life cycle of ionic liquids (ILs), from the sourcing of the raw materials involved in their synthesis to their disposal and degradation, has become paramount in the design of new IL-type molecular structures. In the case of 1-alkyl-3-methylimidazolium salts, one of the prominent IL families, there is an increasing demand for synthetic methods involving (i) substitution of the petro-based alkyl derivatives by readily available bio-sourced surrogates and (ii) functionalization of the alkyl tail with heterofunctional groups enabling the (bio)degradation of ILs after use. Herein, a straightforward and industrially viable synthesis of lipidic imidazolium salts is reported, starting from different bio-sourced fatty alcohols, including oleic, stearyl, and lauryl alcohols. This procedure is based on the acrylation of fatty alcohols, followed by the aza-Michael addition of the imidazole group onto the acrylate moiety. Subsequent quaternization, using either methyl iodide or methyl tosylate, provides a library of 1-alkylpropionate-3-methylimidazolium salts with various alkyl chain lengths (C18, C12, and C11) and incorporating different types of counteranions (iodide, tosylate, and tetrafluoroborate). These ester-containing analogues of classical 1-alkyl-3-methylimidazolium salts are all ILs, that is, with a melting point below 100 °C. In addition, most of them exhibit a liquid-crystal behavior and can be referred to as IL crystals (ILCs). The thermal stability, as well as the phase transitions of these ILs, has been investigated by thermogravimetric analysis, as well as differential scanning calorimetry, respectively, while the molecular structure into the crystalline phase and the mesophase is studied by X-ray scattering. Interestingly, ILCs featuring unsaturated alkyl tails exhibit a low melting point, close to room temperature, and the presence of the ester function is shown to provide an enhanced stabilization of the mesophase

Intramolecular Carbocupration of N‑Aryl-ynamides: A Modular Indole Synthesis

A modular indole synthesis based on an intramolecular 5-endo-dig carbocupration starting from readily available N-aryl-ynamides is reported. A variety of ynamides are converted to indoles in moderate to good yields and with varying substitution pattern on the indole ring. This further extends the synthetic utility of ynamides in organic synthesis and provides additional insights on the use of intramolecular carbometalation reactions.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

De Novo Synthesis of 1,4-Dihydropyridines and Pyridines

An efficient and general method for the synthesis of 1,4-dihydropyridines and pyridines based on a lithiation/isomerization/intramolecular carbolithiation sequence is reported. This procedure provides an efficient, divergent, and straightforward entry to a wide range of polysubstituted dihydropyridines and pyridines starting from readily available <i>N</i>-allyl-ynamides

Intramolecular Carbocupration of <i>N</i>‑Aryl-ynamides: A Modular Indole Synthesis

A modular indole synthesis based on an intramolecular 5-<i>endo</i>-<i>dig</i> carbocupration starting from readily available <i>N</i>-aryl-ynamides is reported. A variety of ynamides are converted to indoles in moderate to good yields and with varying substitution pattern on the indole ring. This further extends the synthetic utility of ynamides in organic synthesis and provides additional insights on the use of intramolecular carbometalation reactions

Erratum to “A mild method for the replacement of a hydroxyl group by halogen: 2. unified procedure and stereochemical studies” Tetrahedron 76 (37) (11 September 2020) 131441

The publisher regrets that the below dedication to Prof. Richard. Taylor was not included in the above article. “Dedicated to Prof. Richard. Taylor for his superb contribution to organic chemistry as researcher and editor.” The publisher would like to apologise for any inconvenience caused

A mild method for the replacement of a hydroxyl group by halogen. 2, Unified procedure and stereochemical studies

N,N-Dimethyl- and N,N-diisopropyl-1-halo-2-methyl-l-propenylamines are readily available reagents for the mild deoxyhalogenation of alcohols and hydroxyacids. In this study we showed that the reactivity of the reagents can be tuned by varying the size of the alkyl groups on the reagents: the replacement of methyl by isopropyl groups led to a significant increase of reactivity. We then described a unified procedure for all deoxyhalogenations using the readily available α-chloroenamines as reagents with (bromination, iodination) or without (chlorination) an alkaline bromide or iodide. Finally, we showed that deoxyhalogenation reactions of secondary alcohols were highly stereospecific and generally occurred with inversion of configuration

A Journey in the Chemistry of Ynamides: From Synthesis to Applications

info:eu-repo/semantics/publishe

A Journey in the Chemistry of Ynamides: From Synthesis to Applications

Due to their combined stability and peculiar reactivity, ynamides have emerged as remarkably useful building blocks for chemical synthesis. The development of general and robust methods for their preparation resulted in a massive interest for their chemistry. This notably resulted in the development of incredibly efficient processes starting from these building blocks which also recently found various applications in medicinal chemistry and natural product synthesis. Our efforts and contributions to the chemistry of ynamides, for which we have developed several reactions both for their preparation and for their use in synthesis, are overviewed in this highlight review.SCOPUS: re.jinfo:eu-repo/semantics/publishe