Synthesis of new chiral ionic liquids from natural acids and their applications in enantioselective Michael addition

Wang, Zhiming; Wang, Qiang; Bao, Weiliang

doi:10.1016/j.tetlet.2005.04.134

Cited by 118 publications

(40 citation statements)

References 25 publications

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“…8 The preparation and characterization of a variety of ether-functionalized imidazolium RTILs are reported in the literature. [9][10][11][12] Applications of these are found in the fields of molecular-recognition, 13 transition-metal catalysis, 14 biocatalysis, 15 carbohydrate/nucleoside chemistry, 16,17 anti-microbial activities, 18 metal extraction, 19 liquid-phase organic synthesis, 20 polymer chemistry, 21 organic synthesis, 22 self-organization 23 and lubricants. 24 Understanding how structural changes affect physicochemical properties is of great importance for the preparation of task-specific RTILs.…”

Section: Introductionmentioning

confidence: 99%

Preparation, cation-anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids

Schrekker

Silva

Gelesky

et al. 2008

J. Braz. Chem. Soc.

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Uma série de líquidos iônicos 1-alquil éter (e 1-alquil)-3-metilimidazólio 2-4 ([C x O y MIm] + [Ânion] ou [C x MIm] + [Ânion] , onde MIm = 3-metilimidazólio; C x O y = 1-alquil éter, C 7 O 3 = -(CH 2 ) 2 O(CH 2 ) 2 O(CH 2 ) 2 OCH 3 (A), C 3 O 1 = -(CH 2 ) 2 OCH 3 (B); C x = 1-alquil, C 10 = C 10 H 21 (C), C 4 = C 4 H 9 (D); e [Ânion] = H 3 CSO 3 (2), BF 4 (3) ou PF 6 (4)) foram preparados e caracterizados. A força da ligação de hidrogênio entre o cátion e o ânion dos líquidos iônicos 2-4 depende principalmente do ânion e diminui na ordem H 3 CSO 3 > BF 4 > PF 6 . Todos os líquidos iônicos metanosulfonatos 2 possuem uma forte desblindagem para o próton H 2 do ciclo imidazólio. Os líquidos iônicos funcionalizados com um grupo 1-alquil éter mostram densidades mais altas em comparação com seus equivalentes do grupo 1-alquil. Os sais 2a-b, 3a-d e 4a-b são líquidos iônicos à temperatura ambiente. E, todos os líquidos iônicos 1-alquil éter funcionalizados (exceto 4b) são completamente amorfos. As maiores faixas líquidas foram obtidas com os líquidos iônicos tetrafluoroborato devido as suas solidificações a temperaturas baixas e excelente estabilidade térmica. Estes dados fornecem informações importantes para o entendimento sobre possíveis aplicações e a preparação de líquidos iônicos com tarefas específicas.A set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium ionic liquids 2-4 ([C x O y MIm] + [Anion] or [C x MIm] + [Anion] , where MIm = 3-methylimidazolium; C x O y = 1-alkyl ether, C 7 O 3 = -(CH 2 ) 2 O(CH 2 ) 2 O(CH 2 ) 2 OCH 3 (A), C 3 O 1 = -(CH 2 ) 2 OCH 3 (B); C x = 1-alkyl, C 10 = C 10 H 21 (C), C 4 = C 4 H 9 (D); and [Anion] = H 3 CSO 3 (2), BF 4 (3) or PF 6 (4)) was prepared and characterized. The cation-anion hydrogen bonding strength showed to be mainly anion dependent and decreased in the order H 3 CSO 3 > BF 4 > PF 6 . All methanesulfonate ionic liquids 2 possessed a strongly deshielded H 2 imidazolium ring proton. 1-Alkyl ether functionalized ionic liquids showed higher densities in comparison to their 1-alkyl equivalents. The salts 2a-b, 3a-d and 4a-b are room-temperature ionic liquids. All 1-alkyl ether functionalized ionic liquids (except 4b) are completely amorphous. The widest liquid ranges were obtained with the tetrafluoroborate ionic liquids due to their late solidification and excellent thermal stability. These data provide important information for the understanding of their application scope and the preparation of task-specific ionic liquids.Keywords: imidazolium ionic liquids, ether-functionalized, hydrogen bonding, physicochemical properties, task-specific IntroductionRoom-temperature ionic liquids (RTILs), ionic salts that melt at and below ambient temperature, typically comprise of an organic cation and an organic or inorganic anion. The class of imidazolium RTILs is used in a wide variety of applications due to their attractive physical and chemical properties, 1-3 which include: air and moisture stability, low flammability, thermal stability, a neglectable vapor pressure, bei...

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Section: Introductionmentioning

confidence: 99%

Preparation, cation-anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids

Schrekker

Silva

Gelesky

et al. 2008

J. Braz. Chem. Soc.

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“…Previously works on CIL-catalyzed Michael additions with organic co-solvents reported much lower enantiomeric excesses (< 15% [42], and < 25% [43],). More recent examples for this reaction, can be found elsewhere [44].…”

Section: -44mentioning

confidence: 87%

Application of Chiral Ionic Liquids for Asymmetric Induction in Catalysis

Prechtl¹,

Scholten²,

Neto³

et al. 2009

COC

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“…Scheme 14. The group of Bao investigated the influence of ethyl (S)-(-)-lactate and diethyl (S)-(+)-tartrate-derived CILs on asymmetric Michael addition of diethyl malonate to chalcone (Scheme 15). [32] Excellent yields in the range of 90 to 96 % were obtained in the presence of a 10-fold excess of CIL using potassium carbonate as base and toluene as cosolvent. The lactate-derived CIL 19 proved to be superior, however, only modest enantiomeric excess of 25 % was ob-served, whereas the tartrate derivative only gave an enantiomeric excess of 10 %.…”

Section: Asymmetric Michael Additionmentioning

confidence: 99%

Applications of Chiral Ionic Liquids

2008

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Despite the rapid growth in chiral ionic liquid (CIL) research, successful applications remained hidden for some time, but are increasing fast nowadays. The major part of this review deals with the use of CILs as solvents, catalysts or ligands in asymmetric synthesis. Chiral recognition abilities in spectroscopic techniques such as NMR, NIR or fluorescence spectroscopy are discussed as well as the application of CILs for separation in chromatography. In this review, we focus entirely on the applications of CILs; publications dealing with design and synthesis of CILs only are not mentioned. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Synthesis of new chiral ionic liquids from natural acids and their applications in enantioselective Michael addition

Cited by 118 publications

References 25 publications

Preparation, cation-anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids

Preparation, cation-anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids

Application of Chiral Ionic Liquids for Asymmetric Induction in Catalysis

Applications of Chiral Ionic Liquids

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