Ionic liquids - deanol derivatives as the Diels-Alder reaction solvents (original) (raw)
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Catalysis Letters, 2008
Phosphonium ionic liquid (IL)-trihexyl-tetradecylphosphonium bis(trifluoromethylsulfonyl)imide, has been tested as the medium in the Diels-Alder reaction between cyclopentadiene and dienophiles from the group of a,b-unsaturated esters, aldehydes and ketones. Catalytic activities of a few metal chlorides, triflates and bis-triflimides in this reaction have been compared. The recycling of the catalyst with phosphonium IL was studied.
Central European Journal of Chemistry, 2011
A comparative study of the Diels-Alder reactions between cyclopentadiene (1) and dienophiles (2 a–c) in N-hexylpyridinium bis(trifluoromethylsulfonyl)imide in a temperature range of 20–45°C is reported. The reaction rate constants and activation energies were calculated. Moreover, the catalytic systems based on N-hexylpyridinium bis(trifluoromethylsulfonyl)imide and Lewis acids were tested as a reaction media to perform the Diels-Alder reaction. Yb, Y, Mg, Zn triflates and chlorides (0.005 to 0.1 mmol) were used as catalysts. The recycling of catalytic system consisted of YCl3 and ionic liquid was performed.
Catalysis Letters, 2011
The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels-Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr 1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined.
Advanced Synthesis & Catalysis, 2004
Various imidazolium ionic liquids such as [Bmim]PF 6 , [Bmim]SbF 6 , [Bmim]OTf and [Bmim]BF 4 were screened for recycling an organic catalyst [(5S)-5-benzyl-2,2,3-trimethylimidazolidin-4-one (1)] for asymmetric Diels±Alder reactions. Good yields and enantioselectivies (up to 85% yield and 93% ee) were obtained from reactions in [Bmim]PF 6 or [Bmim]SbF 6 . However, reactions in [Bmim]OTf or [Bmim]BF 4 gave racemic products in low yields. Isolation of the products by simple extraction using diethyl ether allowed recycling of the ionic liquid containing the immobilized catalyst in subsequent reactions without significant decrease of yields and enantioselectivities.
Diels–Alder reaction in protic ionic liquids
Tetrahedron Letters, 2006
Protic imidazolium ionic liquids have been tested as reaction media in the Diels-Alder reaction between cyclopentadiene and two dienophiles (dimethyl maleate and methyl acrylate). Good conversions and endo/exo selectivities were achieved. The activation of the dienophile by hydrogen bonding with protic imidazolium ILs was demonstrated.