Diels-Alder reactions in chloroaluminate ionic liquids: acceleration and selectivity enhancement

Ionic liquids. Green solvents for the future

“…One of the key benefits of this is that the ionic liquid and catalyst can be recycled and reused after solvent extraction or direct distillation of the product from the ionic liquid. The reaction has also been carried out in chloroaluminate(III) ionic liquids, but the moisture sensitivity of these systems is a major disadvantage [35].…”

Silica-supported chlorometallate(iii) ionic liquids as recyclable catalysts for Diels–Alder reaction under solventless conditions

“…A range of ionic liquids have also been tested as catalysts for Diels-Alder reaction; 4 the most active were Lewis acidic chloroaluminate(III) systems. 5,6,7 Chlorometallate ionic liquids are synthesised by the reaction of a metal halide with an organic halide salt, at various molar ratios, typically reported as molar ratio of the metal halide component,  MClx  When metal halide is used in excess ( MClx > 0.50), oligonuclear, Lewis acidic anions are formed. 8 An ionic liquid based on 1-ethyl-3-methylimidazolium chloride and a slight excess of aluminium chloride(III), [C 2 mim]Cl-AlCl 3 ;  AlCl3 = 0.51 was used as both solvent and catalyst for cycloaddition of cyclopentadiene to methyl acrylate.…”

“…However, the chloroaluminate(III) ionic liquid was used in a large excess. 5 In addition, chloroindate(III) 9 chlorozincate(II) and chlorostannate(II) ionic liquids were found to be active catalyst for the Diels-Alder reaction. 10,11 There are still some challenges to achieve, like application of catalytic amounts of ionic liquids and lowering reaction times.…”

Preparation of α-Bromoketones and Thiazoles from Ketones with NBS and Thioamides in Ionic Liquids

“…Ionic liquids offer interesting and useful features that are advantageous to organic reactions such as negligible vapor pressure, nonflammability, high thermal stability, and easy reusability. In this regard, ionic liquids have been successfully used in the Friedel-Crafts reaction [31][32][33], hydrogenation [34][35][36], Diels-Alder reactions [37][38][39], Mizoroki-Heck, Suzuki-Miyaura, Sonogashira, and olefin metathesis reactions [40][41][42][43][44], Michael additions [45], oxidation [46][47][48][49][50][51][52][53][54], condensation reaction [55][56][57][58][59], formation of imines [60], 1,2-rearrangement [61], esterification of carboxylic acids and carboxylates [62][63][64][65], Williamson ether synthesis [66][67][68][69][70][71][72], and the Grignard reaction [73,74]. We have reported efficient methods for the esterification of carboxylic acids and phosphonic acids with trialkyl orthoacetate in ionic liquid <...>…”