Enantioselective cyclopropanation reactions in ionic liquids

Asymmetric cyclopropanation in ionic liquids: effect of anion and impurities

“…18 During the course of our work the use of imidazolium based ionic liquids for immobilisation of bis(oxazoline) copper catalysts and their use in cyclopropanation of styrene has been reported and it was found that the nature of the cation and anion of the ionic liquid effected the performance of the catalysts. 19 However, our results differ from those published particularly in the case of ionic liquids containing the BF 4 anion. We report here the copper bis(oxazoline) catalysed asymmetric cyclopropanation of styrene in four different ionic liquids, attempts to reuse the catalyst, and a reinterpretation of some of the results described previously.…”

“…A reduction in the stereoselectivity in [EMIM][NTf 2 ] (EMIM ¼ 1-ethyl-3-methylimidazolium) was noted previously. 19 However, the yields and enantioselectivities are significantly higher than those (3-50% yield, 0-85% ee) observed previously 19 19 Seddon et al have shown, at least for chloride salts that this procedure is inefficient at removing all the unreacted dialkylimidazolium halide. 21 We have ex- To optimise the yield we wished to minimise the levels of diethyl maleate and fumarate formed by carbene dimerisation.…”

Recent Advances in Catalysis Over Mesoporous Molecular Sieves

“…In a subsequent paper, more extensive studies [162] of different silica supports (MCM-48, SBA-15 and amorphous silica) were carried out. Lewis acid promoted reactions such as Diels-Alder reactions, Ene reactions, Mukaiyama-aldol reactions and other allyl substitutions, oxidation and reductions were reviewed [158].…”

Reaction Rates as a Function of Scale within Ionic Liquids: Microscale in Droplet Microreactors versus Macroscale Reactions in the Case of the Grieco Three‐Component Condensation Reaction

“…These reagents have already been successfully used for peptides synthesis, [15,16] multicomponent reactions, [12,13,17] pericyclic reactions, such as cycloadditions, [14,18] and transition metal-catalysed reactions. [19] Recently, labs-on-a-chip (LOC) dedicated to chemical applications have attracted growing interest. [20][21][22][23][24] Indeed, compared to a traditional batch reaction, miniaturised systems allow reducing the consumption of reagents, faster optimisation of reactions and production of the desired products usually in greater yield and purity.…”