Abstract
Background: Low toxicity ionic liquids (ILs) have shown a wide range of applications in material chemistry, synthetic chemistry, and green chemistry. They can be considered as 'green' alternatives to the conventional solvents, as their unique properties can offer additional benefits. In our previous reports, we have shown that such ILs can be used as reaction media in hydrogenation, carbonyl-ene reactions, and Brønsted acid catalyzed reactions.
Methods: Low toxicity ILs are prepared by a short synthesis. The palladium based catalyst bearing an asymmetric ligand is immobilized in these ILs. This ‘green’ catalytic system is employed for enantioselective Tsuji-Trost reactions. For comparison, several reactions are run in conventional solvents.
Results: The reactions in ILs provide good to excellent enantiomeric excess, however, low yields are obtained compared to the conventional solvents. The catalytic system is recyclable.
Conclusion: Conventional solvent (DMSO) is proved to be superior to our ILs, however, the results in our ILs are an improvement over [bmim] ILs. The low yields are attributed to high viscosity of the ILs, and we propose can be resolved by tuning the viscosity of the IL by anion exchange.
Keywords: Enantioselectivity, ionic liquids, Pd-catalysis, recyclable, Tsuji-Trost reaction.
Graphical Abstract
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