The role of neutral anions in ionic liquid as solvent media for the reactivity and stereoselectivity towards asymmetric Michael addition reaction of n-pentanal with B-nitrostryrene catalyzed by L-Proline

• Main Authors: M. Omar, Emmy, A. Rahman, Mohd Basyaruddin, Ni, Bukuo, Headley, Allan D.
• Format: Article
• Language: English
• Published: Wiley-VCH Verlag 2019
• Online Access: http://psasir.upm.edu.my/id/eprint/82592/1/The%20role%20of%20neutral.pdf; http://psasir.upm.edu.my/id/eprint/82592/

Michael addition reactions of n-pentanal with ß-nitrostyrene in achiral and chiral ionic liquids catalyzed by l-proline were studied. Results indicate anion plays an important role as weak coordination properties in the reactivity and stereoselectivity towards Michael product. 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]) ionic liquid was found to be the best solvent media with a high yield (up to 90%) and a high diastereomeric ratio (syn/anti: 91/9), with moderate enantioselectivity (38% ee) among ten ionic liquids tested. The ionic liquid has been reusable over five numbers of cycles.