Chiral Ionic Liquids Bearing <i>O</i>‐Silylated α,α‐Diphenyl (<i>S</i>)‐ or (<i>R</i>)‐Prolinol Units: Recoverable Organocatalysts for Asymmetric Michael Addition of Nitroalkanes to α,β‐Enals

Abstract

Abstract Chiral ionic liquids bearing O ‐silylated α,α‐diphenyl ( S )‐ or ( R )‐prolinol units tagged to the imidazolium cation were synthesized and their activity as catalysts in the Michael addition of nitroalkanes to α,β‐unsaturated aldehydes was evaluated. Respective ( S ) or ( R ) adducts were obtained in the reactions in high yields (up to 95 %) and with high enantioselectivity (up to 99 % ee ). Remarkably, the immobilized organocatalysts could be used five times without any decrease in product yields or ee values. ( R )‐Michael adducts could be easily transformed into the most active ( R ) enantiomers of medications Phenibut, Baclofen, and Rolipram for the treatment of CNS disorders.