Polymer-immobilized pyrrolidine-based chiral ionic liquids as recyclable organocatalysts for asymmetric Michael additions to nitrostyrenes under solvent-free reaction conditions

A polymer immobilized pyrrolidine-based chiral ionic liquid 5a was synthesized and was found to be a highly efficient catalyst for the Michael additions of ketones and aldehydes to nitrostyrenes, which afforded the corresponding adducts in good yields (up to 97%), excellent enantioselectivities (up to > 99 % ee) and high diastereoselectivities (up to > 99:1 dr) under solvent-free reaction conditions. In addition, the catalyst 5a could be reused at least eight times without a significant loss of its catalytic activity and stereoselectivity.