Synthesis of New Functionalized Chiral Ionic Liquid and Its Organocatalytic Asymmetric Michael Addition

Abstract

A novel recyclable functionalized chiral ionic liquid has been developed to promote asymmetric Michael additions of cyclohexanone to both aryl and alkyl nitroolefins in the presence of 20 mol% of organocatalyst 4 in MeOH. The process affords synthetically valuable chiral products in good yields (up to 93%) and high enantioselectivities (up to 92%). The chiral ionic liquid could be easily reused six times without remarkable decrease in yields and enantioselectivities.

GRAPHICAL ABSTRACT

Keywords:

• Asymmetric Michael addition
• chiral ionic liquid
• recyclable

ACKNOWLEDGMENT

This work was supported by the Foundation of Chang Zhou University (Nos. ZMF1002130 and ZMF1002100).

Notes

^a Unless otherwise noted, all reactions were carried out in solvent (100 µl) using 5 (0.0196 g, 2 eq) and 6a (0.0149 g, 1 eq) in the presence of 20 mol% of 4.

^b Isolated yields.

^c The trans/cis ratios are determined by ¹H NMR.

^d Determined by HPLC using Chiracel AD-H/AS-H column.

^a Unless otherwise noted, all reactions were carried out in solvent (100 µl) using 5 (0.0196 g, 2 eq) and 6 (0.0149 g, 1 eq) in the presence of 20 mol% of 4.

^b Isolated yields.

^c The trans/cis ratios are determined by ¹H NMR.

^d Determined by HPLC using Chiracel AD-H/AS-H column.

^a Isolated yields.

^b Determined by HPLC using Chiracel OD-H column.