Calixarene-proline functionalized iron oxide magnetite nanoparticles (Calix-Pro-MN): An efficient recyclable organocatalyst for asymmetric aldol reaction in water

• Calix[4]arene proline-grafted magnetic nanoparticles are becoming hot topic.
• A novel calix[4]arene proline appended magnetic nanoparticles has been synthesized.
• Calix-Pro-MN can catalyze aldol reactions between cyclohexanone and aromatic aldehydes.
• High enantioselectivities (up to 93% ee) and diastereoselectivities (up to 97:3) were obtained.
• The catalyst is easily separated using an external magnetic field and reused for several times.

Calix[4]arene-based chiral organocatalyst derived from L-proline supported onto well-defined (15 ± 3 nm) magnetic Fe3O4 nanoparticles was used as a highly active, recoverable, and reusable catalyst for the asymmetric aldol reaction in water without need for organic solvents. The chiral organocatalyst showed high catalytic activity (up to 94%), enantioselectivity (up to 93%) and diastereoselectivity (up to 97:3) for the reaction between cyclohexanone and aromatic aldehydes. The catalyst could easily separated using an external magnetic field and reused for several times without any significant loss of activity.

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