L-Hydroxyproline Immobilized on MCM-41 by Ionic Liquid as a Hetero - geneous Organocatalyst for Direct Asymmetric Aldol Addition

A new heterogenized silica-based organocatalyst was prepared via anion exchange of imidazolium ionic liquid with L– hydroxyproline material. This was evaluated as a heterogenous organocatalyst for the asymmetric aldol reaction of nitrobenzaldehydes, cyclohexanone and cyclopentanone by performing the reaction under different conditions by using several solvents and reaction temperatures. Excellent isolated yields of the aldol products of up to %90 were achieved. In addition, excellent selectivity (ee up to %98) was obtained. In one case, dr reached up to > 99:1. Keywords: Asymmetric synthesis, imidazolium ionic liquid, hydroxy proline, aldol addition, organocatalyst, MCM-41.