Immobilization of Functionalized epi-Cinchonine Organocatalysts on Controlled Porous Glass-Beads: Applications in Batch and Continuous Flow

A well-known Squaramide-Cinchonine organocatalyst was immobilized in a controlled way onto three types of commercial porous glass beads EziGTM (EziG OPAL, EziG Amber and EziG Coral) and applied in asymmetric Michael reactions. The performance of the immobilized catalysts was evaluated under batch and continuous flow conditions showing promising results in both approaches. In batch reactions, 0.8 and 1.6 mol% of the immobilized cinchonine-squaramide provided the products with excellent yields (up to 99%) and enantioselectivities (up to 99% ee). These excellent results were also verified in the case of continuous flow reactions, where also 0.8 and 1.6 mol% of the catalyst immobilized onto the glass beads afforded the product with extraordinary yields (up to 99%) and very high enantioselectivities (up to 97% ee). The immobilized catalysts could be recycled (up to 7 cycles) using both approaches.