A chiral organocatalytic polymer-based monolithic reactorElectronic supplementary information (ESI) available: Synthetic procedures and 1H NMR, 13C NMR, and IR spectra of new compounds. Preparation, analysis and characterization of polymer-supported chiral catalysts. NMR and HPLC traces of the stereoselective reaction products. See DOI: 10.1039/c4gc00031e

• Main Authors: Chiroli, Valerio, Benaglia, Maurizio, Puglisi, Alessandra, Porta, Riccardo, Jumde, Ravindra P, Mandoli, Alessandro
• Format: Article
• Language: English
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/c4gc00031e

Radical copolymerisation of divinylbenzene and a properly modified enantiomerically pure imidazolidinone inside a stainless steel column in the presence of dodecanol and toluene as porogens afforded the first example of a chiral organocatalyst immobilized onto a monolithic reactor. Organocatalyzed cycloadditions between cyclopentadiene and cinnamic aldehyde were performed under continuous-flow conditions; by optimizing the experimental set up, excellent enantioselectivities (90% ee at 25 °C) and high productivities (higher than 330) were obtained, thus showing that a catalytic reactor may work efficiently to continuously produce enantiomerically enriched compounds. The same catalytic reactor was also employed to carry out three different stereoselective transformations in continuo , sequentially, inside the chiral column (Diels-Alder, 1,3-dipolar nitrone-olefin cycloaddition, and Friedel-Crafts alkylation); excellent results were obtained in the case of the former two reactions (up to 99% yield, 93% ee and 71% yield, 90% ee, at 25 °C, respectively). In addition to simplify the product recovery, the monolithic reactor performed better than the same supported organocatalyst in a stirred flask and could be kept working continuously for more than 8 days. An organocatalytic polymer-based monolithic reactor was employed in stereoselective transformations in flow; three different reactions in a row have been catalyzed in continuo (up to 93% ee), in a system that worked 200 hours, with a productivity higher than 330.