title: A solid-supported organocatalyst for continuous-flow enantioselective aldol reactions.
abstract: Asymmetric aldol reactions catalyzed by a novel polystyrene-immobilized proline derivative occur in short reaction times with excellent diastereo- and enantioselectivity. The catalyst can be recovered by simple filtration and shows very high reusability. The high activity depicted by the supported catalyst and its chemical and mechanical stability have allowed its application in packed-bed reactors for continuous flow processing. This system can produce enantio- and diastereomerically pure aldol adducts under continuous flow conditions with a residence time of 26 min. Furthermore, the reactor allowed processing of four different aldol products in sequence without any decrease in both catalytic activity and optical purity. The effective catalyst loading could be reduced to 1.6% (six-fold reduction of catalyst loading compared to the corresponding batch process).
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Tarragona, Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Ayats
authors.forename: Andrea H
authors.initials: AH
authors.lastname: Henseler
authors.forename: Miquel A
authors.initials: MA
authors.lastname: Pericàs
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D007659:Ketones / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000447:Aldehydes; D007659:Ketones; D011137:Polystyrenes; D011392:Proline