title: A fast-initiating ionically tagged ruthenium complex: a robust supported pre-catalyst for batch-process and continuous-flow olefin metathesis.
abstract: In this study, a new pyridinium-tagged Ru complex was designed and anchored onto sulfonated silica, thereby forming a robust and highly active supported olefin-metathesis pre-catalyst for applications under batch and continuous-flow conditions. The involvement of an oxazine-benzylidene ligand allowed the reactivity of the formed Ru pre-catalyst to be efficiently controlled through both steric and electronic activation. The oxazine scaffold facilitated the introduction of the pyridinium tag, thereby affording the corresponding cationic pre-catalyst in good yield. Excellent activities in ring-closing (RCM), cross (CM), and enyne metathesis were observed with only 0.5 mol % loading of the pre-catalyst. When this powerful pre-catalyst was immobilized onto a silica-based cationic-exchange resin, a versatile catalytically active material for batch reactions was generated that also served as fixed-bed material for flow reactors. This system could be reused at 1 mol % loading to afford metathesis products in high purity with very low ruthenium contamination under batch conditions (below 5 ppm). Scavenging procedures for both batch and flow processes were conducted, which led to a lowering of the ruthenium content to as little as one tenth of the original values.
authors.affiliation: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Av. du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Borré
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rouen
authors.forename: Isabelle
authors.initials: I
authors.lastname: Laurent
authors.forename: Magaly
authors.initials: M
authors.lastname: Magrez
authors.forename: Fréderic
authors.initials: F
authors.lastname: Caijo
authors.forename: Christophe
authors.initials: C
authors.lastname: Crévisy
authors.forename: Wladimir
authors.initials: W
authors.lastname: Solodenko
authors.forename: Loic
authors.initials: L
authors.lastname: Toupet
authors.forename: René
authors.initials: R
authors.lastname: Frankfurter
authors.forename: Carla
authors.initials: C
authors.lastname: Vogt
authors.forename: Andreas
authors.initials: A
authors.lastname: Kirschning
authors.forename: Marc
authors.initials: M
authors.lastname: Mauduit