A Fast-Initiating Ionically Tagged Ruthenium Complex: A Robust Supported Pre-catalyst for Batch-Process and Continuous-Flow Olefin Metathesis

作者:Borre Etienne; Rouen Mathieu; Laurent Isabelle; Magrez Magaly; Caijo Frederic; Crevisy Christophe; Solodenko Wladimir; Toupet Loic; Frankfurter Rene; Vogt Carla; Kirschning Andreas*; Mauduit Marc
来源:Chemistry - A European Journal, 2012, 18(51): 16369-16382.
DOI:10.1002/chem.201201589

摘要

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 oxazinebenzylidene 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.

  • 出版日期2012-12