No abstract

We describe RCM reactions in the presence of a Hoveydatype catalyst covalently immobilized on different support materials. The performance of the catalyst was highly dependent on the nature of the support, and in some cases high levels of conversion were obtained, allowing for repetitive cycles. In addition, remarkably low levels of leaching of ru-

Unexpectedly high retention times were obtained in HPLC investigations for compounds equipped with (C 8 F 17 CH 2 CH 2 ) 3 Si tags on C 8 F 17 -modified silica gel (Fig. 4). Hence, these tags have a high potential for the noncovalent immobilization of catalysts to be applied in organic solvents, allowing for an easy separation and reuse of the catalyst by filtration and reapplication. The tris(perfluoroalkyl)silyl tag could be incorporated in a straightforward manner into ligands as demonstrated by the synthesis of several prominent classes of ligands (Schemes 4 ± 6).

A Grubbs–Hoveyda metathesis catalyst bearing a tris(perfluoroalkyl)silyl tag for efficient noncovalent attachment to fluorous silica gel (FSG) was synthesized and employed in ring‐closing metathesis (RCM) reactions in CH2Cl2. After the reaction, a solvent switch to a polar system allowed for recovery of the catalyst by filtration and its reuse. The approach was demonstrated for a number of different substrates. Furthermore, it was shown that the application of this catalytic system yielded products with low ruthenium content.