Ring-Closure Metathesis Using a Covalently Immobilized Grubbs Catalyst

Significance

The synthesis and application of novel solid-phase-bound Hoveyda-type catalysts and their successful application in RCM reactions in scCO₂ were described. Thus, the immobilized catalyst 4 was prepared in three steps starting from Hoveyda-type ligand 2 anchored on a novel hybrid silica gel. The reaction of carboxylic acid 2 with a new support material 1 gave the desired compound 3. Acylation of 3 to mask the unreacted amino residue followed by complexation with 5 in the presence of CuCl gave the solid-bound catalyst 4. The RCM reaction of N,N-diallyltosyl­amine was carried out in the presence of 5 in scCO₂ to give 2,5-dihydropyrrole in 93% yield. This catalyst was recovered and reused twice without significant loss of catalytic activity.