Hoveyda–Grubbs first generation type catalyst immobilized on mesoporous molecular sieves

• Hoveyda–Grubbs type catalyst was immobilized on mesoporous molecular sieves.
• The immobilization performed via exchange of phosphine ligands.
• Reusable catalysts of low Ru leaching were prepared.
• Activity of catalysts in RCM increased with increasing pore size of supports.

New heterogeneous, reusable catalysts for olefin metathesis have been prepared by immobilizing the Hoveyda–Grubbs first generation type alkylidene (commercially available as the Zhan catalyst-1C) on siliceous mesoporous molecular sieves with different pore sizes and architectures (SBA-15, SBA-16, MCM-41 and MCM-48) having the surface modified with molecules bearing dicyclohexylphosphine (PCy2) end groups. Resulting novel heterogenized catalysts proved high activity in ring-closing metathesis (RCM) of 1,7-octadiene, diethyl diallylmalonate, tert-butyl N,N-diallylcarbamate and N,N-diallyl-2,2,2-trifluoroacetamide, in homometathesis of 1-decene, 5-hexenyl acetate and methyl 10-undecenoate, and in cross-metathesis (CM) of allylbenzene with cis-1,4-diacetoxy-2-butene. The catalytic activity decreased with decreasing pore size of supports in the order SBA-15 > MCM-48 > SBA-16 and MCM-41. Filtration test suggested that the solid catalyst was responsible for the catalytic activity. Catalysts were easily separated from the reaction mixtures and products of low levels of Ru concentration were obtained.

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