The synthesis of silica-and monolithsupported Grubbs±Herrmann-type catalysts is described. Two polymerizable, carboxylate-containing ligands, exo, exo-7-oxanorborn-2-ene-5,6-dicarboxylic anhydride and 7-oxanorborn-2-ene-5-carboxylic acid were surface-immobilized onto silica-and ring-opening metathesis (ROMP-) derived monolithic supports using ™grafting-from∫ techniques. The ™1 st generation Grubbs catalyst∫, RuCl 2 ( CHPh)(PCy 3 ) 2 , was used for these purposes. In addition, a poly(norborn-2-eneb-exo, exo-norborn-2-ene-5,6-dicarboxylic anhydride) -coated silica 60 was prepared. The polymer supported anhydride and carboxylate groups were converted into the corresponding mono-and disilver salts, respectively, and reacted with the Grubbs±Herrmann catalyst RuCl 2 ( CHPh)(IMesH 2 )(PCy 3 ) [IMesH 2 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene]. Heterogenization was accomplished by exchange of one chlorine ligand with the polymeric, immobilized silver carboxylates to yield monolithsupported catalysts 4, 5, and 6 as well as silicasupported systems 7, 8 and 9. The actual composition of these heterogenized catalysts was proven by the synthesis of a homogeneous analogue, RuCl[7-oxanorbornan-2-(COOAg)-3-COO]( CHPh)(IMesH 2 )(PCy 3 ) (3). All homogeneous and heterogeneous catalysts were used in ring-closing metathesis (RCM) of diethyl diallylmalonate, 1,7-octadiene, diallyldiphenylsilane, methyl trans-3-pentenoate, diallyl ether, N,N-diallyltrifluoracetamide and t-butyl N,N-diallylcarbamate allowing turnover numbers (TON×s) close to 1000. In a flow-through set-up, an auxiliary effect of pendant silver carboxylates was observed with catalyst 5, where the silver moiety functions as a (reversible) phosphine scavenger that both accelerates initiation and stabilizes the catalyst by preventing phosphine elution. Detailed catalytic studies were carried out with the monolith-supported systems 4 and 6 in order to investigate the effects of temperature and chain-transfer agents (CTA×s) such as cis-1,4-diacetoxybut-2-ene. In all RCM experiments Ruleaching was low, resulting in a Ru-content of the RCM products 3.5 mg/g (3.5 ppm).
