Versatile Ru-based metathesis catalysts designed for both homogeneous and heterogeneous processes |
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Affiliation: | 1. Institute of Biochemistry, Nutrition and Health Protection, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic;2. Institute of Management of the Slovak University of Technology in Bratislava, Vazovova 5, SK-812 43 Bratislava, Slovak Republic;3. Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic |
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Abstract: | The synthesis of new ruthenium-based catalysts applicable for both homogeneous and heterogeneous metathesis is described. Starting from the Hoveyda-Grubbs first generation (1) and the Hoveyda-Grubbs second generation (2) catalysts the homogeneous catalysts [RuCl((RO)3Si–C3H6–N(R′)–CO–C3F6–COO)(CH–o-O–iPr–C6H4)(SIMes)] (4: R = Et, R′ = H; 5: R = R′ = Me) (SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) were prepared by substitution of one chloride ligand with trialkoxysilyl functionalized silver carboxylates (RO)3Si–C3H6–N(R′)–CO–C3F6–COOAg (3a: R = Et, R′ = H; 3b: R = R′ = Me). These homogeneous ruthenium-species are among a few known examples with mixed anionic ligands. Exchange of both chloride ligands afforded the catalysts [Ru((RO)3Si–C3H6–N(R′)–CO–C3F6–COO)(CH–o-O–iPr–C6H4)(SIMes)] (9: R = Et, R′ = H; 11: R = R′ = Me) and [Ru((RO)3Si–C3H6–N(R′)–CO–C3F6–COO)(CH–o-O–iPr–C6H4)(PCy3)] (8: R = Et, R′ = H; 10: R = R′ = Me). The reactivity of the new complexes was tested in homogeneous ring-closing metathesis (RCM) of N,N-diallyl-p-toluenesulfonamide and TONs of up to 5000 were achieved. Heterogeneous catalysts were obtained by reaction of 4, 5 and 8–11 with silica gel (SG-60). The resultant supported catalysts 4a, 5a, 8a–11a showed reduced activity compared to their homogenous analogues, but rival the activity of similar heterogeneous systems. |
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