Constraining asymmetric organometallic catalysts within mesoporous supports boosts their enantioselectivity

Raja, Robert, Thomas, John Meurig, Jones, Matthew D., Johnson, Brian F.G. and Vaughan, David E.W. (2003) Constraining asymmetric organometallic catalysts within mesoporous supports boosts their enantioselectivity. Journal of the American Chemical Society, 125 (49), 14982-14983. (doi:10.1021/ja030381r).

Abstract

By constraining tethered asymmetric organometallic catalysts within the nanopores of silica supports so as to increase the interaction between the pore wall and the active center (and hence to restrict access of the reactant to the catalyst) a significant improvement in enantioselectivity is achieved. A schematic illustration of a cationic chiral, organometallic catalyst, [Rh(I)(COD)PMP] {(S)-(+)-1-(2-pyrrolidinylmethyl)-pyrrolidine and cyclooctadiene}, which is non-covalently anchored, via a N–H••••F hydrogen bond with the triflate ion, CF3SO3-, to the curved inner surface of a 38 Å diameter pore of a silica support, for the asymmetric hydrogenation of the C=O bond in methyl benzoylformate to the corresponding methyl mandelate is shown. Rh (purple); N (blue); H (white); F (green); C (grey); S (yellow); O (red).

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Contributors

Author: Robert Raja

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