engleski

"Backdoor induction" of chirality in asymmetric hydrogenation with rhodium(I) complexes of amino acid substituted triphenylphosphane ligands"

This paper describes the synthesis and characterization of 5-(di-phenylphosphino)isophthalic acid bioconjugates, Lig-[R]2. In addition to symmetrically disubstituted conjugates with amino acids (1a-1e and 4f-4g), peptides (2a-2e and 3a-3b) or amines (4a-4e), a convenient one pot two step procedure for the synthesis of conjugates 5a-g bearing two different substituents is reported. The 28 prepared phosphanes 1-5 are used as monodentate ligands in the rhodium(I) catalyzed hydrogenation of 2-acetamidoacrylate or (Z)-(alpha)-acetamidocinnamate. Ligand with small side chain substituents Lig-[Ala-OMe]2 1a revealed highest selectivity with up to 84 % ee. The catalysts presented herein are models of artificial metalloenzymes where the secondary coordination sphere controls the selectivity in catalysis. The chirality of distant hydrogen-bonded amino acids is transmitted by "backdoor induction" to the prochiral Rh(I).

amino acids; artificial metalloenzymes; asymmetric catalysis; metallated bioconjugates; supramolecular chemistry

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