engleski

"Backdoor induction" of chirality: Trans‐1, 2‐cyclohexanediamine as key building block for asymmetric hydrogenation catalysts

This paper describes the synthesis and characterization of 21 chiral monodentate ligands L, assembled of three building blocks utilizing amide bonds: a metal binding triphenylphosphine, a chiral cyclic diamine and an additional substituent for fine-tuning the steric and/or electronic properties. Cis square-planar metal complexes of Rh(I) and Pt(II) with ML2 stoichiometry have been prepared and characterized by spectroscopic methods (NMR, IR, UV-Vis, CD) and DFT calculations. Key feature of the metal complexes is a prochiral metal coordination sphere and "backdoor induction" of chirality from a distant chiral source via an outer-coordination sphere, welldefined by aromatic stacking and hydrogen-bonding. The rhodium complexes were used as catalysts in asymmetric hydrogenation of α, β-dehydroamino acids with excellent yield and selectivity (up to 97% ee), strongly supporting the "backdoor induction" hypothesis.

Enantioselective catalysis ; backdoor induction ; hydrogenation ; supramolecular ; chirality transfer

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