The application of “backdoor induction” in bioinspired asymmetric catalysis

Abstract

Amino acid substituted monodentate triphenylphosphine ligands Lig-Aa₁-Aa₂-Aa₃-Z 5 and 6, with a C-terminal ester or amide group, respectively, were prepared in a few simple synthetic steps. Supramolecular in situ formed complexes [Rh(COD)(Lig-Aa₁-Aa₂-Aa₃-Z)₂]BF₄3 and 4 with a prochiral coordination sphere of the metal are selective hydrogenation catalysts (up to 68% ee). The selectivity is induced by transmission of chirality via distant hydrogen-bonded amino acids with a Herrick-like secondary structure (“backdoor induction”).