Silyl-Substituted Planar Chiral Phosphoric Acids with Ferrocene-bridged Paracyclophane Frameworks: Synthesis, Characterization, and Uses in Enantioselective aza-Friedel-Crafts Reactions

This manuscript reports on a suitable method for the synthesis of paracyclophane type, ferrocene-bridged chiral phosphoric acids, which bear silyl-substituents on their paracyclophane frameworks. These acids have been obtained easily in enantiomerically pure form, by taking advantage of (S)-(1-phenyl-2-cyanoethyl)phosphorodiamidite as a phosphorylating agent. They have been used then as catalysts for aza-Friedel-Crafts reactions between indoles and imines, giving high catalytic activity and up to 98% enantiomeric excess.