Planar Chiral Phosphoric Acids with Biphenylene-Tethered Paracyclophane Scaffolds: Synthesis, Characterization, and Catalytic Screening

Phosphoric acids with planar chiral paracyclophane scaffolds have been prepared in optically pure form starting from 1,8-dibromobiphenylene, by means of a chiral phosphorodiamidate as the phosphorylating agent Structural characterization and configurational assignment have been performed by X-ray diffraction studies. The acids promote the organocatalytic enantioselective H-transfer reduction of alpha-arylquinolines with up to 90% enantiomeric excess.