Planar chiral phosphoric acids with biphenylene-tethered paracyclophane scaffolds: synthesis, characterization, and catalytic screening

J Org Chem. 2014 Oct 17;79(20):9639-46. doi: 10.1021/jo501769t. Epub 2014 Oct 6.

Abstract

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 α-arylquinolines with up to 90% enantiomeric excess.