Journal of the American Chemical Society, Vol.143, No.3, 1328-1333, 2021
Synthesis of Axially Chiral 2,2 '-Bisphosphobiarenes via a Nickel-Catalyzed Asymmetric Ullmann Coupling: General Access to Privileged Chiral Ligands without Optical Resolution
We report an asymmetric homocoupling of ortho-(iodo)arylphosphine oxides and ortho-(iodo)arylphosphonates resulting in highly enantioenriched axially chiral bisphosphine oxides and bisphosphonates. These products are readily converted to enantioenriched biaryl bisphosphines without need for chiral auxiliaries or optical resolution. This provides a practical route for the development of previously uninvestigated atroposelective biaryl bisphosphine ligands. The conditions have also proven effective for asymmetric dimerization of other, non-phosphorus-containing aryl halides.