Development of a New ‘Axially Chiral’ Bisphosphine Ligand

Significance

The authors describe the synthesis of a new axially chiral bisphosphine ligand, which is shown to be extremely effective for the isomerization of racemic α-arylpropargyl alcohols to yield β-chiral indanones. The newly designed ligand outperformed all of the ‘standard’ bisphosphine ligands, including BINAP, MeO-biphep, segphos and H₈-BINAP. The authors subjected enantioenriched α-arylpropargyl alcohols to the reaction conditions and found that only the S-enantiomer reacted! They concluded that the initial formation of the ketone is the subject of kinetic resolution.