Synthesis and study of P-stereogenic BINAP analogs

ORGN 766

Eoin Micheal Rafter, eoin.rafter@ucd.ie, Declan Gilheany, declan.gilheany@ucd.ie, and Lee J Higham. School of chemistry and Chemical Biology, University College Dublin, Belfield, Dublin, 4, Ireland
Through the work of Noyori, BINAP has become one of the most successful ligands in asymmetric catalysis. Today a variety of analogues exist with modification both on the binaphthyl back-bone and on the ligands phenyl groups. We will present our recently developed synthetic route to BINAP analogues with chirality on one of the phosphorus atoms. The syntheses of these ligands were achieved by step-wise palladium and nickel-catalysed coupling reactions of the precursor binaphthyl triflate with secondary phosphines and phosphine oxides respectively. Separation of the product diastereomers required conversion of the phosphines to phosphine sulfides. Along with our P-chiral ligands we also synthesised C2-unsymmetric BINAP analogues with the same phenyl substituents. This series of ligands was tested in a variety of hydrogenation reactions to judge their applicability in asymmetric catalysis and to assess the difference in selectivity when a chiral phosphorus donor was present.