Enantiomerically Pure P,N Chelates Based on Phospholene Rings: Palladium Complexes and Catalytic Applications in Allylic Substitution

The synthesis of optically pure 2pyridylphospholene ligands by diastereomeric resolution of PdIIcomplexes, bearing the corresponding racemic P,N ligand and Rαmethylbenzylamine, by means of fractional crystallisation is described. A full coordination study of palladium complexes containing 2pyridylphospholene and the corresponding phosphole ligands, both in solution by means of NMR spectroscopy and in the solid state by Xray diffraction, was carried out. These ligands were evaluated in Pdcatalysed allylic substitution of racemic substrates rac3acetoxy1,3diphenyl1propene and rac3acetoxy1cyclohexene and E3acetoxy1phenyl1propene. A modelling study of the palladium allylic intermediates was performed in order to justify the asymmetric induction observed with the 2pyridylphospholene ligands.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009