Pd(0) and Pd(II) derivatives with heteroannularly bridged chiral ferrocenyl diphosphine ligands – A stereochemical analysis

The ligands (Sc, Sp)-1-diphenylphosphino-2,1′-(1-dicyclohexylphosphinopropanediyl)ferrocene, (Sc, Sp)-PPCyPF, and (Sc, Sp)-1-diphenylphosphino-2,1′-(1-diphenylphosphinopropanediyl)ferrocene, (Sc, Sp)-PPPhPF, have been used in the synthesis of the new Pd(0) and Pd(II) derivatives [Pd(PPCyPF)(DMFU)] (1) (DMFU = dimethylfumarate), [Pd(PPCyPF)(MA)] (2) (MA = maleic anhydride), [Pd(η3-2-Me-C3H4)(PP)]OTf (PP = PPCyPF, 3; PPPhPF, 4) (OTf = triflate), [PdRR′(PP)] (R = Me, R′ = Cl, PP = PPCyPF, 5, PPPhPF, 6; R = R′ = Me, PP = PPCyPF, 7, PPPhPF, 8; R = R′ = C6F5, PP = PPCyPF, 9, PPPhPF, 10). The molecular structure of 7 has been determined by X-ray diffraction. In the cases of complexes 1–4 two isomers are formed depending on the orientation of the ancillary ligand with respect to the ferrocenyl core. The stereochemistry of these complexes has been determined. In complex 6 the two possible isomers are obtained whereas in complex 5 the derivative with the Me group trans to PPh2 is selectively formed. Restricted rotation of the pentafluorophenyl groups with respect to the Pd–C bond has been found in 9 and 10. In all derivatives the conformation of the ferrocenyl ligand is the same as that seen by X-ray diffraction and deduced from NMR data.

New Pd(0) and Pd(II) complexes have been obtained using chiral ferrocenyl diphosphine ligands. For the olefin, allyl or chloromethyl derivatives the presence of isomers and their stereochemistry has been studied. The conformation of the rigid ligands is the same in solution and in the solid state (X-ray diffraction study).Figure optionsDownload as PowerPoint slide