X-Ray characterization of enantiomerically pure 1,1′-diphenyl-3,3′,4,4′-tetramethyl-2,2′-biphosphole: a ligand with axial and central chirality

Chiral [(Dialkylamino)methyl](phospholyl)ferrocene Ligands as a New Class of 1,2‐Disubstituted Ferrocene Ligands

“…1 H, 13 Acetal 1 [14] and 1-cyano-3,4-dimethylphosphole (2) [15] were prepared as described in the literature.…”

“…This compound, which is slightly unstable, was only characterised by 1 H and 31 P NMR spectroscopy and then reduced with sodium tetrahydroborate to the stable alcohol (S)-5. This compound, obtained in 90% yield by column chromatography, was fully characterized by 1 H, 13 C and 31 P NMR spectroscopy and the (S)-configuration was confirmed by an X-ray diffraction analysis. A molecular view of the alcohol (S)-5 is shown in Figure 1, with the atom-labelling Scheme 1.…”

“…So, as part of our continuing interest in ferrocene chemistry [12] and in the design and synthesis of new chiral phosphole-based ligands, [13] we decided to investigate the efficiency of mixed phospholylferrocene ligands in asymmetric catalysis. Herein, we report the synthesis and characterization of the [(dialkylamino)methyl](phospholyl)-…”

New Rhodium(I) and Iridium(I) Complexes of the Chiral 1,1′-Diphenyl-3,3′,4,4′-tetramethyl-2,2′-biphosphole Ligand − Synthesis and Applications to Catalytic Hydrogenation and Hydroformylation Reactions

“…This implies the existence of six stereoisomers corresponding to three pairs of enantiomers (Figure 1). In a previous report, [4] we have shown that BIPHOS exists in solution as an equilibrium mixture of two diastereoisomers, 1a and 1b, because of the configurational instability of the central chirality of the phosphorus atoms and probably also because of the axial chirality. This stereolability does not exist in the solid state and the three diastereoisomers have been fully characterized by X-ray diffraction.…”

“…This stereolability does not exist in the solid state and the three diastereoisomers have been fully characterized by X-ray diffraction. [4] In solution in the presence of a transition metal, the equilibrium shifts to the most favorable configurations for chelating the metal {[a] S RR and [a] R SS }. In this way, we have obtained numerous chiral complexes of Ni, Pd, Pt, Rh [5] and Ru, [6] as racemic mixtures.…”