Straightforward regio- and stereo-selective synthesis of t-2-[(diphenylphosphinoyl)methyl]-c-3-(disubstitutedphosphinoyl)-r-1-cyclopentanols

Palladium-Catalyzed Regio- and Enantioselective Hydrophosphination of gem-Difluoroallenes

Chiral allylic phosphines and gem-difluoroalkenes are both important structural motifs in various bioactive molecules, chiral ligands, and natural products. These two motifs are now integrated, and we herein report a straightforward and atom-economical enantioselective hydrophosphination of gem-difluoroallenes using disubstituted phosphines. A wide array of enantioenriched fluorinated allylic phosphines has been accessed with excellent regio- and enantioselectivity and high efficiency. Synthetic and catalytic applications of phosphine products have been demonstrated.

Nickel/Brønsted acid dual-catalyzed regio- and enantioselective hydrophosphinylation of 1,3-dienes: access to chiral allylic phosphine oxides

While chiral allylic organophosphorus compounds are widely utilized in asymmetric catalysis and for accessing bioactive molecules, their synthetic methods are still very limited. We report the development of asymmetric nickel/Brønsted acid dual-catalyzed hydrophosphinylation of 1,3-dienes with phosphine oxides. This reaction is characterized by an inexpensive chiral catalyst, broad substrate scope, and high regio- and enantioselectivity. This study allows the construction of chiral allylic phosphine oxides in a highly economic and efficient manner. Preliminary mechanistic investigations suggest that the 1,3-diene insertion into the chiral Ni-H species is a highly regioselective process and the formation of the chiral C-P bond is an irreversible step.

Theoretical Study of the Structures of 4-(2,3,5,6-Tetrafluoropyridyl)Diphenylphosphine Oxide and Tris(Pentafluorophenyl)Phosphine Oxide: Why Does the Crystal Structure of (Tetrafluoropyridyl)Diphenylphosphine Oxide Have Two Different P=O Bond Lengths?

The crystal structure of 4-(2,3,5,6-tetrafluoropyridyl)diphenylphosphine oxide (1) contains two independent molecules in the asymmetric unit. Although the molecules are virtually identical in all other aspects, the P=O bond distances differ by ca. 0.02 Å. In contrast, although tris(pentafluorophenyl)phosphine oxide (2) has a similar crystal structure, the P=O bond distances of the two independent molecules are identical. To investigate the reason for the difference, a density functional theory study was undertaken. Both structures comprise chains of molecules. The attraction between molecules of 1, which comprises lone pair-π, weak hydrogen bonding and C-H∙∙∙arene interactions, has energies of 70 and 71 kJ mol^-1. The attraction between molecules of 2 comprises two lone pair-π interactions, and has energies of 99 and 100 kJ mol^-1. There is weak hydrogen bonding between molecules of adjacent chains involving the oxygen atom of 1. For one molecule, this interaction is with a symmetry independent molecule, whereas for the other, it also occurs with a symmetry related molecule. This provides a reason for the difference in P=O distance. This interaction is not possible for 2, and so there is no difference between the P=O distances of 2.