Synthesis and Characterization of New, Chiral P−N Ligands and Their Use in Asymmetric Allylic Alkylation

Several new ferrocenylimines containing both planar and central chirality were prepared from ( S p )-2-(diphenylphosphino)ferrocenecarboxaldehyde and chiral primary amines. One of these compounds, ( S p, S c )- 3, induced particularly high conversions (92−99%) and enantioselectivities (91−94% ee) when applied as a P−N ligand in the asymmetric allylic alkylation (AAA). In addition, a precatalyst complex was formed from ( S p, S c )- 3 and di-μ-chlorobis[(η 3 -C 3 H 5 )palladium(II)] and isolated after anion exchange with NaBF 4 to give [Pd(η 3 -C 3 H 5 )(( S p, S c )- 3 )]BF 4 ( 4 ). High conversions (99%) and enantioselectivities (90−93% ee) were also observed when the isolated precatalyst ( 4 ) was used in the AAA reaction. Crystal structures were obtained for all three ligands prepared for this study (( S p, S c )- 1 − 3 ) and for the isolated precatalyst ( 4 ). These compounds were also investigated by CD spectroscopy.