P-Chirogenic Phosphine Ligands

Cr6py KVL, Imamoto T (2003) New P-Chirogenic Phosphine Ligands and Their Use in Catalytic Asymmetric Reactions. 229 1-40 Cristau H-J, see Taillefer M (2003) 229 41-73... 

New P-Chirogenic Phosphine Ligands and their Use in Catalytic Asymmetric Reactions... 

Brief Historical Overview of P-Chirogenic Phosphine Ligands... 

Scheme 1. First use of P-chirogenic phosphine ligands in asymmetric hydrogenation reaction...

Thereafter, however, P-chirogenic phosphine ligands were the subject of less investigation since the synthesis of highly enantiomerically enriched P-stereo-genic phosphines often proves difficult. Another reluctance Hes in the fact that this class of phosphines, especially diaryl- and triarylphosphines, is conforma-tionally unstable and gradually racemize at high temperature [57,58]. In contrast, optically active trialkylphosphines are known to be optically stable even at considerably elevated temperature. 

Scheme 20. Example of synthesis of a ferrocenyl-based P-chirogenic phosphine ligand...

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