CHIRAL DISCRIMINATION IN ORGANOMETALLIC SYSTEMS. REACTION BETWEEN + AND (S,S)(-)589-o-PHENYLENEBIS(1,2-METHYLPHENYLPHOSPHINE)

Article abstract of DOI:10.1016/S0022-328X(00)86856-4

Attack on the dienyl ring of racemic (I) by (S,S)(-)₅₈₉-o-phenylenebis(1,2-methylphenylphosphine) (II) exhibits considerable kinetic diastereoselectivity in acetonitrile and acetone solvents.The corresponding reaction in dichloromethane is of lower selectivity.Recovery of unreacted dienyl salt from reactions between I and II (1/0.5 molar ratio) provides a convenient method for preparing optically active I.The CD spectrum of the latter complex is reported for the first time.Unexpectedly, the 50/50 mixture of diastereomers obtained immediately upon reacting (R,S)-I and II in a 1/1 molar ratio, equilibrates over three days in acetonitrile to a 60/40 mixture.Thermodynamic chiral discrimination thus also operates in these systems, and the mechanism of this unexpectedly rapid inversion at the chiral iron centre is under investigation.