TOWARDS NEW FERROCENYL LIGANDS FOR ASYMMETRIC CATALYSIS

Some new approaches for asymmetric synthesis of chiral femenyl ligands are described. Many types of ferrocene compounds with planar chirality were prepared through diastereoselective ortholithiation, thanks to a chiral sulfoxide or chiral aced auxiliary. Various mono- and diphosphines may be subsequently generated. In the sulfoxide route, a key intermediate is pure monolithioferrocene. A convenient procedure was set up, involving the isolation of stable tri-n-butylstannyl-femene as a precursor of monolithioferrocene. The species FczPH (Fc = ferrocenyl) and its borane protected derivative allowed to synthesize chiral diphosphines where the usual PPh2 groups are replaced by the PFc2 fragment.