TOWARDS NEW FERROCENYL LIGANDS FOR ASYMMETRIC CATALYSIS

Some new approaches for asymmetric synthesis of chiral ferrocenyl liga nds are described. Many types of ferrocene compounds with planar chira lity were prepared through diastereoselective ortholithiation, thanks to a chiral sulfoxide or chiral acetal auxiliary. Various mono- and di phosphines may be subsequently generated. In the sulfoxide route, a ke y intermediate is pure monolithioferrocene. A convenient procedure was set up, involving the isolation of stable tri-n-butylstannyl-ferrocen e as a precursor of monolithioferrocene. The species Fc(2)PH (Fc = fer rocenyl) and its borane protected derivative allowed to synthesize chi ral diphosphines where the usual PPh(2) groups are replaced by the PFc (2) fragment.