Asymmetric catalytic hydroformylation of styrene: Stereoselective ferrocenylethyldiphosphine rhodium catalysts

The use of a variety of chiral ferrocenylethyl diphosphines and a rhodium(I) precursor for the asymmetric hydroformylation of styrene is described. Some of these catalysts yield the chiral 2-phenylpropionic aldehyde with high enantioselectivity. The selectivity and activity of the catalysts are influenced by the substitution pattern of the phosphines. High enantioselectivity was achieved even at high reaction temperatures with a dialkylaryl-alkyldiaryl diphosphine ligand. o-Anisyl substituents at the side-chain phosphorus yield optical inductions of up to 76% ee, but at low conversion rates.