Asymmetric synthesis of novel ferrocenyl ligands with planar and central chirality and their application to Pd-catalyzed allylic substitutions

An efficient and flexible asymmetric synthesis of planar chiral ferrocenyl ligands bearing a stereogenic centre at the beta -position to the metallocene backbone is described. A variety of donor groups can be independently introduced as electrophiles, thus allowing electronic and steric fine-tuning of the ligands, which were investigated in Pd-catalyzed enantioselective allylic substitutions. By employing a P,S ligand, the alkylation of the standard test system (+/-)-1,3-diphenyl-2-propenyl acetate using dimethyl malonate/BSA as the nucleoph- ile proceeded in a quantitative yield with an ee of 97%, which is the best value reported so far in this reaction for a P boolean ORS ligand.