Synthesis, Coordination Properties and Application of New N , N ‐Ligands Based on Bornyl and Binaphthylazepine Chiral Backbones in Palladium‐Catalyzed Allylic Substitution Reactions

The synthesis of new imine‐amine and diamine ligands, based on both the atropisomeric ( S a )‐ or ( R a )‐1,1′‐binaphthyl and ( R )‐bornyl backbones, and incorporating an ethylenediamino spacer, are reported. In addition, analogue ligands in which one chiral arm is replaced by the achiral NMe 2 group were synthesized. These N , N ‐ligands when coordinated to a palladium metal centre form highly enantioselective catalysts for the asymmetric allylic alkylation of rac ‐2‐acetoxy‐1,3‐diphenylpropene by dimethyl malonate. In one case, the synergic effect of the chirality elements in the palladium catalyst afforded the ( S ) substitution product with an enantiomeric excess ( ee ) of >99 %. Based on NMR studies of the active species in solution, a reliable explanation for the origin of the enantioselectivity of these palladium catalysts is also provided.