Resolution of the Atropochiral Biminap Ligand and Applications in Asymmetric Catalysis

Abstract

Enantiomeric resolution of the rac‐biminap ligand is achieved through fractional crystallization of four diastereoisomeric palladium complexes involving ortho‐metallated enantiomerically pure (R)‐dimethyl(1‐naphthylethyl)amine as a chiral auxiliary. After decomplexation, the absolute configuration of (R)‐biminap and (S)‐biminap has been unambiguously attributed by single‐crystal X‐ray crystallography, and their stereochemical purity is confirmed by measurement of their optical rotation and by re‐derivatization with the initial resolving chiral complex. Palladium complexes of biminap are shown to efficiently catalyze Tsuji–Trost allylic substitution of 3‐acetoxy‐1,3‐diphenylpropene by sodium dimethyl malonate. In the asymmetric version using the enantiomerically pure (R)‐biminap ligand, significant solvent and anion effects are evident, and an ee up to 90 % is obtained.