Rational Design of Chiral 1,1’-Binaphthylazepine-based Ligands for the Enantioselective Addition of ZnEt2 to Aromatic Aldehydes

By rational design, novel atropisomeric 1,1-binaphthylazepine-based 1,2-amino alcohols 1f and 1g have been prepared in enantiopure form and tested as catalytic precursors in the enantioselective addition of diethylzinc to aromatic aldehydes: the corresponding (S)-1-arylpropanols have been obtained in quantitative yields and e.e.s up to 95%. A rationale explaining the stereochemical outcome of the reaction, as well as the influence of structural features of the ligands on the enantioselectivity of the addition, is also provided