Beschreibung:
<jats:title>Abstract</jats:title><jats:p>A very efficient synthesis of 2,3‐diaryl‐β‐amino acid derivatives is realized by a TiCl<jats:sub>4</jats:sub>/triethylamine‐catalyzed Mannich‐like reaction of arylacetic or arylthioacetic esters with arylimines. The presence on the arylacetic moiety of an <jats:italic>ortho</jats:italic>‐heteroatom group able to coordinate to the titanium center is of dramatic importance for the outcome of the reaction and to tune the <jats:italic>syn</jats:italic>/<jats:italic>anti</jats:italic> diastereoselection. In particular, with <jats:italic>o</jats:italic>‐F‐, <jats:italic>o</jats:italic>‐Cl‐, and <jats:italic>o</jats:italic>‐Br‐arylacetates, the <jats:italic>syn</jats:italic> adduct was isolated as the largely prevalent isomer. When (–)‐8‐phenylmenthyl (2‐fluorophenyl)acetate was used, the condensation with imines resulted in high diastereo‐ and enantioselectivity. In agreement with the stereochemical results and NMR studies, a conceivable reaction mechanism was proposed.</jats:p>