Convenient, Large-Scale Asymmetric Synthesis of Enantiomerically Pure trans-Cinnamylglycine and -α-Alanine

Asymmetric syntheses of (S)-trans-cinnamylglycine and (S)-α-trans-cinnamyl-α-alanine via reactions of cinnamyl halides (Cl, Br) with Ni(II)-complexes of the chiral Schiff base of glycine or alanine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone were developed. Inexpensive and readily available reagents and solvents were used, including an easily recyclable chiral auxiliary. The simplicity of the experimental procedures and the high stereochemical outcome make this method synthetically attractive for preparing the target amino acids on multi-gram scales.