Enantioselective synthesis of anti-β-substituted γ,δ-unsaturated amino acids:: A highly selective asymmetric thio-claisen rearrangement

A novel synthesis of optically active anti-beta-substituted gamma,delta-unsaturated amino acids via a thio-Claisen rearrangement has been achieved. A 2,5-diphenylpyrrolidine was used as a C-2-symmetric chiral auxiliary to control the stereochemistry, giving good yields and excellent diastereoselectivities and enantioselectivities.