Chiral Pyridoxamines Featuring Proton-Donating Auxiliary Side Chains for Asymmetric Biomimetic Transamination

Inspired by transaminases, we developed a novel class of chiral pyridoxamine featuring an auxiliary proton-donating side chain. These catalysts exhibited excellent activity and enantioselectivity in the asymmetric transamination of α-keto acids, affording various chiral α-amino acids in up to 97% yield with 93% ee. The strategic introduction of the auxiliary proton-donating side chain likely promotes the protonation of delocalized azaallylanion in the 1,3-proton transfer, leading to improvement in both catalytic activity and enantioselectivity.