Nucleophilic addition to an achiral dehydroalanine Schiff base Ni(II) complex as a route to amino acids. A case of stereodetermining asymmetric protonation in the presence of TADDOL

We describe herein the elaboration of a new type of a substrate based on the Ni(II) complex of a Schiff base of dehydroalanine, 1, and Michael addition of nucleophiles to it, leading to the synthesis of racemic α-amino acids. We have also developed a catalytic method for the asymmetric 1,4 conjugate addition of achiral CH-acids to 1 promoted by TADDOLs with enantioselective catalytic protonation of the intermediate enolate in the stereodetermining stage of the reaction. A sizable 80% ee of the product was observed