Design and Synthesis of a New Generation of ‘NH’-Ni(II) Complexes of Glycine Schiff Bases and their Unprecedented C-H vs. N-H Chemoselectivity in Alkyl Halide Alkylations and Michael Addition Reactions

Within this manuscript the synthesis of a new generation of Ni(II) complexes that contain a secondary rather than a tertiary amino group, as well as the unusual chemoselectivity, was demonstrated in alkyl halide alkylations and Michael addition reactions. The complete C-H chemoselectivity observed in these reactions suggests that coordination of nitrogen to a metal has a significant synthetic potential as protecting a group without the need of introducing a transient N-C substituent. These new complexes have also proven highly synthetically useful nucleophilic glycine equivalents for the simple and highly diastereoselective synthesis of (beta)-sub­stituted pyroglutamic acids via their reactions with chiral Michael acceptors.