Ligand-Controlled Stereodivergent, Enantioselective Conjugate Addition of 2‑Oxazoline- and 2‑Thiazoline-4-carboxylate to Nitroalkene Catalyzed by Chiral Copper Complexes

The copper-catalyzed
asymmetric conjugate addition of 2-oxazoline-
and 2-thiazoline-4-carboxylate to a nitroalkene proceeded to give
either the syn or anti adduct selectively
in high enantiomeric excess when an appropriate chiral ligand was
used. Subsequent reduction of the nitro group followed by hydrolysis
of the oxazoline ring yielded an optically active γ-lactam of
protected α-quaternary serine derivative.