β-Ketoester dianions as regiospecific enolate equivalents for N-substituted pyrrolidin-3-ones

Double deprotonation of β-ketoester (6) gives dianion (7) which serves as a synthetic equivalent of the regiospecific ketone enolate (3), providing a synthetic entry to 2-substituted pyrrolidin-3-ones (9) and (10).