Rapid synthesis of substituted pyrrolines and pyrrolidines by nucleophilic ring closure at activated oximes

Substituted pyrrolines are available by ring closure initiated by direct nucleophilic attack of stabilized enolates at the nitrogen of oximes activated with a leaving group, in a process which effectively out-competes the more usual Beckmann rearrangement. Subsequent reduction provides diastereoselective access to the corresponding pyrrolidines. This provides a rapid route to saturated heterocyclic systems from readily available precursors.