One-Pot Synthesis of 1‑Pyrrolines via Rh₂(esp)₂‑Catalyzed Intermolecular Reaction of Allylic Azides with Diazomalonates Followed by DBU-Mediated Allylic Imine Cyclization

This conversion involves a sequential two-step process of interception of a diazomalonate by the allylic azide and base-mediated cyclization of the resultant <i>N</i>-allyl imine intermediate. Rh₂(esp)₂ was identified as the optimized catalyst for the initial carbenoid interception step, while DBU proved to be an effective promoter for the cyclization step, efficiently affording 30 diverse 1-pyrrolines in up to 91% yield under very mild conditions.