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

A one-pot reaction for the synthesis of 1-pyrrolines from allylic azides and diazomalonates has been designed and developed. This conversion involves a sequential two-step process of interception of a diazomalonate by the allylic azide and base-mediated cyclization of the resultant N-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.