Synthesis of Medium-Sized Rings by Z-Retentive Asymmetric Allylic Substitution-Enabled Intermolecular Cascade Cyclization under Iridium/Cinchona Catalysis

Medium-sized rings are important structural units in organic molecules of significant interest. However, their efficient synthesis, especially in a highly enantioselective manner, has been a formidable challenge. Herein, we report an enantioselective synthesis of medium-sized aza-rings by a Z-retentive asymmetric allylic substitution-enabled intermolecular cascade cyclization via iridium/cinchona dual catalysis. The reaction was performed under mild conditions and with good functional group tolerance. Various nine- to eleven-membered aza-rings can be afforded in moderate to high yields (up to 98%) and enantioselectivities (up to 93% ee). The utilization of both Z-linear allylic dipole precursor and iridium/cinchona binary catalyst is critical for the desired reactivity.