Synthesis of Medium-Sized\nRings by <i>Z</i>‑Retentive Asymmetric Allylic Substitution-Enabled\nIntermolecular\nCascade Cyclization under Iridium/Cinchona Catalysis

Medium-sized rings are important structural units in\norganic molecules\nof significant interest. However, their efficient synthesis, especially\nin a highly enantioselective manner, has been a formidable challenge.\nHerein, we report an enantioselective synthesis of medium-sized aza-rings\nby a <i>Z</i>-retentive asymmetric allylic substitution-enabled\nintermolecular cascade cyclization via iridium/cinchona dual catalysis.\nThe reaction was performed under mild conditions and with good functional\ngroup tolerance. Various nine- to eleven-membered aza-rings can be\nafforded in moderate to high yields (up to 98%) and enantioselectivities\n(up to 93% ee). The utilization of both <i>Z</i>-linear\nallylic dipole precursor and iridium/cinchona binary catalyst is critical\nfor the desired reactivity.