Post‐Ugi Cyclizations Towards Polycyclic N‐Heterocycles

AbstractThe Ugi reaction has become one of the highly explored reactions for the formation of multifunctional adducts, due to the mild reaction conditions, wide scope and high variability. By carefully selecting the starting four components, Ugi‐adducts could undergo different kinds of post‐transformations for the synthesis of bioactive heterocycles, natural products and macrocycles. Considering the significance of polycycles, diverse post‐Ugi transformations have been developed over the years for constructing structurally novel polycycles. In this account, we summarize important efforts for the synthesis of polycyclic N‐heterocycles via post‐Ugi cyclizations from the Van der Eycken laboratory onwards 2016. With the aid of transition metal catalysis from gold, rhodium, silver and palladium, as well as metal‐free strategies, versatile polyheterocycles are prepared with high efficiency and step‐economy.