Copper-Catalyzed Nucleophilic Cycloisomerization Cascade Constructing Azepinoindolizine

Numerous effective bioisosteric replacements have been identified through substituting scaffolds and functional groups in lead molecules with alternative ones that preserve or enhance the desired biological activity of the original compound. Here, a copper-catalyzed nucleophilic cycloisomerization was developed to access potential bioisosteric replacements of azepinoindole. In this process, "tetra-alkene" characteristic of indolizine undergoes a 12π electrocyclization, offering a complementary method to obtain azepinoindolizine derivatives that are otherwise challenging to prepare through conventional means.