Copper-Catalyzed Aerobic Oxidative Cyclization Cascade to Construct Bridged Skeletons: Total Synthesis of (-)-Suaveoline

Based on the discovery of copper-catalyzed cyclopropanol ring-opening addition to iminium ions, an unprecedented catalytic aerobic C-H oxidation/cyclopropanol cyclization cascade using CuCl2 as the multifunctional catalyst and air as the oxidant was developed to construct the azabicyclo[3.3.1]nonane skeleton, which is widespread in natural products and medicines. Using this method, concise asymmetric total synthesis of the indole alkaloid (-)-suaveoline was achieved. This study not only provides an efficient, low-cost, and environmentally benign method for constructing such bridged frameworks, but also enriches the realm of cyclopropanol chemistry and C-H functionalization.