Efficient Total Synthesis of Densely Functionalized Natural Products by New Complexity-Generating Strategy

We have conducted synthetic studies of densely functionalized natural products. To complete total syntheses of these natural products in an efficient manner, we developed some new complexity-generating strategies. This review describes 2 novel synthetic routes to batrachotoxin, a steroidal alkaloid with potent neurotoxicity and puberuline C, a hexacyclic C19-diterpenoid alkaloid. In batrachotoxin synthesis, the intermolecular coupling of AB-ring and D-ring fragments was realized at sterically congested positions by utilizing a palladium/silver (Pd/Ag)-promoted Suzuki–Miyaura coupling reaction. In the synthesis of puberuline C, the 2 rings and 5 contiguous stereocenters were simultaneously constructed by a radical cascade reaction, increasing the complexity of the molecule in a single step.