Transition-Metal-Catalyzed Asymmetric Synthesis of Bicyclo[3.3.1]nonane Frameworks

The bicyclo[3.3.1]nonane ring skeletons, with their distinctive three-dimensional structural features, are widely found in natural products, bioactive molecules, and functional materials, demonstrating significant value particularly in drug discovery. However, their structural rigidity and ring strain pose formidable synthetic challenges, including lengthy synthetic routes, poor selectivity, and low atom economy in conventional approaches. In recent years, transition-metal-catalyzed asymmetric synthesis has emerged as a powerful strategy for constructing bicyclo[3.3.1]nonane frameworks, owing to its efficiency and high selectivity. This review focuses on advances in Pd/Rh/Cu catalyzed asymmetric cyclization strategies for such architectures, systematically summarizing the characteristics and challenges of various reaction types, while providing perspectives on future research directions.