Synthesis of Bicyclo[2.2.1]Heptanes via Pyridine-Boronyl Radical-Catalyzed [2π + 2σ] Cycloaddition

Bicyclo[2.2.1]heptanes (BCHeps) are essential polycyclic compounds in many natural products and pharmaceutical molecules. Efficient synthetic strategies for BCHeps and their derivatives are desirable and challenging. In this work, bicyclo[2.1.0]pentanes (BCPs) have been strategically employed as building blocks for the development of a [2π + 2σ] cycloaddition reaction with alkenes. The key to success is using a pyridine-assisted boronyl radical catalysis approach. This provides a modular and atom-economical method, using simple and inexpensive catalysts, for efficient synthesis of BCHeps. The substrate scope has been explored. A possible reaction mechanism has been proposed, and the synthetic utility has been demonstrated by downstream transformations.