EnantioselectiveSynthesis of 2‑Azanorbornanes:Chiral Trisimidazoline-Catalyzed Desymmetrizing Transannular Bromoaminocyclization

An enantioselective desymmetrizing transannular bromoaminocyclization of cyclopentenylamines has been achieved by using <i>C</i>₃-symmetric trisimidazoline catalysis. This protocol could directly provide a range of chiral 2-azanorbornanes in excellent yields (up to 99%) and enantioselectivities (up to 97.5:2.5 enantiomeric ratio). The resulting enantioenriched 2-azanorbornanes are easily converted to synthetically useful building blocks. Further mechanistic investigations show that the presence of three imidazoline groups of the catalyst is crucial to the success of the enantioselective transformation.