Chemoselective Silver-Catalyzed Nitrene Transfer: Tunable Syntheses of Azepines and Cyclic Carbamimidates

Azepines and their saturated azepane counterparts are important moieties in bioactive molecules but are under-represented in current drug screening libraries. Herein, we report a mild and efficient azepine formation via silver-catalyzed dearomative nitrene transfer. A 2,2,2-trichloroethoxysulfonyl (Tces)-protected carbamimidate nitrene precursor, coupled with the appropriate ligand for silver, is essential for achieving the unexpected chemoselectivity between arene dearomatization and benzylic C(sp³)-H amination. Potential applications in the late-stage diversification of azepines to complex molecular scaffolds and diastereoselective hydrogenations to sp³-rich derivatives are also highlighted.