Non-Directed, Copper Catalyzed Benzylic C-H Amination Avoiding Substrate Excess
We report the development of a benzylic C-H amination protocol that addresses two common drawbacks in non-directed, intermolecular benzylic C-H aminations: (i) the need to use an excess of substrate and (ii) the limitation to only introduce one type of nitrogen source. Key to this discovery is the use of the strong oxidant N-fluorobenzenesulfonimide (NFSI) in combination with a Cu/diimine ligand catalyst system and an added nitrogen nucleophile. The established conditions allow to lower the C-H substrate loading to 1.0 equivalent and provide up to 95% yield of C-H amination product. Furthermore, sulfonamides and benzamides can be employed as nitrogen sources/nucleophiles, resulting in access to a diverse product scope.