Amine/ammonium buffering enables efficient anti-Markovnikov hydroamination of olefins with alkylamines.

The hydroamination of alkenes represents a highly desirable and powerful strategy in synthetic chemistry for the direct construction of alkylamines from abundant starting materials. However, excess alkenes are typically required for anti-Markovnikov hydroamination of unactivated alkenes with alkylamines, significantly limiting its general utility in synthesis, especially for complex and expensive alkenes. In addition, significant enantiopurity erosion occurs when using α-chiral alkylamines as coupling partner. Herein, we present a solution to these challenges by developing an amine/ammonium buffering system under photocatalytic conditions. Key to this strategy is mitigating deprotonation of the involved aminium radical cation intermediate, formed through single electron oxidation of the associated alkylamine substrate, ensuring its effective addition to alkenes. The reaction works efficiently at a near-stoichiometric olefin-to-amine ratio while maintaining good yields. The method exhibits remarkable functional group tolerance, allows late-stage modification of complex alkenes and hydroamination of gaseous alkene, and largely preserves stereochemical fidelity in transformation of α-chiral alkylamine.