N-Aryl Tetrahydroisoquinolines as Both Reagents and Substrates for Coupling with Alkyl Halides

This work presents a novel photocatalytic halogen atom transfer (XAT) strategy, enabling redox-neutral C(sp³)-C(sp³) coupling between N-aryl tetrahydroisoquinolines and unactivated alkyl halides. The strategy employs an α-aminoalkyl radical, generated in situ from N-aryl tetrahydroisoquinoline via single-electron transfer (SET) oxidation under photocatalytic conditions. This radical acts as a traceless XAT reagent to activate alkyl bromides/chlorides/iodides (C-X bond), forming key alkyl carbon radicals. Simultaneously, the same N-aryl tetrahydroisoquinoline molecule is converted into an iminium intermediate after the XAT event, which functions as an endogenous coupling partner to capture the alkyl radicals, ultimately forming C-C bonds. This transformation proceeds under redox-neutral conditions without external XAT reagents or stoichiometric reductants.