Traceless Aminoalkyl Radical-Induced Halogen-Atom Transfer for Minisci Reactions

Alkyl halides are a class of important organic feedstock with wide availability in organic synthesis. Minisci C-H alkylation is a classical radical-type reaction to effectively introduce alkyl groups into heteroaromatics. The attempt to utilize alkyl halides as radical precursors in Minisci reaction is challenging, which has attracted widespread attention. Although halogen-atom transfer (XAT) provides an available strategy to convert alkyl halides into corresponding carbon radicals, the usage of equivalent XAT reagents and excess oxidants is usually inevitable in Minisci reactions. Herein, we present a traceless aminoalkyl radical-induced XAT process for Minisci reaction, especially without the participation of excess XAT reagents and oxidants. This protocol is compatible with a wide array of sensitive functional groups. Mechanistic experiments indicated the formation of comparable aminoalkyl radicals occurred through SET reduction of protonated heteroaromatics, a process differing from the conventional oxidation method used to generate α-aminoalkyl radicals. Notably, this photocatalytic mode for such aminoalkyl radical generation and XAT-induced Minisci reaction contributes to a redox neutral strategy for coupling of two electrophilic molecules.