<i>N</i>,<i>N</i>,<i>N</i>’,<i>N</i>’‑Tetramethylethylenediamine-Enabled\nPhotoredox-Catalyzed C–H Methylation of <i>N</i>‑Heteroarenes

Abstract

Aiming\nat the valuable methylation process, readily available and\ninexpensive <i>N</i>,<i>N</i>,<i>N′</i>,<i>N′</i>-tetramethylethylenediamine (TMEDA) was\nfirst identified as a new methyl source in photoredox-catalyzed transformation\nin this work. By virtue of this simple methylating reagent, a facile\nand practical protocol for the direct C–H methylation of <i>N</i>-heteroarenes was developed, featuring mild reaction conditions,\nbroad substrate scope, and scalability. Mechanistic studies disclosed\nthat a sequential photoredox, base-assisted proton shift, fragmentation,\nand tautomerization process was essentially involved.