Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism

The direct cyanomethylation of indoles at the 2- or 3-position was achieved via photoredox catalysis. The versatile nitrile synthon is introduced as a radical generated from bromoacetonitrile, a photocatalyst, and blue LED as a light source. The mechanism of the reaction is explored by determination of the Stern–Volmer quenching constants. By combining photophysical data and mass spectrometry to follow the catalyst decomposition, the catalyst...