Mechanism (biology)

Quantum mechanics

Catalysis

Philosophy

Photochemistry

Reaction mechanism

Alkyl

Indole test

Synthon

Quenching (fluorescence)

Combinatorial chemistry

Physics

Organic chemistry

Photoredox catalysis

Epistemology

Fluorescence

Nitrile

Chemistry

Aryl

Photocatalysis

Ether

The Journal of Organic Chemistry

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 ligands were tuned to enable synthetically useful yields of radical coupling products. A range of indole substrates with alkyl, aryl, halogen, ester, and ether functional groups participate in the reaction, affording products in 16-90% yields. The reaction allows the rapid construction of synthetically useful cyanomethylindoles, products that otherwise require several synthetic steps.

Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism