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Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism
Ist Teil von
Journal of organic chemistry, 2018-08, Vol.83 (16), p.8926-8935
Ort / Verlag
United States: American Chemical Society
Erscheinungsjahr
2018
Link zum Volltext
Quelle
MEDLINE
Beschreibungen/Notizen
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.