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Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism.

ABSTRACT: 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.

SUBMITTER: O'Brien CJ

PROVIDER: S-EPMC6097937 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism.

O'Brien Connor J CJ Droege Daniel G DG Jiu Alexander Y AY Gandhi Shivaani S SS Paras Nick A NA Olson Steven H SH Conrad Jay J

The Journal of organic chemistry 20180706 16

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 yie ...[more]

PMID: 29940725

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