Bronsted acid ionic liquid-catalyzed reductive Friedel-Crafts alkylation of indoles and cyclic ketones without using an external reductant

Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01299B, Communication
Amir Taheri, Bingbing Lai, Cheng Cheng, Yanlong Gu
C3-cycloalkylated indole was synthesized from indole and cyclic ketone in the absence of a reductant with the aid of an acid catalyst.
Bronsted acid ionic liquid-catalyzed reductive Friedel-Crafts alkylation of indoles and cyclic ketones without using an external reductant
In the absence of an external reductant, C3-cycloalkylated indole could be synthesized through reductive alkylation of indole with cyclic ketone using a sulfonyl-functionalized Brønsted acid ionic liquid as a catalyst. Water generated in the initial stage of the reaction played a key role in rendering the reductive coupling possible. The reaction proceeds most likely in a radical way.