Gassman indole synthesis

The Gassman indole synthesis is a series of chemical reactions used to synthesize substituted indoles by addition of an aniline and a ketone bearing a thioether substituent.

This is a one-pot chemical reaction, and none of the intermediates are isolated. R₁ can be hydrogen or alkyl, while R₂ works best with aryl, but can also be alkyl. Electron-rich anilines, such as 4-methoxyaniline, tend to fail in this reaction.

The 3-position thiomethyl group is often removed using Raney nickel to give the 3-H-indole.