3-Indoleacetic acid (IAA) is a naturally occurring hydrophilic organic compound consists of an unsaturated aromatic ring that is commonly used in the synthesis of indolylated diarylmethanes, α-acetoxyl ketones, and Indolmethyl-Chromones via copper catalyzed coupling reactions.

3-Indoleacetic acid (IAA) can be used as a building block to synthesize ,(±) harmacine using 4,4-diethoxybutan-1-amine via an acid-catalyzed acyl iminium ion cyclization reaction.
(±)-Harmacine is a vital step in the synthesis of a variety of indole alkaloids and dopamine/serotonin receptor ligands. IAA can also be used in the preparation of alkaloid (±)-19-hydroxyibogamine.