Baeyer indole synthesis

What is Baeyer indole synthesis?

The Baeyer indole synthesis, also referred to as the Baeyer-Emmerling indole synthesis, was initially discovered by Baeyer (Nobel Prize in Chemistry in 1905) and Emmerling in 1869. This synthetic process involves the alkaline reduction of o-nitro-cinnamic acid utilizing iron, leading to the formation of indole.

Baeyer indole synthesis - general reaction scheme - iron Fe KOH
Baeyer indole synthesis

While the Fischer indole synthesis is commonly considered the most adaptable strategy for synthesizing indole derivatives, a few alternative methods similar to the Baeyer indole synthesis have also been developed over time.


Baeyer, A. and Emmerling, A. (1869), Synthese des Indols. [Synthesis of indole.] Ber. Dtsch. Chem. Ges., 2: 679-682.