The Synthesis of 5-Hydroxyindoles by the Nenitzescu Reaction
Abstract
The preparation of 5-hydroxyindole derivatives by the reaction of benzoquinones with certain enamines was suggested by the work of Nenitzescu who reported that the parent quinone, p-benzoquinone, reacts with ethyl 3-aminocrotonate in boiling acetone to yield ethyl 5-hydroxy-2-methylindole-3-carboxylate. The procedure was largely ignored until the 1950s when interest in melanin-related substances and cognition of serotonin as a 5-hydroxyindole derivative stimulated an exploration of this reaction.