The reaction in which N-acyl o-alkylanilines undergo intramolecular ring closure to generate the corresponding substituted indole under strong base conditions is called the Madelung indole synthesis reaction.
Indole is a compound of pyrrole and benzene in parallel. Also known as benzopyrrole. There are two ways of merging, called indole and isoindole. Indole and its homologues and derivatives are widely found in nature, mainly in natural flower oils such as jasmine, bitter orange, daffodil, vanilla, etc.
