Polycondensed nitrogen heterocycles. Part 8. Pyrrolo[3,2-b]indole

Abstract

The reduction of the nitro-derivatives (4a–c) with iron–acetic acid leads to the pyrrolo[3,2-b]indoles (7a–c). This unusual indolization, in which displacement of the heterocycle amino-group occurs, is regarded as a nucleophilic attack by the 2-aminophenyl group on the pyrrole ring, and is an interesting example of intramolecular nucleophilic substitution in the pyrrole series.