Facile convergent route to indoloquinolines

A convergent route to indoloquinolines is developed through aldol condensation. This two-step method utilizes commercially available 2-oxoindole and o-nitrobenzaldehyde as starting materials. Chromatography-free method is accomplished for preparing several derivatives of indoloquinolines with desirable aromatic substitutions on indole as well as quinoline ring.