From nitrobenzenes to substituted tetrahydroquinolines in a single step by a domino reduction/imine formation/aza-diels-alder reaction.

The three-component reaction between a nitrobenzene, an aldehyde, and a dienophile in the presence of iron powder as a reductant and montmorillonite K10 as a catalyst in aqueous citric acid delivers the products of an aza-Diels-Alder (Povarov) reaction with high endo-selectivity and yields up to 99%.