Organic Reactions in Water: A Distinct Approach for the Synthesis of Quinoline Derivatives Starting Directly from Nitroarenes

Three-component reactions of nitroarenes, aldehydes, and phenylacetylene in the presence of indium in dilute hydrochloric acid produce the corresponding quinoline derivatives under reflux. The conversion in this one-pot synthesis involves the following steps: (i) reduction of the nitroarenes to anilines, (ii) coupling of the anilines, aldehydes, and phenylacetylene, (iii) cyclization of the resulting species, and (iv) dehydrogenation of the cyclic intermediates. Several new quinolines have been prepared.