 In this reaction aniline or an aniline derivative first reacts with malonic acid derivative "ethyl ethoxymethylenemalonate" with substitution of the ethoxy group by nitrogen.A benzannulation takes place by application of heat to a quinoline.The ester group is hydrolysed by sodium hydroxide to the carboxylic acid and decarboxylation again by application of heat to 4-hydroxyquinoline.