 This reaction was discovered by Max Conrad (1848–1920) and Leonhard Limpach (1852–1933) in 1887 while they were studying the synthesis of quinoline derivatives.The mechanism begins with an attack of aniline on the keto group of the β-ketoester to form a tetrahedral intermediate.The newly formed oxide is then twice protonated to form the Schiff base, which then undergoes keto-enol tautomerization before an electrocyclic ring closing.