Pfitzinger reaction
The Pfitzinger reaction is the chemical reaction of isatin with base and a carbonyl compound to yield substituted quinoline-4-carboxylic acids.
Several reviews have been published.The reaction of isatin with a base such as potassium hydroxide hydrolyses the amide bond to give the keto-acid 2. This intermediate can be isolated, but is typically not. A ketone will react with the aniline to give the imine and the enamine. The enamine will cyclize and dehydrate to give the desired quiniline.Variations
Halberkann variant
Reaction of N-acyl isatins with base gives 2-hydroxy-quinoline-4-carboxylic acids.
