Pfitzinger reaction

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Pfitzinger reaction
Named after W. Pfitzinger
Reaction type ring-condensation
ketone or aldehyde
potassium hydroxide
quinoline-4-carboxylic acid
Typical solvents protic

The Pfitzinger reaction (also known as the Pfitzinger-Borsche reaction) is the chemical reaction of isatin with base and a carbonyl compound to yield substituted quinoline-4-carboxylic acids.[1][2]

The Pfitzinger reaction

Several reviews have been published.[3][4][5]

Reaction mechanism[edit]

The mechanism of the Pfitzinger reaction

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 (or aldehyde) will react with the aniline to give the imine (3) and the enamine (4). The enamine will cyclize and dehydrate to give the desired quiniline (5).


Halberkann variant[edit]

The Halberkann variant of the Pfitzinger reaction

Reaction of N-acyl isatins with base gives 2-hydroxy-quinoline-4-carboxylic acids.[6]

See also[edit]


  1. ^ Pfitzinger, W. (1886). "Chinolinderivate aus Isatinsäure". J. Prakt. Chem. (in German). 33 (1): 100. doi:10.1002/prac.18850330110. 
  2. ^ Pfitzinger, W. (1888). "Chinolinderivate aus Isatinsäure". J. Prakt. Chem. (in German). 38 (1): 582–584. doi:10.1002/prac.18880380138. 
  3. ^ Manske, R. H. (1942). "The Chemistry of Quinolines". Chem. Rev. 30 (1): 113–144. doi:10.1021/cr60095a006. 
  4. ^ Bergstrom, F. W. (1944). "Heterocyclic Nitrogen Compounds. Part IIA. Hexacyclic Compounds: Pyridine, Quinoline, and Isoquinoline". Chem. Rev. 35 (2): 77–277. doi:10.1021/cr60111a001. 
  5. ^ Shvekhgeimer, M. G.-A. (2004). "The Pfitzinger Reaction". Chem. Heterocycl. Compd. 40 (3): 257–294. doi:10.1023/B:COHC.0000028623.41308.e5. )
  6. ^ Halberkann, J. (1921). "Abkömmlinge der Chininsäure". Chem. Ber. (in German). 54 (11): 3090–3107. doi:10.1002/cber.19210541118.