Pfitzinger reaction
From Wikipedia, the free encyclopedia
The Pfitzinger reaction (also known as the Pfitzinger-Borsche reaction) is the chemical reaction of isatin with base and a carbonyl compound to give substituted quinoline-4-carboxylic acids.[1][2]
Several reviews have been published.[3][4][5]
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[edit] Reaction mechanism
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).
[edit] Variations
[edit] Halberkann variant
Reaction of N-acyl isatins with base gives 2-hydroxy-quinoline-4-carboxylic acids.[6]
[edit] References
- ^ Pfitzinger, W. J. Prakt. Chem. 1886, 33, 100.
- ^ Pfitzinger, W. J. Prakt. Chem. 1888, 38, 582.
- ^ Manske, R. H. Chem. Rev. 1942, 30, 126. (Review)
- ^ Bergstrom, F. W. Chem. Rev. 1944, 35, 152. (Review)
- ^ Shvekhgeimer, M. G.-A. Chemistry of Heterocyclic Compounds 2004, 40, 257-294. (Review, doi:10.1023/B:COHC.0000028623.41308.e5 )
- ^ Halberkann, J. Ber. 1921, 54, 3090.
