Pfitzinger reaction | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Named after | Wilhelm Pfitzinger | ||||||||||||
Reaction type | ring-condensation | ||||||||||||
Reaction | |||||||||||||
| |||||||||||||
Conditions | |||||||||||||
Typical solvents | protic | ||||||||||||
Identifiers | |||||||||||||
RSC ontology ID | RXNO:0000109 | ||||||||||||
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](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Pfitzinger_Reaction_Scheme.png/400px-Pfitzinger_Reaction_Scheme.png)
Several reviews have been published.[3][4][5]
Reaction mechanism
[edit]![The mechanism of the Pfitzinger reaction](https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Pfitzinger_Reaction_Mechanism.png/650px-Pfitzinger_Reaction_Mechanism.png)
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 quinoline (5).
Variations
[edit]Halberkann variant
[edit]![The Halberkann variant of the Pfitzinger reaction](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Pfitzinger_Halberkann_Modification_Scheme.png/350px-Pfitzinger_Halberkann_Modification_Scheme.png)
Reaction of N-acyl isatins with base gives 2-hydroxy-quinoline-4-carboxylic acids.[6]
See also
[edit]- Camps quinoline synthesis
- Friedländer synthesis
- Niementowski quinazoline synthesis
- Doebner reaction
- Talnetant, Cinchocaine
References
[edit]- ^ Pfitzinger, W. (1886). "Chinolinderivate aus Isatinsäure". J. Prakt. Chem. (in German). 33 (1): 100. doi:10.1002/prac.18850330110.
- ^ Pfitzinger, W. (1888). "Chinolinderivate aus Isatinsäure". J. Prakt. Chem. (in German). 38 (1): 582–584. doi:10.1002/prac.18880380138.
- ^ Manske, R. H. (1942). "The Chemistry of Quinolines". Chem. Rev. 30 (1): 113–144. doi:10.1021/cr60095a006.
- ^ 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.
- ^ Shvekhgeimer, M. G.-A. (2004). "The Pfitzinger Reaction". Chem. Heterocycl. Compd. 40 (3): 257–294. doi:10.1023/B:COHC.0000028623.41308.e5. S2CID 97698676.)
- ^ Halberkann, J. (1921). "Abkömmlinge der Chininsäure". Chem. Ber. (in German). 54 (11): 3090–3107. doi:10.1002/cber.19210541118.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction