Pfitzinger reaction

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The Pfitzinger reaction or Pfitzinger-Borsche reaction describes the synthesis of quinoline- 4-carboxylic acids from isatin and a carbonyl compound under the action of a base. It goes back to the German organic chemists Wilhelm Pfitzinger ( University of Leipzig , 1886, 1888) and Walther Borsche (1877–1950; Georg-August University of Göttingen , 1914).

Pfitzinger reaction

Several reviews have been published.

Reaction mechanism

Reaction mechanism of the Pfitzinger reaction

The reaction of isatin with a base such as potassium hydroxide hydrolyzes the amide bond and gives the keto acid 2. This intermediate can be isolated, but this is generally bypassed. A ketone or aldehyde (R 1 = H) then condenses with the aniline to form imine 3, which is in equilibrium with enamine 4 , and quinoline 5 is formed in a cyclocondensation .

Half-can variant

Halberkann variant of the Pfitzinger reaction

The reaction of N- acylisatines with base gives 2-hydroxyquinoline-4-carboxylic acids. The German pharmacist Philipp Josef Halberkann (1880–1952) discovered this reaction variant .

See also

Individual evidence

  1. ^ Wilhelm Pfitzinger: Quinoline derivatives from isatic acid . In: Journal for practical chemistry . tape 33 , no. 1 , 1886, p. 100 , doi : 10.1002 / prac.18850330110 .
  2. ^ Wilhelm Pfitzinger: Quinoline derivatives from isatic acid . In: Journal for practical chemistry . tape 38 , no. 1 , 1888, p. 582-584 , doi : 10.1002 / prac.18880380138 .
  3. ↑ Walther Borsche, Wilhelm Jacobs: Investigations on Isatin and related compounds . I. In: Reports of the German Chemical Society . tape 47 , no. 1 , 1914, p. 354-363 , doi : 10.1002 / cber.19140470155 .
  4. ^ Richard H. F. Manske : The Chemistry of Quinolines . In: Chemical Reviews . tape 30 , no. 1 , 1942, p. 126 (113-144) , doi : 10.1021 / cr60095a006 (review).
  5. ^ Francis William Bergstrom : Heterocyclic Nitrogen Compounds . Part II A. Hexacyclic Compounds: Pyridines, Quinolines, and Isoquinolines. In: Chemical Reviews . tape 35 , no. 2 , 1944, pp. 152 (77-277) , doi : 10.1021 / cr60111a001 .
  6. ↑ Mai-Genrikh A. Shvekhgeimer ( Май-Генрих А. Швехгеймер ): The Pfitzinger Reaction . In: Chemistry of Heterocyclic Compounds . tape 40 , no. 3 , 2004, p. 257-294 , doi : 10.1023 / B: COHC.0000028623.41308.e5 (Review).
  7. ↑ Josef Halberkann: derivatives of quininic acid . In: Chemical Reports . tape 54 , no. 11 , 1921, pp. 3090-3107 , doi : 10.1002 / cber.19210541118 .