Japp-Klingemann reaction

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The Japp-Klingemann reaction is a name reaction in organic chemistry , which was named after its discoverers, the British chemist Francis Japp (1848–1925) and the German chemist Felix Klingemann (1863–1944). It is a chemical reaction used to make aryl hydrazones from β-keto esters or acids and aryldiazonium salts.

Overview reaction

In the Japp-Klingemann reaction, an aryl diazonium salt and a β-keto ester react to form an aryl hydrazone and a carboxylate .

Overview of the Japp-Klingemann reaction (ester)

mechanism

In the first step, the β-ketoester is deprotonated by a hydroxide ion . Thereafter, nucleophilic addition of the enolate to the aryl diazonium salt gives an azo compound . The intermediate could be isolated in a few cases. Usually the basic leads hydrolysis of the azo compound , but in situ to a tetrahedral intermediate, resulting in a carboxylic acid and a hydrazone decomposed anion. In the last step, the desired product arylhydrazone is formed by protonation .

Mechanism of the Japp-Klingemann reaction (ester)

use

By heating the products with strong acid, indoles are formed, analogous to the Fischer synthesis .

Use of the Japp-Klingemann reaction for indole synthesis

literature

  • Francis R. Japp, Felix Klingemann: About Benzolazo- and Benzolhydrazofettsäuren . In: Reports of the German Chemical Society . tape 20 , no. 2 , July 1, 1887, p. 2942-2944 , doi : 10.1002 / cber.188702002165 .
  • Francis R. Japp, Felix Klingemann: Knowledge of the benzene azo and benzene hydrazopropionic acids . In: Reports of the German Chemical Society . tape 20 , no. 2 , July 1, 1887, p. 3284-3286 , doi : 10.1002 / cber.188702002234 .
  • Francis R. Japp, Felix Klingemann: About so-called "mixed azo compounds" . In: Reports of the German Chemical Society . tape 20 , no. 2 , July 1, 1887, p. 3398-3401 , doi : 10.1002 / cber.188702002268 .
  • Francis R. Japp, Felix Klingemann: About the constitution of some so-called mixed azo compounds . In: Justus Liebig's Annals of Chemistry . tape 247 , no. 2 , January 1, 1888, p. 190-225 , doi : 10.1002 / jlac.18882470208 .
  • Robert R Phillips: The Japp-Klingemann Reaction . In: Organic Reactions . John Wiley & Sons, Inc., 2004, ISBN 978-0-471-26418-7 , doi : 10.1002 / 0471264180.or010.02 .
  • GA Reynolds, JA VanAllan: Methylglyoxal-ω-Phenylhydrazones In: Organic Syntheses . 32, 1952, p. 84, doi : 10.15227 / orgsyn.032.0084 ; Coll. Vol. 4, 1963, p. 633 ( PDF ).
  • RE Bowman, TG Goodburn, AA Reynolds: 1,3,4,5-tetrahydrobenz [cd] indoles and related compounds. Part I. A new synthesis of 3,4-dihydrobenz [cd] indol-5 (1H) -one (Uhle's ketone) . In: Journal of the Chemical Society, Perkin Transactions 1 . No. 0 , January 1, 1972, p. 1121-1123 , doi : 10.1039 / P19720001121 .
  • Michael D. Meyer, Lawrence I. Kruse: Ergoline synthons: Synthesis of 3,4-dihydro-6-methoxybenz [cd] indol-5 (1H) -one (6-methoxy-Uhle's ketone) and 3,4-dihydrobenz [ cd] indole-5 (1H) -one (Uhle's ketone) via a novel decarboxylation of indole-2-carboxylates . In: The Journal of Organic Chemistry . tape 49 , no. 17 , August 1, 1984, pp. 3195-3199 , doi : 10.1021 / jo00191a028 .

Individual evidence

  1. ^ László Kürti , Barbara Czakó: Strategic Applications of Named Reactions in Organic Synthesis. 1st edition. Elsevier Academic Press, Burlington / San Diego / London 2005, ISBN 0-12-369483-3 , p. 224.