Dakin West reaction

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The Dakin-West reaction is a named reaction of organic chemistry , after Henry Drysdale Dakin and Randolph West is named. It is a reaction to convert α - amino acids into α- acetamido - ketones using acetic anhydride and a base (e.g. pyridine ). Racemic aminoketones are usually formed . Schreiner and co-workers were the first to develop an enantioselective variant of this reaction .

Overview of the Dakin-West reaction

The response should not be confused with the Dakin response .

Reaction mechanism

The reaction mechanism is initiated by the acylation and activation of acid 1 and leads to mixed anhydride 3 . The amide acts as a nucleophile for the cyclization to azlactone 4 . A deprotonation leads to the anion 5 and a further acylation brings about a ring opening and the ester 7 is formed . After the formation of an acid 8 , decarboxylation takes place and the desired aminoketone 10 is formed.

Mechanism of the Dakin-West reaction

The reaction must be carried out under reflux with pyridine as the base and / or solvent . If catalytic amounts of 4-dimethylaminopyridine (DMAP) are added, the reaction also takes place at room temperature.

Individual evidence

  1. ^ HD Dakin, Randolph West: A General Reaction of Amino Acids. In: Journal of Biological Chemistry . 78, No. 1, 1928, pp. 91-104; Abstract .
  2. ^ HD Dakin, Randolph West: A General Reaction of Amino Acids. II. In: Journal of Biological Chemistry. 78, No. 3, 1928, pp. 745-756.
  3. ^ HD Dakin, Randolph West: Some Aromatic Derivatives of Substituted Acetylaminoacetones. In: Journal of Biological Chemistry. 78, No. 3, 1928, pp. 757-764.
  4. ^ Richard H. Wiley: The conversion of α-amino acids to oxazoles. In: The Journal of Organic Chemistry . 12, No. 1, 1947, pp. 43-46, doi : 10.1021 / jo01165a006 .
  5. ↑ GL Buchanan: The Dakin – West reaction. In: Chemical Society Reviews . 17, 1988, pp. 91-109, doi : 10.1039 / CS9881700091 .
  6. ^ Raffael C. Wende, Alexander Seitz, Dominik Niedek, Sören MM Schuler, Christine Hofmann: The Enantioselective Dakin – West Reaction . In: Angewandte Chemie International Edition . tape 55 , no. 8 , February 18, 2016, p. 2719–2723 , doi : 10.1002 / anie.201509863 .
  7. ↑ Rudolf Knorr, Rolf Huisgen: On the mechanism of the Dakin-West reaction, I The reaction of N-acyl-sec.-amino acids with acetic anhydride. In: Chemical Reports . 103, No. 8, 1970, pp. 2598-2610, doi : 10.1002 / cber.19701030831 .
  8. ↑ Norman L. Allinger, Grace L. Wang, Brian B. Dewhurst: Kinetic and mechanistic studies of the Dakin-West reaction. In: The Journal of Organic Chemistry. 39, No. 12, 1974, pp. 1730-1735, doi : 10.1021 / jo00925a029 .
  9. ↑ Richard H. Wiley, OH Borum: 3-Acetamido-2-Butanone In: Organic Syntheses . 33, 1953, p. 1, doi : 10.15227 / orgsyn.033.0001 ; Coll. Vol. 4, 1963, p. 5 ( PDF ).
  10. ↑ Gerhard Höfle, Wolfgang Steglich, Helmut Vorbrüggen: 4-Dialkylaminopyridines as Highly Active Acylation Catalysts. [New synthetic method (25)]. In: Angewandte Chemie International Edition in English. 17, No. 8, 1978, pp. 569-583, doi : 10.1002 / anie.197805691 .