Thiazolines

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Thiazolines (dihydrothiazoles) are heterocyclic compounds whose five-membered ring contains one sulfur atom and one nitrogen atom as well as a double bond in the ring. The heteroatoms sulfur and nitrogen are in the 1,3-position to each other, the sulfur atom being assigned the 1 position and the nitrogen atom the 3 position. Depending on the position of the double bond in the heterocyclic ring, there are several isomeric thiazolines:

Isomers 2-thiazolines, 3-thiazolines and 4-thiazolines (from left to right)
  • 2-Thiazolines (alternative name: 4,5-Dihydrothiazole) contain a C = N double bond between the carbon atom 2 and the nitrogen atom
  • 3-Thiazolines (alternative name: 2,5-Dihydrothiazole) contain a C = N double bond between the carbon atom 4 and the nitrogen atom
  • 4-thiazolines (alternative name: 2,3-dihydrothiazoles) contain a C = C double bond between carbon atoms 4 and 5.

The sulfur-like odor of the 3-thiazolines is perceived as unpleasant and is particularly penetrating among the poorly substituted representatives.

synthesis

2-Thiazolines are formed by the reaction of cysteamine (2-aminoethanethiol) with nitriles . When other 1,2-aminomercaptans react with nitriles or carboxylic acid esters, substituted 2-thiazolines are formed. The synthesis of the 3-thiazolines takes place by the Asinger reaction or variants of this reaction. The synthesis of sterically uniform chiral 3-thiazolines starting from enantiomerically pure aldoses is described in the literature. 4-Thiazolines can be synthesized from 3-thiazolines, but other preparative methods for the production of this heterocycle are also known.

See also

Individual evidence

  1. ^ Richard Kuhn and F. Drawert, Liebigs Annalen der Chemie 590 , 55 (1954).
  2. ↑ Syntheses with ketones, sulfur and ammonia or amines and chemical behavior of the reaction products by Heribert Offermanns and Friedrich Asinger , Westdeutscher Verlag, Cologne and Opladen, 1966.
  3. ^ Karlheinz Drauz, Hans Günter Koban, Jürgen Martens and Werner Schwarze : Phosphonic and Phosphinic Acid Analogs of Penicillamine , Liebigs Annalen der Chemie 1985, 448–452.
  4. ↑ Imre Schlemminger, Hans-Hermann Janknecht, Wolfgang Maison, Wolfgang Saak, Jürgen Martens: Synthesis of the First Enantiomeric Pure 3-Thiazolines via Asinger Reaction , Tetrahedron Letters 41 (2000), 7289-7292.
  5. ↑ Jürgen Martens and Hans-Hermann Janknecht: N-Acyl-4-thiazoline from 3-thiazolines , Phosphorus, Sulfur, and Silicon 61 (1991) 173-176.
  6. ^ RC Elderfield: Heterocyclic Compounds , John Wiley & Sons, New York, 1957, Volume V, p. 677.