Thiazole

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Thiazole
Image:Thiazole numbering.png
Image:Thiazole3d.png
Identifiers
CAS number 288-47-1
SMILES N1=CSC=C1
Properties
Boiling point

116-118 °C

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Thiazole, or 1,3-thiazole, is a clear to pale yellow flammable liquid and pyridine-like odor with the molecular formula C3H3NS. It is a 5-membered ring, in which two of the vertices of the ring are nitrogen and sulfur, and the other three are carbons [1].

Thiazole is used for manufacturing biocides, fungicides, pharmaceuticals, and dyes.

Thiazoles and thiazolium salts

Thiazoles are a class of organic compounds related to azoles with a common thiazole functional group.

Thiazoles are aromatic

The thiazole moiety is a crucial part of vitamin B1 (thiamine) and epothilone. Other important thiazoles are Benzothiazoles for example the firefly chemical luciferin.

When the amino atom is alkylated the resulting thiazolium salt is a salt. Thiazolium salts are catalysts in the Stetter reaction and the Benzoin condensation. Thiazole dyes are used for dying cotton.

Oxazoles are related compound with sulfur replaced by oxygen. Thiazoles are well represented in biomolecules, oxazoles are not.

Organic synthesis

Various laboratory methods exist for the organic synthesis of thiazoles.

Organic reactions

Thiazoles are characterized by larger pi-electron delocalization than the corresponding oxazoles and have therefore greater aromaticity. This is evidenced by the position of the ring protons in proton NMR (between 7.27 and 8.77 ppm) clearly indicating a strong diamagnetic ring current.

The calculated pi-electron density marks C5 as the primary electrophilic site and C2 as the nucleophilic site.

The reactivity of a thiazole can be summarized as follows:

2-(trimethylsiliyl)thiazole [4] (with a trimethylsilyl group in the 2-position) is a stable substitute and reacts with a range of electrophiles such as aldehydes, acyl halides and ketenes.
  • Thiazoles can react in cycloadditions but in general at high temperatures due to favorable aromatic stabilization of the reactant. Diels-Alder reactions with alkynes are followed by extrusion of sulfur and the endproduct is a pyridine. In one study [3] a very mild reaction of a 2-(dimethylamino)thiazole with dimethyl acetylenedicarboxylate (DMAD) to a pyridine was found to proceed through a zwitterionic intermediate in a formal [2+2]cycloaddition to a cyclobutene, then to a 1,3-thiazepine in an 4-electron electrocyclic ring openening and then to a 7-thia-2-azanorcaradiene in an 6-electron electrocyclic ring closing before extruding the sulfur atom.

References

  1. The Chemistry of Heterocycles : Structure, Reactions, Syntheses, and Applications Theophil Eicher, Siegfried Hauptmann ISBN 3-527-30720-6
  2. George Schwarz (1955). "2,4-Dimethylthiazole". Org. Synth.; Coll. Vol. 3: 332. 
  3. 3.0 3.1 Mateo Alajarín, José Cabrera, Aurelia Pastor, Pilar Sánchez-Andrada, and Delia Bautista (2006). "On the [2+2] Cycloaddition of 2-Aminothiazoles and Dimethyl Acetylenedicarboxylate. Experimental and Computational Evidence of a Thermal Disrotatory Ring Opening of Fused Cyclobutenes". J. Org. Chem. 71 (14): 5328 - 5339. doi:10.1021/jo060664c.
  4. 4.0 4.1 Alessandro Dondoni and Pedro Merino (1998). "Diastereoselective Homologation of D-(R)-Glyceraldehyde Acetonide using 2-(Trimethylsilyl)thiazole". Org. Synth.; Coll. Vol. 9: 952. 
  5. Elizabeta Amir and Shlomo Rozen (2006). "Easy access to the family of thiazole N-oxides using HOF·CH3CN". Chemical Communications 2006: 2262 - 2264. doi:10.1039/b602594c.
it:Tiazolo

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Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .

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