Thiazoline

Thiazolines (or dihydrothiazoles) are a group of isomeric 5-membered heterocyclic compounds containing both sulfur and nitrogen in the ring. Although unsubstituted thiazolines are rarely encountered themselves, their derivatives are more common and some are bioactive. For example, in a common post-translational modification, cysteine residues are converted into thiazolines.[1]

Thiazoline

Names
IUPAC names 2,3-Dihydrothiazole 2,5-Dihydrothiazole 4,5-Dihydrothiazole
Other names 2,3-Dihydro-1,3-thiazole or 4-thiazoline 2,5-Dihydro-1,3-thiazole or 3-thiazoline 4,5-Dihydro-1,3-thiazole or 2-thiazoline
Identifiers
CAS Number	(2,3): 504-79-0 (2,5): 24576-55-4 (4,5): 504-79-0
3D model (JSmol)	(2,3): Interactive image (2,5): Interactive image (4,5): Interactive image
ChemSpider	(2,3): 133456 (2,5): 10541467 (4,5): 107368
PubChem CID	(2,3): 151424 (2,5): 15194654 (4,5): 120269
CompTox Dashboard (EPA)	(2,3): DTXSID70198448
InChI (2,3): InChI=1S/C3H5NS/c1-2-5-3-4-1/h1-2,4H,3H2 Key: OYJGEOAXBALSMM-UHFFFAOYSA-N (2,5): InChI=1S/C3H5NS/c1-2-5-3-4-1/h1H,2-3H2 Key: JLPUISACQXFVRC-UHFFFAOYSA-N (4,5): InChI=1S/C3H5NS/c1-2-5-3-4-1/h3H,1-2H2 Key: CBDKQYKMCICBOF-UHFFFAOYSA-N
SMILES (2,3): C1=CSCN1 (2,5): C1=NCSC1 (4,5): C1CSC=N1
Properties
Chemical formula	C3H5NS
Molar mass	87.14 g·mol^−1
Appearance	Colorless liquids
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

The name thiazoline originates from the Hantzsch–Widman nomenclature.

Isomers

2-Thiazoline, 3-Thiazoline and 4-Thiazoline (from left to right)

Three structural isomers of thiazoline exist depending on the position of the double bond. These forms do not readily interconvert and hence are not tautomers. Of these 2-thiazoline is the most common.

A fourth structure exists in which the N and S atoms are adjacent; this known as isothiazoline.

Synthesis

Thiazolines were first prepared by dialkylation of thioamides by Richard Willstatter in 1909.[2] 2-Thiazolines are commonly prepared from 2-aminoethanethiols (e.g. cysteamine).[3] They may also be synthesized via the Asinger reaction.

Applications

Many molecules contain thiazoline rings, one example being Firefly luciferin, the light-emitting molecule in fireflies. The amino acid cysteine is produced industrially from substituted thiazole.[3] 2-Aminothiazoline-4-carboxylic acid is an intermediate in the industrial synthesis of L-cysteine.[4]

See also

• Thiazole - an analogue with 2 double bonds
• Thiazolidine - an analogue with no double bonds
• Oxazoline - an analogue with O in place of S

References

1. Walsh, Christopher T.; Nolan, Elizabeth M. (2008). "Morphing peptide backbones into heterocycles". Proceedings of the National Academy of Sciences USA. 105 (15): 5655–5656. Bibcode:2008PNAS..105.5655W. doi:10.1073/pnas.0802300105. PMC 2311349. PMID 18398003.
2. Willstätter, Richard; Wirth, Theodor (1909). "Über Thioformamid". Chem. Ber. 42 (2): 1908–1922. doi:10.1002/cber.19090420267.
3. Gaumont, Annie-Claude; Gulea, Mihaela; Levillain, Jocelyne (11 March 2009). "Overview of the Chemistry of 2-Thiazolines". Chemical Reviews. 109 (3): 1371–1401. doi:10.1021/cr800189z. PMID 19154153.
4. Karlheinz Drauz, Ian Grayson, Axel Kleemann, Hans-Peter Krimmer, Wolfgang Leuchtenberger, Christoph Weckbecker (2006). Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_057.pub2.CS1 maint: multiple names: authors list (link)