{{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 448615665 | ImageFile1 = 2,3-Dihydrothiazole.svg | ImageSize1 = 100px | ImageFile2 = 3-Thiazoline.svg | ImageSize2 = 100px | ImageFile3 = 4,5-Dihydrothiazole.svg | ImageSize3 = 100px | IUPACName = 2,3-Dihydrothiazole<br>2,5-Dihydrothiazole<br>4,5-Dihydrothiazole | OtherNames = 2,3-Dihydro-1,3-thiazole or 4-thiazoline<br>2,5-Dihydro-1,3-thiazole or 3-thiazoline<br>4,5-Dihydro-1,3-thiazole or 2-thiazoline |Section1={{Chembox Identifiers | index_label = (2,3) | index1_label = (2,5) | index2_label = (4,5) | CASNo = 504-79-0 | CASNo_Ref = {{cascite|correct|CAS}} | CASNo1 = 24576-55-4 | CASNo1_Ref = {{cascite|changed|CAS}} | CASNo2 = 504-79-0 | CASNo2_Ref = {{cascite|changed|CAS}} | PubChem = 151424 | PubChem1 = 15194654 | PubChem2 = 120269 | SMILES = C1=CSCN1 | SMILES1 = C1=NCSC1 | SMILES2 = C1CSC=N1 | InChI=1S/C3H5NS/c1-2-5-3-4-1/h1-2,4H,3H2 | InChIKey = OYJGEOAXBALSMM-UHFFFAOYSA-N | InChI1=1S/C3H5NS/c1-2-5-3-4-1/h1H,2-3H2 | InChIKey1 = JLPUISACQXFVRC-UHFFFAOYSA-N | InChI2=1S/C3H5NS/c1-2-5-3-4-1/h3H,1-2H2 | InChIKey2 = CBDKQYKMCICBOF-UHFFFAOYSA-N | ChemSpiderID = 133456 | ChemSpiderID1 = 10541467 | ChemSpiderID2 = 107368 }} |Section2={{Chembox Properties | C=3 | H=5 | N=1 | S=1 | Appearance = Colorless liquids | Density = | MeltingPt = | BoilingPtC = | BoilingPt_notes = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | NFPA-H = | NFPA-F = | NFPA-R = | AutoignitionPt = }} }}

'''Thiazolines''' ({{IPAc-en|T|aI|'|ae|z|oU|l|i:|n|z}}; 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.<ref>{{cite journal | last1 = Walsh | first1 = Christopher T. | last2 = Nolan | first2 = Elizabeth M. | year = 2008 | title = Morphing peptide backbones into heterocycles | journal = Proceedings of the National Academy of Sciences USA | volume = 105 | issue = 15| pages = 5655–5656 | doi = 10.1073/pnas.0802300105 | pmc = 2311349 | pmid=18398003| bibcode = 2008PNAS..105.5655W | doi-access = free }}</ref>

The name thiazoline originates from the Hantzsch–Widman nomenclature.

==Isomers== thumb|300px|left|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.<ref>{{cite journal | last1 = Willstätter | first1 = Richard | author-link = Richard Willstätter | last2 = Wirth | first2 = Theodor | year = 1909 | title = Über Thioformamid | url =https://zenodo.org/record/1426351 | journal = Chem. Ber. | volume = 42 | issue = 2| pages = 1908–1922 | doi = 10.1002/cber.19090420267 }}</ref> 2-Thiazolines are commonly prepared from 2-aminoethanethiols (e.g. cysteamine).<ref name=chemrev1>{{cite journal|last1=Gaumont|first1=Annie-Claude|last2=Gulea|first2=Mihaela|last3=Levillain|first3=Jocelyne|title=Overview of the Chemistry of 2-Thiazolines|journal=Chemical Reviews|date=11 March 2009|volume=109|issue=3|pages=1371–1401|doi=10.1021/cr800189z|pmid=19154153}}</ref> 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.<ref name=chemrev1 /> 2-Aminothiazoline-4-carboxylic acid is an intermediate in the industrial synthesis of L-cysteine.<ref>{{Ullmann|author=Karlheinz Drauz, Ian Grayson, Axel Kleemann, Hans-Peter Krimmer, Wolfgang Leuchtenberger, Christoph Weckbecker|year=2006|doi=10.1002/14356007.a02_057.pub2}}</ref>

==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== <references/>

Category:Thiazolines