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Cyclopentenone

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Cyclopentenone
Names
IUPAC name 2-Cyclopenten-1-one
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.012.012 Edit this at Wikidata
PubChem CID
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C5H6O/c6-5-3-1-2-4-5/h1,3H,2,4H2Key: BZKFMUIJRXWWQK-UHFFFAOYSA-N
SMILES
  • C1CC(=O)C=C1
Properties
Chemical formula C5H6O
Molar mass 82.04 g·mol
Density 0.98 g·mL
Boiling point 150 °C
Solubility in water almost insoluble in water
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Harmful
Flash point 42 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Cyclopentenone is a hydrocarbon with chemical formula Template:Carbon5Template:Hydrogen6Template:Oxygen and CAS number 930-30-3. It is structurally similar to cyclopentanone, with the additional feature of α-β unsaturation in the ring system. Cyclopentenone belongs to the cycloalkene (alkenes which have one or more rings of carbon atoms) class of compounds and is also a ketone (it possesses a carbonyl functional group). It is a liquid at room temperature with a boiling point of 150 °C. It has been isolated from pressure-cooked pork liver by simultaneous steam distillation and continuous solvent extraction.

The term cyclopentenone may also refer to a structural motif wherein the cyclopentenone moiety is a subsection of a larger molecule. In this regard, cyclopentenones are found in a large number of natural products, including jasmone, the aflatoxins, and several prostaglandins.

Synthesis

Cyclopentenones can be synthesized in a number of ways. Industrially, the most common procedures are elimination of α-bromo-cyclopentanone using lithium carbonate and Claisen condensation-decarboxylation-isomerization cascades of unsaturated diesters as shown below.

Industrial synthesis of cyclopentenone
Industrial synthesis of cyclopentenone

As a functional group, the synthesis of cyclopentenones is accomplished in a variety of other ways, including the Nazarov cyclization reaction from divinyl ketones, Saegusa-Ito oxidation from cyclopentanones, ring-closing metathesis from the corresponding dienes, oxidation of the corresponding cyclic allylic alcohols, and the Pauson-Khand reaction from alkenes, alkynes, and carbon monoxide.

Reactions

As an enone, cyclopentenone undergoes the typical reactions of α-β unsaturated ketones, including nucleophilic conjugate addition, the Baylis-Hillman reaction, and the Michael reaction. Cyclopentenone also functions as an excellent dienophile in the Diels-Alder reaction, reacting with a wide variety of dienes. In one example, a Danishefsky-type diene is reacted with a cyclopentenone to yield a fused tricyclic system en route to the synthesis of coriolin.

Cyclopentenone in the synthesis of coriolin
Cyclopentenone in the synthesis of coriolin

References

  1. Mussinan,C.J.; Walradt, J.P. (1974), J. Agric. Food Chem., 22 (5): 827–831, doi:10.1021/jf60195a002 {{citation}}: Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  2. Process for producing 2-bromocyclopentanone, 2004-05-12 {{citation}}: Unknown parameter |country-code= ignored (help); Unknown parameter |inventor-first= ignored (help); Unknown parameter |inventor-last= ignored (help); Unknown parameter |inventor2-first= ignored (help); Unknown parameter |inventor2-last= ignored (help); Unknown parameter |patent-number= ignored (help)
  3. Process for preparing cyclopentenone, 2004-11-25 {{citation}}: Unknown parameter |country-code= ignored (help); Unknown parameter |inventor-first= ignored (help); Unknown parameter |inventor-last= ignored (help); Unknown parameter |inventor2-first= ignored (help); Unknown parameter |inventor2-last= ignored (help); Unknown parameter |inventor3-first= ignored (help); Unknown parameter |inventor3-last= ignored (help); Unknown parameter |inventor4-first= ignored (help); Unknown parameter |inventor4-last= ignored (help); Unknown parameter |patent-number= ignored (help)
  4. Organic Reactions Portal "Cyclopentenone synthesis"
  5. Danishefsky, S.; Zamboni, R.; Kahn, M.; Etheredge, S.J. (1980), J. Am. Chem. Soc., 102 (6): 2097–2098, doi:10.1021/ja00526a061 {{citation}}: Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
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