| Cyclopentenone | |
|---|---|
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2-Cyclopenten-1-one |
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| Identifiers | |
| CAS number | 930-30-3 |
| PubChem | 13588 |
| ChemSpider | 12999 |
| ChEMBL | CHEMBL52190 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C5H6O |
| Molar mass | 82.04 g·mol−1 |
| Density | 0.98 g·mL−1 |
| Boiling point |
150 °C |
| Solubility in water | almost insoluble in water |
| Hazards | |
| Main hazards | Harmful |
| Flash point | 42 °C |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Cyclopentenone is a hydrocarbon with chemical formula C5H6O 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.[1]
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.
Cyclopentenones can be synthesized in a number of ways. Industrially, the most common procedures are elimination of α-bromo-cyclopentanone using lithium carbonate[2] and Claisen condensation-decarboxylation-isomerization cascades of unsaturated diesters as shown below.[3]
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.[4]
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.[5]