Cyclobutenone
Chemical compound
From Wikipedia, the free encyclopedia
Cyclobutenone is a chemical compound with the formula C4H4O. It is a highly strained cyclic enone which exhibits significant chemical reactivity. Notable reactions of cyclobutenone include acting as a Michael acceptor, a dienophile for Diels-Alder reactions, and a regioselective substrate for activation of C−C bonds. Electrocyclic ring opening of cyclobutenones yields vinylketenes, which serve as reactive intermediates in cycloaddition reactions.[1]
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| Names | |
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| IUPAC name
Cyclobut-2-en-1-one | |
| Other names
2-Cyclobutene-1-one | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| EC Number |
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| MeSH | cyclobutenone |
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| C4H4O | |
| Molar mass | 68.075 g·mol−1 |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H302, H315, H319, H335 | |
| P280, P305+P351+P338 | |
| Safety data sheet (SDS) | A2B Chem |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
Unsubstituted cyclobutenone can be prepared by dehydrohalogenation of 3-bromocyclobutanone. The bromocyclobutanone precursor can be prepared by decarboxylation of 3-oxocyclobutanecarboxylic acid with bromine and mercury(II) oxide.[2]
Substituted cyclobutenones can be prepared by cycloaddition of an alkyne and ketene, such as the [2+2] cycloaddition of 1-hexyne and dichloroketene (generated in situ from trichloroacetyl chloride) to 3‑butyl‑4,4‑dichlorocyclobutenone.[3]
Reactivity
Cyclobutenone has been described as an "unusually reactive" dienophile, substantially more reactive than other enone rings like cyclopentenone and cyclohexenone.[4]