| Iupacname | Cyclobut-2-en-1-one |
|---|---|
| Othernames | 2-Cyclobutene-1-one |
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\sC bonds. Electrocyclic ring opening of cyclobutenones yields vinylketenes, which serve as reactive intermediates in cycloaddition reactions.[1]
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 3butyl4,4dichlorocyclobutenone.[3]
Reactivity
Cyclobutenone has been described as an "unusually reactive" dienophile, substantially more reactive than other enone rings like cyclopentenone and cyclohexenone.[4]
Sources
- ^ Chen, Peng-hao & Dong, Guangbin (2016). "Cyclobutenones and Benzocyclobutenones: Versatile Synthons in Organic Synthesis". Chemistry – A European Journal. 22 (51): 18290–18315. doi:10.1002/chem.201603382. PMC 5503213. PMID 27620805
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- ^ Paton, Robert S.; Kim, Seonah; Ross, Audrey G.; Danishefsky, Samuel J.; Houk, K. N. (2011). "Experimental Diels–Alder Reactivities of Cycloalkenones and Cyclic Dienes Explained through Transition-State Distortion Energies". Angewandte Chemie International Edition. 50 (44): 10366–10368. doi:10.1002/anie.201103998. PMID 21910195