Dienone

A dienone is a class of organic compounds with the general formula (R2C=CR)2C=O, where R is any substituent, but often H. They are formally "derived from 1,4-diene compounds by conversion of a –CH2– group into –C(=O)– group", resulting in "a conjugated structure". They are a kind of enone. The class includes some heterocyclic compounds.

Properties and occurrence

The parent member is divinyl ketone. It is a colorless liquid (b.p. 38-40 °C) that tends to polymerize upon standing.[1]

Dienones can arise via tautomerism of resorcinols and some hydroxypyridines.

Being multifunctional, dienones engage in many reactions. They are often good dienophiles. They function as ligands, forming metal-alkene complexes such as tris(dibenzylideneacetone)dipalladium(0).

Cyclic dienones

Extensive work has been reported on cyclic dienones. The parent of the seven-membered ring series is tropone. It is a not only a dienone but a trieneone.

Cyclohexadienones are a significant class of dienones, the premier members being the ortho- and para-quinones. Many cyclohexadienones convert to phenols.[2] In the dienone–phenol rearrangement, they convert to phenols[3] through the dienone–phenol rearrangement:[4]

The parent cyclopentadienone has only a fleeting existence under laboratory conditions, otherwise it dimerizes. The substituted derivative tetraphenylcyclopentadienone is however robust solid.[5]

See also

References

  1. ↑ . doi:10.1002/047084289X.rd475.pub2. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  2. ↑ Wipf, Peter; Jung, Jae-Kyu (1999). "Nucleophilic Additions to 4,4-Disubstituted 2,5-Cyclohexadienones: Can Dipole Effects Control Facial Selectivity?". Chemical Reviews. 99 (5): 1469–1480. doi:10.1021/cr9803838. PMID 11749453.
  3. ↑ Related to quinones, see for example the Zincke-Suhl reaction
  4. ↑ Advanced organic Chemistry, Reactions, mechanisms and structure 3ed. page Jerry March ISBN 0-471-85472-7
  5. ↑ Ogliaruso, Michael A.; Romanelli, Michael G.; Becker, Ernest I. (1965). "Chemistry of Cyclopentadienones". Chemical Reviews. 65 (3): 261–367. doi:10.1021/cr60235a001.
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