Cyclohexadienone-phenol rearrangement

In a general reaction known as the cyclohexadienone phenol rearrangement cyclohexa dienones are converted to phenols under conditions of acid catalysis An example is... 

Chalais, S., Laszio, P., Mathy, A. Catalysis of the cyclohexadienone-phenol rearrangement by a Lewis-acidic clay system. Tetrahedron Lett. 1986, 27, 2627-2630. 

Earlier studies had shown that the cyclohexadienone 129 derived from the Hofmann degradation of mesembrenone on acid treatment underwent the expected cyclohexadienone-phenol rearrangement to give 130. Further interest in this system was stimulated by the need to develop controlled degradation schemes to ascertain labeling patterns at the C-2 and C-3 carbons... 

Vitullo, V. P. Cyclohexadienyl cations. II. Evidence for a protonated cyclohexadienone during the dienone-phenol rearrangement. J. Org. Chem. 1970, 35, 3976-3978. 

Cook, K. L., Waring, A. J. Kinetics of the dienone-phenol rearrangement of 4,4-dimethyl-2,5-cyclohexadienones. J. Chem. Soc., Perkin Trans. 21973, 88-92. 

Dienone-phenol rearrangement A rearrangement in which a cyclohexadienone that has two substituents at the 4 position, yields on treatment with an acid a phenol substituted at the 3 and 4 positions. 

Quinones - Quinone methides are produced on irradiation of /7-benzoqui-nones in the presence of the eneyne (267) in methylene chloride as solvent. 1,4-Naphthoquinones also afford quinone methides but unstable spirooxetenes were also detected. The photochemical addition of phenanthraquinone and ace-naphthenequinone to eneynes has also been studied. 1,4-Benzoquinones undergo addition to electron donating alkenes to yield spirooxetanes. The resultant cyclohexadienones are themselves photochemically reactive and irradiation converts these into dihydrobenzofurans via a dienone-phenol rearrangement. " ... 

Dienone-phenol rearrangements can also be achieved photochemically. For instance, cyclohexadienones 233 and 234 rearrange upon irradiation at 366 and 300 nm, respectively, to give phenols 235 and 236, respectively, in high yields (75-87%) (equation 169) °. ... 

Claisen rearrangement (Section 24 13) Thermal conversion of an allyl phenyl ether to an o allyl phenol The rearrange ment proceeds via a cyclohexadienone intermediate... 

A second process that occurs concurrently with the dissociation— redistribution process is an intermolecular rearrangement by which cyclohexadienone groups move along a polymer chain. The reaction maybe represented as two electrocycHc reactions analogous to a double Fries rearrangement. When the cyclohexadienone reaches a terminal position, the intermediate is the same as in equation 8, and enolization converts it to the phenol (eq. 9). 

The cycloaddition of picryl azide with phenoxyallene took place at the C1-C2 double bond of the allene exclusively to give the triazoline intermediate 97 [89]. This intermediate underwent a facile Claisen rearrangement to yield cyclohexadienone 98, which rapidly tautomerized to phenol 99. 

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