The dienone-phenol rearrangement

The female sex hormone oestrone is the metabolic product of another hormone, progesterone, itself made in the body from cholesterol. 

The dieneone-phenol rearrangement is also observed in numerous ring expansion processes (cf. Equation 9.71). 

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The driving force in the overall reaction (the dienone-phenol rearrangement) is of... 

In 1979, workers investigating " the dienone-phenol rearrangement treated (3) with acetic anhydride and got an unknown compound believed to be (4), Treatment with strong acid gave (5), they supposed, but they wanted to synthesise an authentic sample of (5) to check their assignment. This is a tricky problem... 

Rearrangement of di- and poly-alkylbenzenes also takes place readily in the presence of Lewis acid catalysts (p. 163), and in the dienone/phenol rearrangement (p. 115). 

A rearrangement essentially akin to a reversal of the pinacol/ pinacolone change, a retro pinacol reaction, is the dienone/phenol rearrangement,... 

Besides aromatization, the energy resulting from relief of cyclic strain can be a driving force of the dienone-phenol rearrangement. Thus, it was reported that dienone 302 is... 

Unusual examples of the dienone-phenol rearrangement include the reactions of 1,4-dihydrosilabenzene 361 which rearranges in two directions upon treatment with BCI3 or during purification on silica gel (equation 131)185. 

A number of studies of migratory aptitudes in the dienone-phenol rearrangement (6-5) are in accord with the above. For a discussion, see Fischer Henderson 7. Chem. Soc., Chem. Commun. 1979, 279, and references cited therein. See also Palmer Waring 7. Chem. Soc,. Perkin Trans. 2 1979, 1089 Marx Hahn 7. Org. Chem. 1988, 53, 2866. 

The driving force in the overall reaction (the dienone-phenol rearrangement) is of course creation of an aromatic system.136 It may be noted that 50 and 51 are arenium ions (p. 502), the same as those generated by attack of an electrophile on a phenol.137 Sometimes, in the reaction of a phenol with an electrophile, a kind of reverse rearrangement (called the phenol-dienone rearrangement) takes place, though without an actual migration.I3B An example is... 

The dienone-phenol rearrangement 8-20 Cleavage of aryl ketones with per-acids (Baeyer-Villiger)... 

A careful study of the dienone-phenol rearrangement in vitro of pakistanamine (60), which is the sole proaporphine-benzylisoquinoline alkaloid presently known,... 

For reviews of the dienone phenol rearrangement, see refs. [51] [52]. Further reference [53]. 

Protonated carbonyl compounds can be electron sinks too (remember the dienone-phenol rearrangement from Chapter 37 ), and this bicyclic methoxy ketone fragments to a seven-membered ring in acid. Note the same 1,2,3,4 arrangement, with the bond between carbon atoms 2-3 fragmenting. 

The dienone-phenol rearrangement of androsta-l,4,6-trien-3,ll,17-trione has been shown to lead to two major products, the AB-aromatic acetate (180 X = O) and the corresponding lla-ol (180 X = a-OH,H). Oxidation of the naphthol (180 ... 

Oxidative reanangements of dienes are related to the dienone/phenol rearrangement, which is discussed in Volume 3, Chapter 3.5. The examples discussed here are limited to cyclohexadienes, and the driving force for the rearrangement is aromatization. 

The dehydration of dimols [e.g. 29) under acid-catalysed conditions gives rearranged products containing an aromatic system [lyi] and is mechanistically similar to the dienone-phenol rearrangement [172]. Protonation of the hydroxyl group is followed by loss of a molecule of water to give the... 

The reaction path may, however, depend upon reaction conditions. Mineral acids or BF3 are reported to give only 4-methyl derivatives, but anhydrous aluminium chloride or neutral alumina yielded mixtures of the 4-methyl (31) and i-methyl (32) derivatives [1777. No satisfactory explanation has yet been offered for these observations. As in the dienone-phenol rearrangement, a 6,7-double bond (33) results in preferential methyl migration to give the i-methyl derivative... 

Many rearrangement reactions are initiated by BF3 complexes in the presence of acetic anhydride, including the synthesis of functionalized and optically active pyrans from (+)-(/ ,R)-diethyl tartrate (Eq. 41) [74]. Other examples include the conversion of bicyclic into monocyclic [75] and tricyclic into bicyclic systems [76], the acetolysis of glycosides resulting in the formation of the fully acetylated acyclic derivative [77], and the unusual migration of nitrogen in the dienone-phenol rearrangement of an N-methoxy-/ -lactam [78]. 

The dienone-phenol rearrangement is so named because the starting material is a dienone and the product is a phenol. 

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