The rearrangement, in trifluoroacetic acid at 38.5°, of two series of 4,4-disubstituted cyclohexadienones to give 3,4-disubstituted phenols has been studied. In the first series, a carbethoxy group is placed in intramolecular migratory competition with other common substituents (Me, Et, Ph, z'-Pr, Bz). The carbethoxy group is found to migrate in preference to Me, Et, or Ph with relative rates of 1:0.45:135. In the case of the z'-Pr and Bz substituted compounds, fragmentation occurs instead of rearrangement to give 4-carbethoxyphenol and the z'-Pr and Bz carbonium ions, respectively. In the second series, intermolecular kinetic comparisons of a series of compounds in which the substituents migrate in a methyl-substituted framework allows one to assess the migration tendency, as defined by Stiles and Mayer, of the substituents in the dienone system. The order found is Me < COOEt < Et < Ph
Die α‐Formylester (I) werden mit dem Vinylketon (II) zu den entsprechenden Oxoestern umgesetzt und ergeben in Gegenwart von Piperidiniumacetat die Cyclohexenone (III).
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