ipso Nitration. XXIV. Nitration of 2-methylphenols. Formation and rearrangement of 6-methyl-6-nitrocyclohexa-2,4-dienones

Abstract

Nitration of o-cresol and some mono-, di-, and trimethyl derivatives in acetic anhydride at −60 °C gives 6-methyl-6-nitrocyclohexa-2,4-dienones. The dienones are more labile than the isomeric 4-methyl-4-nitrocyclohexa-2,5-dienones and, if the 2-position of the dienone is not blocked, undergo regiospecific rearrangement to 6-nitro-o-cresols. 2,3,6-Trimethyl- and 2,3,5,6-tetramethylphenol also give a 2,5-dienone with nitro attached to a secondary carbon.