Pentamethylbenzene has been oxidised with peroxytrifluoroacetic acid–boron fluoride in methylene chloride to give mainly a mixture of pentamethylcyclohexa-2, 4-dienones. The 2, 4, 5, 6, 6,-and 2, 3, 4, 6, 6-pentamethyl isomers were formed in yields of 33 and 37%, respectively, and the 3, 4, 5, 6, 6-pentamethyl isomer was forme
