Experiments on the synthesis of tetracycline. Part XIII. Oxidation of ring A model phenols to p-hydroxycyclohexadienones
Abstract
The reaction of phenols with cerium(IV) oxide–hydrogen peroxide to give hydroperoxycyclohexadienones is described. In particular 2,6-dihydroxy-3,4-dimethylbenzamide (V) is converted into 3-hydroperoxy-2-hydroxy-3,4-dimethyl-6-oxocyclohexa-1,4-dienecarboxamide (VII). The reagent system is shown to be an in situ source of singlet oxygen.