A new synthetic route to 1-chlorophenazines. The electrochemical monodechlorination of 3,3,6,6-tetrachloro-1,2-cyclohexanedione as a key step

A convenient new method for the synthesis of 1-chlorophenazines has been established. The first step involves an almost quantitative electrochemical reduction of 3,3,6,6-tetrachloro-1,2-cyclohexanedione 1 to 3,6,6-trichloro-2-hydroxy-2-cyclohexen-1-one 2. The reaction of 2 with aromatic 1,2-diamines followed by aromatisation through treatment with 2,6-lutidine leads to the title compounds in high yields.