The mesomeric effects of the benzofuroxan substituent in the preparation of phenazine N5,N10-dioxides are described. The electronic characteristics of the substituent in 5-substituted benzofuroxans determine the ratio of the 7- and 8-isomers of phenazine N5,N10-dioxides when substituted phenols are used.
phenazine N5,N10-dioxide; benzofuroxan tautomerism; mesomeric effect