Wohl‐Aue Reaction

The preparation of phenazine and phenazine N ‐oxide from the condensation of an aromatic nitro compound with an aniline in presence of a strong base is generally known as the Wohl–Aue reaction. This reaction suffers from the low yields of phenazines and corresponding N ‐oxides and the complication from other side products. It has been reported that yield can be increased when toluene is substituted for benzene as the solvent. The sterically unhindered phenazines can be directly oxidized to phenazine dioxide, whereas the sterically hindered ones (e.g., benzo[a]phenazine) can be converted only into mono‐oxides. This reaction is useful for the preparation of phenazine N ‐oxide and phenazine derivatives.