A microwave-assisted synthesis of triphenodioxazines [TPDOs]

A convenient and efficient method for the synthesis of triphenodioxazines [TPDOs] 1 by oxidative cyclisation of 2,5-bis-(arylamino)-3,6-dichlorocyclohexa-2,5-diene-1,4-diones 6 using potassium persulfate as the oxidising agent in 95‑97% sulfuric acid triggered by microwave irradiation is described.

Oxidative cyclisation of dianilides give symmetrical TPDOs in concd H2SO4/persulfate under microwave conditions [50 W], which are much milder conditions than previously used.