A Smiles Rearrangement as an Intermediate Step in the Formation of 8-Bromo-7-hydroxy-N-(4’ -N,N-diethylaminophenyl)-12H-benzo[b]phenothiazine-6,11-quinone 6-lmine from 2-(2’ -Aminophenylthio)-6-bromo-5-hydroxy-N-(4-/V,/V-diethylaminophenyl)-1,4-naphthoquinone 4-lmine

Heating 2-(2’-aminophenylthio)-6-bromo-5-hydroxy-N(4’-N,N-diethylaminophenyl)-1,4-naphthoquinone 1 in DMF-Py leads, along with the product of cyclization at the carbonyl group, to formation of 8-bromo-7-hydroxy- /V-(4’-N,N-diethylaminophenyl)-12H-benzo[b]phenothiazine-6,11-quinone 6-imine 4 via a Smiles rearrangement in the starting quinone imine and subsequent cyclization.