Dopaquinone and Related Compounds: Reactions with o-Phenylenediamine

Abstract
The oxidation of 4-substituted catechols including DOPA with o-chloranil or cerium(IV) sulfate to give the corresponding o-benzoquinones was examined. The trapping of o-benzoquinones with o-phenylenediamine immediately after oxidation was successfully used to isolate 2-substituted phenazines, the substituents being –CH3, –CH(CH3)2, –(CH2)2CO2H, –(CH2)2CO2CH3, –CH=CHCO2H, –CH=CHCO2CH3, –(CH2)2NHCOC6H5, and –CH2CH(NHCOC6H5)CO2CH3. Dopaquinone was identified in a protected form.