Abstract The catalytic oxidative cyclocondensation of the o??aminophenols 1a–f was investigated. The oxidants used were air/laccase, H2O2/horseradish peroxidase, H2O2/ebselen (3), and TBHP/diphenyl diselenide 4. The products obtained were 2??amino??3 H??phenoxazin??3??one—questiomycin A, its derivative 2b, and cinnabarinic acid and actinocin (2c, d). Substrates with methyl groups at 4 and 5 positions of benzene ring were ...