A novel and facile method of introducing 4-hydroxyl group into the aromatic ring of azabenzanthrone compounds was carried out by reacting azabenzanthrone compounds with hydrazine hydrate or hydroxylamine hydrochloride and sodium hydroxide in diethylene glycol （DEG） solvent. The mechanism of reaction may involve an amino intermediate and follow a hydroxyl substitution process.
Fang Xian Ning Xiang Weng Shi Liang Huang Li Jun Gu Zhi Shu Huang Lian Quan Gu
