Studies on quinones. Part 40: Synthesis and cytotoxicity evaluation of anthraquinone epoxides and isomerization products

Abstract

Aerobic oxidation of 1,4,4a,10a-tetrahydro-1,4-alkano-5,10-anthraquinones and thiophene-analogues in dichloromethane–DBU yielded the corresponding dihydroalkanoquinones which, depending on their structures, react with in situ generated hydroperoxide anion to give quinone epoxides and/or hydroperoxides. The calcium hydroxide-induced rearrangement of quinone epoxides yielded furan-containing angular quinones. The cytotoxic activities of quinone epoxides and their isomerization products were evaluated in vitro against normal human lung fibroblasts (MRC-5) and human cancer gastric epithelial cells (AGS). Aerobic oxidation of Diels–Alder adducts of naphthoquinones and thiophene-analogues in dichloromethane–DBU provides access to quinone epoxides.