Substituent Effect on Regioselectivity in Oxygenation of Multisubstituted Acenes

Reaction of substituted acenes such as anthracene, naphthacene, and pentacene derivatives with O2 was dependent on the substituents and their positions. The orientation is in contrast to Diels–Alder reaction with DDQ in the case of naphthacene and pentacene derivatives. 1,2,3,4,5,6,7,8-Octamethylanthracene reacted with O2 to afford a doubly oxygenated compound (diendoperoxide) at both end rings.