One-pot synthesis of dibenzofuran-1,4-diones

One-pot synthesis of dibenzofuran-1,4-diones 8 from 4-methoxyphenols (or 4-methoxy-l-naphthols) 4 was achieved by oxidative dimerization over a semiconductor in heated, O 2 -saturated toluene, followed by selective monodemethylation, and oxidative cyclization.