Copper-catalysed oxidative alkoxylation of acyl- and carbomethoxy-hydroquinones

Oxidation of title hydroquinones by an [O2/CuICl] system in the presence of alcohols yields (71–88%) corresponding regioselectively 3-alkoxylated compounds. Compared with the classical procedure (silver oxide oxidation) in which alcohols have to be added to intermediate quinones in a second step, leading to a 1:1 mixture of starting material and final quinones, this new selective one-pot system does not oxidize alcohols and regenerates intermediate quinones from starting hydroquinones. Moreover, in situ trapping of the unstable formyl-quinone now allows the preparation of its 3-alkoxy derivative.