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

Oxidation of title hydroquinones by an [O-2/(CuCl)-Cl-I] system in the pres ence of alcohols yields (71-88%) corresponding regioselectively 3-alkoxylat ed compounds. Compared with the classical procedure (silver oxide oxidation ) in which alcohols have to be added to intermediate quinones in a second s tep, leading to a 1:1 mixture of starting material and final quinones, this new selective one-pot system does not oxidize alcohols and regenerates int ermediate quinones from starting hydroquinones. Moreover, in situ trapping of the unstable formyl-quinone now allows the preparation of its 3-alkoxy d erivative. (C) 2000 Elsevier Science Ltd. All rights reserved.