Semiconductor-mediated oxidative dimerization of 1-naphthols with dioxygen and O-demethylation of the enol-ethers by SnO2 without dioxygen

Oxidative dimerization of 1-naphthols with dioxygen in the presence of a semiconductor, such as SnO2, ZrO2, or activated charcoal, as a catalytic mediator takes place selectively to give the corresponding 2,2′-binaphthols or 2,2′-binaphthyl-1,1′-quinones in excellent yields without light irradiation. The catalytic activity of SnO2 could be fully restored by appropriate reactivation treatment after the oxidation. In addition, SnO2 without dioxygen catalyzes selective O-demethylation of the enol-ethers to .