Aerobic oxidative dimerization of 1-naphthols to 2,2′-binaphthoquinones mediated by SnCl4 and its application to natural product synthesis

We developed a simple method for the direct synthesis of 2,2′-binaphthoquinones, utilizing oxidative dimerization via electron donor–acceptor complex formation of 1-naphthols with SnCl4 in the presence of dioxygen. This oxidation involves a catalytic cycle of SnCl4, and the reaction mechanism is discussed. As an application of this method to natural products synthesis, we describe facile biomimetic syntheses of the binaphthoquinones 3,3′-bijuglone, 3,3′-biplumbagin and elliptinone.