The oxidative cross-coupling of substituted 2-naphthols. Part I: The scope and limitations

Article abstract of DOI:10.1016/S0040-4020(01)88318-6

Highly selective oxidative cross-coupling of differently substituted 2-naphthols mediated by Cu(II)-tert-butyl amine complexes is described. The 'cross'-products are obtained in good to excellent yields and the selectivity up to >90% is observed depending on the substitution of naphthol nuclei. The alternative procedures - the cross-coupling of free naphthols with CuCl(OMe) as well as the coupling of sodium naphtholates with anhydrous copper(II) chloride - were also studied. All these methods enable a simple and high-yield access to the unsymmetrically substituted binaphthols. A successful optical resolution of methyl 2,2'-dihydroxy-1,1'-binaphthalene-3-carboxylate by means of liquid chromatography on triacetylcellulose and the subsequent configurational correlation with a binaphthol derivative of known absolute configuration is reported.