Abstract
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 triacetyl-cellulose and the subsequent configurational correlation with a binaphthol derivative of known absolute configuration is reported.
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