A Facile Synthesis of 2-Amino-2′-hydroxy-1,1′-binaphthyl and 2,2′-Diamino-1,1′-binaphthyl by Oxidative Coupling Using Copper(II) Chloride

Oxidative coupling of a 1:1 mixture of 2-naphthol (1) and 2-naphthylamine (2) by means of copper(II) chloride in the presence of benzylamine gives the cross-coupled product 3 (2-amino-2′-hydroxy-1,1′-binaphthyl) in 68% yield while copper(II) chloride itself yields mainly the homo-coupled diamine 4 (2,2′-diamino-1,1′-binaphthyl) in 33% yield. Pure 4 was prepared by oxidation of 2-naphthylamine (2) using (PhCH2NH2)4CUCl2 in 58% yield.