Synthesis of C2-Symmetrical Diamine Based on (1R)-(+)-Camphor and Application to Oxidative Aryl Coupling of Naphthols

The new C2-symmetrical 1,2-diamine {N,N′-bis[(1R,2R,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl]-1,2-ethanediamine}3 has been synthesized from commercial (1R)-(+)-camphor 1 and scrutinized as ligand in the oxidative biaryl coupling of naphthol derivatives. Under the optimal conditions employing a Cu(I)-3 triflate complex (10 mol%) in dichloroethane–MeCN and molecular sieves with air as the oxidant, aryl coupling of naphthol derivatives could be achieved in satisfactory yields (48–90% yield) and ees of up to 65%. The ester moiety at the 3-position of the substrate was found to be crucial for a satisfactory asymmetric induction in the present coupling reaction.