Among different bidentate bipyridine ligands (Table 1, entries
1e4), neocuproine completes the oxidation reaction in an hour in
the presence of CuCl2.2H2O and water with high yield (Table 1,
entry 1). Reactions in the absence of CuCl2 (entry 5) and/or ligand
(entry 6) affording comparable product yields with that of only
TBHP (entry 7) suggest that TBHP is responsible for the conversion.