Lanthanide shifts in the ¹H N.M.R. spectra of peri-Alkoxy- and -Alkylamino-quinones

Abstract

Unusually large lanthanide-induced shifts are observed for proton resonances of methoxy, ethoxy and dimethylamino substituents peri to carbonyl groups of anthraquinones and naphthoquinones. Such an arrangement allows the substrate to act as a bidentate ligand and is evidently the favoured site of coordination.