Application of a lanthanide shift reagent, Eu(fod)3 to the elucidation of the structures of flavones and related compounds

Abstract

Application of the paramagnetic shift reagent Eu(fod)₃ in n.m.r. spectral studies of 5,7-dimethoxyflavone derivatives showed that the signals due to H-3, H-6, and H-8 could be distinguished on the basis of lanthanide-induced shifts; the method is thus useful for structural assignments and has been successfully applied to methyl ethers of biflavones, isoflavones, and xanthones. The difference in co-ordination state between Eu(fod)₃ and Eu(dpm)₃ in the case of 5-methoxychromone derivatives is discussed.