COMPUTER-ASSISTED SHIFT-REAGENT PMR STUDY OF METHOXYFLAVONES

The complete assignment of the proton chemical shifts of all possible monomethooxyflavones was achieved by comparison of individual spectra with those of A- and B-ring polydeuterioflavone and from shift reagent experiments performed in the presence of Pr(fod)3. The lanthanide induced shifts obtained by least-square adjustment were used as input data to localize the metal atom during interaction with the flavones, assuming a pseudocontact behavior. The results show that in most cases the lanthanide atom interacts exclusively with the flavone carbonyl, although both 3- and 5-methoxyflavone behave as bidenate ligands. © 1979.