Benzene-induced shifts (BIS) in the 1H NMR spectra of nine chromeno-compounds have been studied. It provides a simple non-destructive technique for distinguishing linear isomers of chromenoflavones from there angular counterpart. BIS also assists in the assignment of chromene proton signals in chromeno-compounds.
A. Banerji and Luthria, D. L., “Benzene induced 1H NMR shifts of chromeno-compounds: an aid to differentiate linear and angular chromenoflavones”, Spectroscopy letters, vol. 23, pp. 1–12, 1990.