The NMR spectra of fluoroaromatics—IV:1H and 19F spectra of some fluorinated benzofurans

Abstract
The complete analyses of the 19F spectra of some fluorinated benzofurans are given. These provide an unambiguous determination of the substituent position in these compounds. Comparison of the 19F SCS and coupling constants in the benzofuran, benzothiophene and benzene series shows that 19F spectral parameters can be transposed from the benzene series with caution.A large increase in the para FF coupling with ring closure of the hetero‐ring is noteworthy. A long‐range through‐space 8JH is reported which arises from the proximity of the 3 carboethoxy methyl group and the C4 fluorine in these molecules.