F···HO as the main transmission mechanism for 1hJF,H(O) coupling constant in 2'-fluoroflavonol

Abstract

Flavonoids are useful compounds in medicinal chemistry and exhibit conformational isomerism, which is ruled by intramolecular interactions. One of the main intramolecular forces governing the stability of conformations is the hydrogen bond. Hydrogen bond involving fluorine covalently bonded to carbon has been found to be rare, but it appears in 2′‐fluoroflavonol, although the F···HO hydrogen bond cannot be considered the main effect governing the conformational stability of this compound. Because 19F is magnetically active and suitable for NMR studies, the 1hJF,H(O) coupling constant can be used as a probe for such an interaction in 2′‐fluoroflavonol. In fact, the 1hJF,H(O) coupling was computationally analyzed in this work, and the F···HO hydrogen bond was found to be its main transmission mechanism, which modulates this coupling in 2′‐fluoroflavonol, rather than overlap of proximate electronic clouds, such as in 2‐fluorophenol.