Through-space transmission of 19F-13C coupling via an intermediate bond. An experimental and theoretical study

Abstract

In order to obtain a deeper insight into the title effect, several compounds with an F atom very close to a C-H of a nearby functional group were synthesized and the relevant couplings measured. The most conspicuous case was that of 8-fluoro-2-hydroxynaphthalene-l-carbaldehyde where a close proximity between the F and H atoms is the result of fluorine-oxygen repulsion and the formation of an intramolecular hydrogen bond between the hydroxyl and carbonyl groups. The experimental four-bond J(F, CHO) coupling is 26·2 Hz. A compound very similar to this one, but without the OH group, was chosen on which to perform a polarization propagator analysis of the through-space (ts) coupling pathways, at..