At room temperature, both I1 and I4 feature two dominant conformers that interconvert (Figure ). The relative population of the conformers can be directly deduced from the J-coupling constant of the α-protons of the methoxy-group (denoted H α in the following). The NMR signal of H α is a multiplet resulting from two distinct vicinal proton-proton J-couplings (J A-B , J A-C ). Both J A-B and J A-C are rotational averages over all conformers. Here, we extracted the total scalar coupling J tot = J A-B + J A-C as the frequency difference between the two outermost peaks of the multiple. In chloroform, the predominant population of the gauche conformer minimizes J tot (Figure ), while a higher value is observed in DMSO from an enhanced population of the trans conformer (Figure ).