Accurate knowledge of NMR coupling constants is of prime importance for molecular structure analysis. Vicinal scalar couplings deliver direct information on dihedral angles between protons and are thus sensitive to molecular configuration and conformation. For natural product structure elucidation, all scalar couplings can be confronted with density functional theory calculations to validate a structure proposal. 2 Also residual dipolar couplings (RDCs) provide a valuable supplement for configurational analysis. Homonuclear 1 H-1 H couplings are particularly valuable in this respect given their abundance in organic molecules and the sensitivity of 1 H NMR, but this abundance also hampers their quantification. Individual 1 H-1 H couplings are often not straightforward to extract from complex multiplets, especially if they overlap. Stefan Berger proposed an elegant solution to this problem with the SERF experiment, in which frequency-selective pulses are combined with a 2D J-resolved (2DJ) experiment in such a way that only couplings to a chosen proton appear along the indirect dimension. Many further improvements have been proposed, 5 including the simultaneous observation of the full spectral bandwidth by employing the Zangger-Sterk 6 or PSYCHE elements, yielding the G-SERF and PSYCHEDELIC experiments, respectively. 8 Selective 2DJ experiments are closely related to pure shift NMR, 5b,9 and both are easily combined to homodecouple the chemical shift dimension, greatly improving spectral resolution. This has allowed extraction of individual couplings even for complex molecules or mixtures featuring very crowded 1 H NMR spectra. Despite these advances, all current selective 2DJ methods suffer from one major and fundamental limitation. When two coupled protons have close chemical shifts, meaning their difference in resonance frequencies approaches the value of the coupling, the first order approximation of the nuclear spin Hamiltonian is no longer valid. This situation is referred to as strong coupling, and affects the multiplet structures in a complex way. This includes perturbations in both line intensities (cf. the well-known roof-effect) and line positions within the multiplet. For a simple ABX spin system, where A and B are the strongly coupled protons and X a proton weakly coupled to both A and B, theoretical analyses reveal that the line splittings associated with JAX and JBX are no longer exactly equal to those couplings. 12 This thus affects the accuracy of the coupling measurement. In principle this could be compensated for with spin-simulations, but in practice this is complicated for more complex spin systems and requires knowledge of all chemicals shifts and J-couplings involved. Within 2DJ spectroscopy and pure shift NMR spectra, strong coupling also leads to unwanted additional responses, commonly referred to as strong coupling 'artifacts' (even though these are not caused by an instrumental imperfection, but an inherent response from the spin system on the experiment). For selective 2DJ spectroscopy, an additional complication arises. When strongly coupled protons are nearly or fully chemical shift degenerate, their multiplets typically will overlap and the individual lines within them cannot be 'purely' associated with one proton. The spin-states of these protons thus cannot be independently inverted using a frequency-selective pulse, and the coupling between them is inaccessible with current selective 2DJ methods.