Rapid Heteronuclear Single Quantum Correlation NMR Spectra at Natural Abundance

A novel NMR experiment, the so-called ASAP-HSQC, is introduced that allows the detection of heteronuclear one-bond correlations in less than 30 s on small molecules at natural abundance without compromises in sweep width, resolution or spectral quality. Equally, the experiment allows a significant increase in digital resolution or a moderate senstitivity enhancement in the same overall experiment time compared to a conventional HSQC. The gain is a consequence of keeping all unused proton magnetization along z during acquisition, so that the previously reported ASAP and ALSOFAST approaches can be transferred from HMQC to HSQC-type experiments. Next to basic and broadband pulse sequences, a characterization of the sequence with respect to minimum measurement time, sensitivity gain, and advantages in resolution compared to state-of-the-art experiments is given.