Region-selective inverse-detected long-range heteronuclear chemical shift correlation using shaped pulses

F1 region‐selected variants of the HMBC experiment were compared and evaluated. In particular, a significant advantage was demonstrated for an E‐BURP‐2 pulse over a Gaussian 270° pulse for region‐selected applications. The Gaussian 270° pulse would still, however, be the preferred pulse for use in single‐resonance, on‐resonance selective excitation. Data are presented from NMR spectrometers both equipped and not equipped with programmable pulse modulators (waveform generators). Pulse evaluations were performed using the simple heteroaromatic alkaloid quindoline; application of the technique to the important immunosuppressive cyclic peptide cyclosporin‐A is also presented and discussed.