Economizing spectrometer time and broadband excitation in small-molecule heteronuclear NMR correlation spectroscopy. Broadband HMBC

Two new schemes for heteronuclear broadband NMR long-range correlation are presented. One scheme employs the conventional low-pass J filter HMBC pulse sequence and combines spectra recorded with different excitation delays in order to achieve broadband excitation over a range of long-range coupling constants. The other scheme is an extension that includes a ‘non-destructive’ low-pass J filter allowing a one-bond correlation spectrum to be extracted from the same data set optimized for HMBC. Hence the time to record a separate HSQC spectrum is saved.