Carbon Multiplicity Editing in Long-Range Heteronuclear Correlation NMR Experiments: A Valuable Tool for the Structure Elucidation of Natural Products

A recently developed NMR method to simultaneously obtain both long-range heteronuclear correlations and carbon multiplicity information in a single experiment, ME-selHSQMBC, is demonstrated as a potentially useful technique for chemical shift assignment and structure elucidation of natural products presenting complicated NMR spectra. Carbon multiplicities, even for C/CH2 and odd for CH/CH3 resonances, can be distinguished directly from the relative positive/negative phase of cross-peaks. In addition, connectivity networks can be further extended by incorporating a TOCSY propagation step. Staurosporine (1) and sungucine (2) are utilized as model compounds to demonstrate these techniques.