Stereochemical analysis and complete 1H/13C NMR chemical shift assignments of matrine. Application of NOE and two‐dimensional NMR techniques

The stereochemical and structural analysis of matrine was carried out using nuclear magnetic resonance spectroscopy. Several methods, including 13C1H two‐dimensional shift correlation spectroscopy, 1H1H two‐dimensional correlated spectroscopy and measurements of vicinal 1H1H coupling constants were used for chemical shift assignments and configurational analysis. Nuclear Overhauser effect difference spectroscopy was used to establish the sterochemistry. This investigation demonstrates the power of two‐dimensional NMR techniques and the nuclear Overhauser effect (NOE) in the structural determination of natural products.