STRUCTURAL ELUCIDATION OF GERMINE ESTERS ISOLATED FROM VERATRUM-NIGRUM L TOTAL ASSIGNMENT OF H-1 AND C-13 NUCLEAR MAGNETIC RESONANCES BY 2-DIMENSIONAL NMR TECHNIQUES

The application of two-dimensional phase-sensitive COSY, ROESY and C-13-H-1 shift correlation spectroscopy in the structural elucidation and stereochemical assignment of the steroidal alkaloids 15-(2-methylbutyryl)germine, 3-(2-hydroxy-2-methylbutyryl)-15-(2-methylbutyryl)germine and 16-(2-methylbutyryl)germine is reported. It is shown that two-dimensional C-13-H-1 heteronuclear long-range correlation spectroscopy is an invaluable method for the stereochemical assignment of proton resonances which overlap in H-1 NMR and homonuclear correlation spectra.