Assignment of the carbon-13 spectrum of vancomycin and its derivatives

The antibiotic vancomycin and its derivatives CDP-I and aglucovancomycin have been studied by 13C n.m.r. spectroscopy. The spectra have been partially assigned by means of model compounds, pH titrations, addition of lanthanide ions, selective {1H} decoupling, and 13C labelling experiments, allowing all but four of the 66 carbon atoms in vancomycin to be assigned. Full details of the assignment are presented.