Carbon–hydrogen and carbon–carbon coupling patterns in the cephalosporin series

Abstract

The ¹³C NMR spectra of the skeleton of 7-amino-3-cephem-4-carboxylic acid derivatives and the 2-(2-aminothiazol-4-yl)-2-alkoxyiminoacetyl substituent were analysed searching for the rules which might be helpful in the structure determination of new cephalosporin antibiotics and their isomers. The ¹³C NMR decoupled spectra were fully interpreted on the basis of ¹³C–¹H and ¹³C–¹³C coupling patterns. The method for unambiguous assignment of the Z/E geometry of 2-(2-aminothiazol-4-yl)-2-alkoxyiminoacetyl groups was established.