A comparative study of NMR chemical shifts of sparteine thiolactams and lactams

The 13C and 1H NMR spectra of the four possible thiolactams of sparteine () were recorded and the thiolactam group effects were determined. Most of the effects are greater than those of the lactam group in the oxo analogs. A good linear correlation between the 13C chemical shifts of CS and those of CO was found. The effects could help in assignment of the spectra and determination of conformation of thiolactams and related thiocarbonyl compounds.