13C NMR spectral studies of arecoline,hordenine, strychnine and brucine

The ¹³C n.m.r. spectra of arecoline, hordenine, strychnine, brucine and their salts were determined and the chemical shifts reported previously for arecoline have been verified by single frequency proton decoupling techniques. Effects of protonation on the carbon resonances in aiding unambiguous assignments in strychnine and brucine are discussed. The quaternary N-methiodide of brucine was also studied to confirm the assignments made for carbon atoms adjacent to the basic N atom.