Conformational analysis of the dibenzo [a,g]-quinolizidines by spectroscopic means. II—The use of high resolution 270 MHz proton magnetic resonance

The 270 MHz ¹H n.m.r. spectra of some model tetrahydroprotoberberines have been analysed and the dependence of the chemical shifts and the geminal and interbenzylic coupling constants on the conformation examined. Their use for conformational analysis was illustrated on two 8-methyl substituted epimers.