Nitrogen characterization, weak base

Table III shows that 63.4% of the nitrogen in the very weak base concentrate is N-H nitrogen. Of this 63.4% of the nitrogen, 29% has already been characterized as being in pyrroles and indoles without N-substitution. This leaves 34.4% of the nitrogen to be in carbazoles without N-substitution. Table IV shows that 71% of the nitrogen is in carbazole type compounds, and if 34.4% has no N-substitution then 36.6% has N-substitution. Table V is a summary of these findings. Thus...

Two aspidofractinine-type compounds, lahadinines A (233) and B (234), obtained from Kopsia pauciflora are remarkable for having a cyano-substituent at C(21) [162]. The mass-spectra of these alkaloids are characterized by a strong molecular ion (usually also the base peak), with the odd mass indicating the presence of a third nitrogen. Fragments attributable to loss of CN and HCN were also detected in the mass-spectrum and the IR spectrum showed a weak band at ca. 2250 cm. The characteristic H(21) signal was absent in the H NMR... 

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