Electrophilic addition of a cyano group to nitrogen, giving an N-cyano ammonium salt in a reaction that is immeasurably fast even at -60ยฐC.
- Attack by the bromide ion on a carbon atom attached to nitrogen, giving a cyanamide and RBr in a reaction whose rate is measurable between -30 and -9ยฐC.
NMR measurements on l-cyano-trans-decahydro-l-methylquinolinium bromide show the second stage to be a reaction of the first order; it occurs ten times faster in CDC1, than in CD,CN. The activation energy of decomposition amounts to 18 kcal/mol. On replacement of the bromide by a less nucleophilic (or non-nucleophilic) anion, e. g., hexachloroantimonate, methanesulfonate, p-toluenesulfonate, or tetrafluoroborate, stable quaternary N-cyano ammonium salts can be isolated for the first time, analyzed, and subjected to examination of their chemical behavior.
Recently also we have been able to trap the adduct formed from methyl chloroformate and trans-decahydro-l-methylquinoline at low temperature and to stabilize it as fluoroborate.
To determine the stereochemistry of the N-isomeric products obtained we have separated them as fluoroborates and are presently studying (a) their nuclear Overhauser effect at 250 MHz and at 100 MHz, (b) their l3C-NMR spectra, and (c) the structure of the major product by X-ray methods.