No abstract

N‐Aryl‐mono‐, ‐tri‐ and ‐pentacyclic pyridinium cations react with S‐ and C‐nucleophiles to give: (i) simple addition of hydride at the α‐ring position, (ii) nucleophilic addition of thiophenoxide at the γ‐ring position, (iii) deprotonation at the 6‐position of a 5,6‐dihydroquinolinium ring followed by prototropic shift to give a 1,2‐dihydroquinoline derivative, (iv) ring contraction of a pyridine to a pyrrole ring, and (v) nucleophilic displacement of the N‐aryl group.

Mono-, tri-, and penta-cyclic Nbenzylpyridinium tetrafluoroborates undergo thermolysis in chlorobenzene as solvent to give products of benzylation both of the solvent and of the pyridine leaving group. Thermolysis alone, and in nitrobenzene as solvent, yielded mainly products of benzylation of the leaving group. The results support the previously postulated mechanism of unimolecular solvolysis of compounds of these types in non-polar solvents.