Heteroaromatic quaternary ammonium salts

Substance classes Properties — Effectiveness — Applications 16.1.8 Heteroaromatic quaternary ammonium salts — other examples Alkyl-isoquinolinium bromide (alkyl = C12H25)... 

This review deals with the formation of reduced pyridines and their benzo analogs from the parent heteroaromatic bases. Included are acridines, isoquinolines, pyridines and quinolines and their quaternary ammonium salts and N-oxides. The formation of the reduced species by other methods, e.g. Hantzsch dihydropyridine synthesis, is not addressed. 

The classical structures of pyrrole, furan and thiophene (31) suggest that these compounds might show chemical reactions similar to those of amines, ethers and thioethers (32) respectively. On this basis, the initial attack of the electrophile would be expected to take place at the heteroatom and lead to products such as quaternary ammonium and oxonium salts, sulfoxides and sulfones. Products of this type from the heteroaromatic compounds under consideration are relatively rare. 

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